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FUSE demonstrator document

FUSE Application Experiment EPC1 24571.

Monitoring TTN: IAM F&E GmbH, Braunschweig, Germany

BABY MONITORING SYSTEM VitaGuard® VG3000Mixed-signal ASIC with pay-back period of one year

Abstract

GeTeMed GmbH (Gesellschaft für Technische Medizin mbH) was founded in 1984, issituated in Teltow (South of Berlin) and manufactures, markets and sells medical equipmentin two main areas: baby monitoring and ECG analysis. The baby monitoring systems monitorboth the heart rate and respiration of infants to combat the sudden infant death syndrome(SIDS). These monitors are intended for both home and clinical use. The ECG analysissystems include Holter monitoring (24h ECG analysis), rest and stress ECG analysis.

GeTeMed took part in the FUSE programme to develop an ASIC for use in its main babymonitoring product VitaGuard®. This system uses three electrodes to detect and analysis therespiration and ECG signals. When an apnea occurs or when the heart rate falls below orexceeds preset limits, an alarm is generated to warn the childminders. The system alsostores the incoming ECG and respiration signals prior, during and after the alarm episodes,so as to give the handling physician the possibility to determine the cause of the alarms andmake appropriate decisions. The main objectives for developing an ASIC for this systemwere to reduce size and manufacturing costs, increase reliability by reducing the number ofcomponents and inhibit the system from being easily copied. As the present system containsa large number of discrete digital and analogue SMT components, the aim was to integrateas many of these components as possible and bring the whole system onto one small PCB.

To achieve this aim, the FUSE project was started in September 1997. It was decided todesign a mixed signal ASIC, as this was the only feasible means of reducing the number ofboth analogue and digital components. CMOS technology was selected so as to keep thepower consumption of the final product within reasonable levels. The project cost 100kECU,took nineteen months to complete and finished at the end of March 1999. It was clear fromthe start that such an enormous task could not be carried out by GeTeMed alone, asGeTeMed had little previous experience in ASIC design and none of the complex andexpensive software tools needed to successfully complete such a task. It was thereforedecided to carry out the project with an ASIC design center. The choice fell to MAZ-Brandenburg for a number of reasons – they had vast experience, all the necessary tools,good contacts to silicon foundries and were ideally located not far from GeTeMed. Theanalogue section of the final ASIC accounts for approx. 25% of the chip area. The digitalcomponents make up the rest of the chip area as follows: digital filter 50%, SRAM 15% andthe remaining glue logic 10%.

The FUSE project has benefited GeTeMed to a great extent in that it has given an insightand understanding of the mechanisms behind ASIC designs, the costs involved and thebenefits to be reaped by participating in such undertakings. The final cost analysis andreturn of investment cannot be calculated at the moment since the end product incorporatingthe ASIC has not gone on the market yet. From experience, the task of designing the new

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system (both hardware and software) along with the extensive verification and validationprocedures necessary to comply with the Medical Device Directive regulations take aboutone year in total. Bearing in mind the projected savings per unit, however, the investmentshould be recuperated by selling 400 units within a period of six to twelve months. Theproject thus has a pay-back period of one year. With an overall lifetime of at least five yearsa return on investment of over 500% can be expected. The main lesson learned was thatsuch a project can only be successful by working with reliable and experienced partners.

KeywordsMedical equipment, mixed-signal ASIC, measurement system, ECG, ECG analysis, SIDS,digital filter, band pass filter, VHDL simulation

FUSE Signature5 0 131 105 0 350 2 3310 1 33 D

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1. Company name and address

GeTeMed GmbHOderstr. 5914513 Teltow

Coordinator of the experiment: Robert DownesTel.: +49 (0)3328 3942 0Fax.: +49 (0)3328 3942 99

2. Company size

The total number of employees is 21, with 6 involved in the electronic development. Ofthese, 4 are involved in hardware design and two in software design. The company turnoverfor the last two years was as follows:

1996: 1.8 million euro1997: 2.1 million eiro

The expected turnover for 1998 is around 2.5 million euro.

3. Company business description

GeTeMed designs, manufactures, markets and sells medical equipment in two main areas.One area consists of monitoring systems that monitor both the heart rate and respiration ofinfants in order to combat the sudden infant death syndrome (SIDS). These monitors areintended for both home and clinical use. The other area is centered around ECG analysissystems consisting of Holter monitoring (24h ECG analysis), rest and stress ECG analysis.The companies products are:

BabyGuard® BS1000 Apnea monitorVitaGuard® VG2000 System to monitor both heart rate and respiration of infantsVitaGuard® VG3000 System to monitor heart rate, respiration and SpO2 of infantsCardioDay® CD1000 24-hour Holter analysis systemCardioLink® CL1000 12-channel rest ECG system

4. Company markets and competitive position at the start of the AE

The company sells its baby monitoring products in Germany, Austria and Switzerlandthrough a network of agents. The monitors are used mainly for home monitoring. The ECGanalysis systems (CardioDay® and CardioLink®) are sold both in clinics and privatecardiological practices throughout Germany, Holland, Switzerland and France.

Up to the introduction of the VitaGuard® monitor in 1993, the market in Germany had beenmainly supplied by high-priced products (between 3000 euro and 4500 euro) from USA(Corometrics, Edentec, Nellcor, Healthdyne), Great Britain (Graseby) and France (Kontron).All of these products are bulky and require a mains-supply power source. GeTeMeddeliberately set out to design a system that is compact, battery operated (and thereforeeasily transportable), attractively priced and, at the same time, offers a wider range offunctions, so that the end user can easily operate the system. GeTeMed’s position within theGerman market has steadily increased since the introduction of the VitaGuard® monitor. This

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increase has not gone unnoticed by its competitors so that over the last few years thecompetitors have dropped their prices dramatically. While this has livened the marketconsiderably and brought obvious advantages to the customers, it has meant that GeTeMedhas needed to decrease production costs in order to keep ahead of its competitors.GeTeMed also needs to shorten production and test times so as to satisfy the increaseddemand for its products. The best way to meet this goal is by integrating the system circuitryon a large scale, thus reducing the number of system components.

The VitaGuard® turnover for 1995 was 0.85 million euro and increased to 1.3 million euro in1996. Over the last years GeTeMed has steadily built up an agent network so that there arenow agents that cover practically all parts of Germany. These agents demonstrate thesystems to the doctors and nurses, deliver the monitors to the hospitals, teach the parentshow to use the monitor and offer 24 hour customer service when parents are havingdifficulties. Although GeTeMed now also has agents in Austria and Switzerland, the nextstep is to expand into the rest of Europe. However, before this task can begin in earnest, thepresent costs need to be substantially reduced. One reason is the fact that the costsincrease with distance e.g. transport costs and costs associated with meeting agents on aregular basis. Another reason is that it is uncertain as to whether the present prices can bemaintained in the future, especially in some of the Eastern countries.

GeTeMed is currently market leader in the area of baby monitoring (home monitoring of bothrespiration and heart rate) and has a market share of around 40%. The market share in thehighly competitive Holter recording market has increased steadily since GeTeMed startedwith this product line in 1993 and currently has around 17% of the high-end market inGermany. The rest and stress ECG systems are new so that no reliable market figures areavailable. The whole area of ECG monitoring is becoming increasingly competitive with alarge number of cheaply priced products aimed at private practitioners. GeTeMed hasavoided getting involved in this area as the price dumping strategy of many manufacturersinvariably leads to low-quality systems being produced. GeTeMed aims to remain in thehigh-end league and provide good quality analysis hardware and software.

5. Product to be improved and its industrial sector

The existing product to be improved is called the VitaGuard® Monitor. The first monitor ofthis type was developed in 1993. The monitor was designed to monitor both the respirationand heart rate activities of infants as a means of combating the sudden infant deathsyndrome (SIDS), commonlyknown as cot deaths. Thisphenomenon has thecharacteristic that the infantceases to breathe and goes intoa state of complete immobilitycalled apnea. In Germany alone,around 2000 such deaths areregistered each year. The figuresfor other industrialised countriesare similar. The danger prevailsin the first two years and is mostcommonly observed between thesecond and fourth month afterbirth. Although a certain riskfactor can be established for achild, for example, due topremature birth, respiration or heart problems, previous family history, etc., the actual cause

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is still unknown. Thus, one way of preventing such deaths is to monitor the child’s respirationand heart rate in both the clinic and at home. The electronic components of the first monitorwere through-hole components spread over two printed circuit boards as shown:

The method used by the VitaGuard® to monitor the respiration is called the impedancemethod. This method results from the fact that most doctors agree that, if the child needs tobe monitored in the first place, then the heart rate should also be monitored. Since at least 3electrodes are needed to monitor the heart reliably, these electrodes should also be used tomonitor the respiration so as not to cause any further inconvenience to the child or theparents. The respiration signal is obtained by measuring the transthoracic impedancechanges due to respiration. The main problem, however, is that the heart is also locatedbetween these two electrodes and each heart beat also causes an impedance changesimilar to the change due to respiration. Children’s heart rates can vary between 40 and 300beats per minute (abnormal extremes) while respiration rates vary between 40 and 140breaths per minute. Since the frequency ranges of both signal sources overlap, conventionalfiltering techniques fail to reliably distinguish between the two signals.

The danger lies in the fact that when the child ceases to breathe at first, the heart continuesto beat. A system that mistakenly registers the heart signal as respiration will fail to give analarm in time. Such a system will alarm when the heart also ceases to beat which is then toolate. Thus, an intelligent microprocessor based algorithm combined with innovative filteringtechniques is needed to reliably extract the respiration information and give an alarm whenthe breathing stops. The first monitor developed had two displays, one for the respirationsection and one for the heart rate section. This monitor was further developed in 1995 toincrease functional flexibility i.e. make it possible to display numbers and incorporate a menustructure.

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The user interface consists of a set of six buttons and an alpha-numerical LCD display. TheLCD normally displaysthe respiration patternand the actual heartrate along with theupper and lower heartrate limits and therespiration pausesetting. A user-friendly,intuitive menu structureenables quick accessto all systemparameters and allowsfirst users toconfidently operate thesystem within a veryshort period. Thetechnology used in thismonitor was mostlySMT, which meant thatthe number of printedcircuit boards could bereduced to one.

When an alarm situation occurs, the system reacts by producing both an acoustic and avisual alarm signal. The analysis of alarm episodes has shown that the acoustic signal aloneis often sufficient to reanimate the infant. Other alarm types also exist (periodic respirationand user defined silent alarms), but these are mainly used for research purposes and are notgenerally activated in the home monitoring situation. There are basically three types ofalarm:

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Alarm type Typical settings CauseApnea alarm 20 seconds Respiration ceases for a period longer than

the pause setting.Bradycardia alarm 90 bpm Heart rate falls below the bradycardia limitTachycardia alarm 190 bpm Heart rate rises above the tachycardia limit

Some of the features unique to this system include the possibility of selecting the ECG leadconfiguration, battery lifetime of around 1 month, the integrated basal impedance and QRS-peak measurement functions as well as the possibility of storing alarm episodes (includingECG) as a function of time, a feature which no other European monitor offered at the time ofdevelopment.

The main aims in the area of baby monitoring are twofold. The first aim is to reduce the sizeand manufacturing costs of the VitaGuard® monitor through the implementation of the ASICdesigned throughout this AE. This will enhance GeTeMed’s position within the homemonitoring market. The second aim is to enter the area of clinical monitoring. This will beachieved by incorporating modules for measuring temperature, oxygen saturation and bloodpressure into the present VitaGuard® system, thus increasing the number of physiologicalparameters measured to five. In the area of cardiology, GeTeMed is currently in the processof improving their Holter, rest and stress ECG systems by uniting them under a Windows95/NT user interface with data transfer possibilities to standard patient handling software.The aim is to offer complete systems to suit all the cardiologists needs, ranging from theprivate practice to university clinics.

One further aim of gearing towards ASIC technology for future developments is to reducethe possibility of the product being copied by other manufacturers, a problem that isbecoming more and more evident throughout the world. The following block diagram gives abrief overview of the internal components of the system to be improved:

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6. Description of the technical product improvements

As VitaGuard® is a very complex system, both in terms of hardware and software, the finalimproved product is not available at the moment. Exact figures or information aboutmanufacturing cost reductions, test cost reductions, process yield improvements, productperformance improvements usability improvements and so on are therefore not available.However, the high degree of miniaturisation due to the ASIC will bring about a notablereduction in costs. The following is a block diagram of the new system with ASIC:

The ASIC design can be split into two parts - an analogue section and a digital section. Therespiration signal fed to the microprocessor is corrupted due to movement and cardiogenicartefacts. In order to extract the respiration information, four analogue signals aresimultaneously processed by the microprocessor software algorithms. These four signals arepicked up using three electrodes, amplified, filtered and finally fed to a 10-bit analogue-to-digital converter.

Signal Bandwidth (Hz) Gain (dB) Sampling Rate (Hz)Respiration 0.1 – 3 80 16Artefact 2 – 6 80 16QRS 10 – 30 60 - 80 128ECG 0.1 – 40 60 128

The variable gain of the QRS signal is due to the automatic gain control circuitry. The fouramplifier/filter chains now integrated accounted for over one third of the available PCB spacein the present system. This demonstrates the importance of integrating a large proportion of

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the analogue circuitry. The circuitry, however, could not be integrated in its original form.This lies in the fact that the low-frequency, high-gain filter circuits require a large number ofhigh-valued resistors and capacitors. Thus, the analogue circuitry needed to be redesignedin such a way that it can be integrated into the ASIC. This task has been accomplished usingdigital filtering techniques. To increase the quality of the ECG signal stored, the new systemincludes a 10-bit analogue-to-digital converter instead of the 8-bit converter previouslyemployed. The following scheme was implemented to accommodate the four amplifiers andfiltering:

The four analogue signal are multiplexed at the input so that only one main amplifier isrequired. This is possible since the frequency components of the incoming biomedicalsignals are very low (max. 150Hz). The amplified signal is fed to an analogue-to-digitalconverter and the converted result is fed to the external microprocessor. To compensate forany amplifier offset voltage, an internal reference signal is also fed to the multiplexer. Acompensating offset (calibration voltage) is supplied from the digital-to-analogue converterand fed to the positive input of the operational amplifier, so that the output of the amplifier iszero, when the input is zero. Having converted the incoming signals, the filtering required foreach signal is carried out using the programmable digital filter. The advantages of the abovescheme are that only one analogue chain needed to be constructed, thus reducing therequired space within the ASIC. The analogue section accounts for approximately 25% ofthe total chip area.

The power supply inside the ASIC has been split. Power and ground for the analoguesection have separate inputs to those for the digital section. This was necessary in order toavoid interference spikes originating from the digital section having adverse effects on theanalogue section. With 5V operation, the noise level at the ADC inputs must be less than _LSB i.e. less than 1.22mV.

Digital circuitry integrated includes reset and interrupt logic for the microprocessor, addressdecoder circuitry for external devices (SRAM, Real Time Clock, etc.), and a 16-bit RRinterval counter for calculating the heart rate. Most of the digital glue logic in the presentsystem is realised using high-speed CMOS logic so that it could be easily transferred intothe ASIC domain. The ASIC also possess a number of general purpose input and latchedoutput ports for connecting other external devices such as LED’s, an LCD display, the alarmloudspeaker, a keyboard and so on. The glue logic takes up only a small section (about10%) of the total chip area. The digital filter logic and the associated SRAM for the filtercoefficients take up most of chip area. The filter logic itself accounts for half the chip spacewhile the SRAM takes up a further 15%. A sample controller has been implemented prior tothe digital filter. It selects the signal source to be sampled, sets the correct gain of theprogrammable gain amplifier, triggers the data conversion sequence and stores theconverted data in the appropriate register. The digital filter then processes the stored data.

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The sampling rate is 1000Hz and is derived from the master 16.384MHz clock. The 24-bitfilter coefficients are stored in the 768 byte internal SRAM and determine the filtercharacteristics. These coefficients are downloaded during system initialisation. Should theneed arise to modify the filter characteristic due to excessive movement for example, thennew coefficients can be downloaded at any time. The four filters are implemented as IIRfilters (Infinite Impulse Response) in parallel form.

A number of components could not be implemented for various reasons: the real-time clockalways needs a separate backup supply for when no external batteries are inserted as wellas a 32768Hz oscillator in order to keep the time; the EPROM with the system programmecould obviously not be integrated; large scale SRAM (1MB) could not be integrated due tosize and also because a backup supply is required to avoid loss of stored alarm episodes ifno external battery is present; the main power-supply (voltage regulators with electrolytecapacitors and inductors) could not be integrated; the input transformed for the respirationsignal, bypass capacitors and relays for obtaining the 3 ECG leads, etc. All thesecomponents remain external to the ASIC.

The technical data of the ASIC is as follows:Pins: 120 in total, 102 actually usedCasing: 120 pin CQFPSupply: 5V (analogue and digital separate)Chip area: 5,98mm x 4,42mm (≈26mm2) including pads

Clock: 16.384MHzTechnology: AMS CYE CMOS 0.8µm

Manufacturer: AMS

Digital filter Glue logic Gain stage Multiplexer

Bandgap

ADC

Channel 4

Channel 3

Channel 2

Channel 1

SRAM Resistors

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7. Choices and rationale for the selected technologies, tools and methodologies

The technological progression can basically be divided into the following steps:

- Printed circuit board (PCB)- Surface mounted technology (SMT)- Programmable gate arrays (FPGA)- Multi-chip module (MCM)- Gate array- Full-custom ASIC

Since the existing VitaGuard® VG1000 and VG2000 are already implemented in SMT andtechnology on printed circuit boards, the next available step in this progression was systemintegration. The FPGA’s, as already used for the existing devices were deemed unsuitablefor the project since they do not offer the possibility of integrating both analogue and digitalcircuitry in one chip.

The second possibility would have been to implement the VitaGuard® circuitry using a multi-chip module (MCM). In this case, individual dies are bonded onto a carrier substrate, whichconnects the individual dies with each other, and the complete module is placed inside acasing. The final appearance is like any other IC. The main advantage with this system isthat the individual dies are already pre-tested. However, three main problems rendered thissolution impractical for the project at hand. The first drawback is that the number ofindividual dies would have been high (over 30). The second factor was the price. Theproduction costs are high compared to an ASIC solution. As an example, a Berlin companycharges 0.035 euro per bond. If GeTeMed assume 30 dies with an average of 16 bonds perdie, then bonding alone would have cost 0.035x30x16 = 16.8 euro. The costs for the carrierand the package need to be added to this. Although this factor is always open toargumentation, the third factor was the decisive factor. An assessment of the presentVitaGuard® circuitry came to the conclusion that not all the necessary dies are commerciallyavailable.

The gate array possibility also had its drawbacks. This technology only allows very limitedintegration of analogue components. Also, the split power-supply problems included in thedesign could not be realised. The gate array solution also suffered from the fact that theintegration density is not sufficient for the project.

The design methodology selected, therefore, was the classical full-custom standard cellapproach. In order to keep the design risk at a minimum, components were taken fromstandard libraries whenever possible. The analogue circuitry and the analogue-to-digitalconverter have been designed as transistor circuits using network analysis software.

The choice of technology was CMOS, as it is cheaper for the implementation of the digitalcircuitry. CMOS offers low-power, high speed and high noise immunity features. Gallium-Arsenic technology is unrealistic for the design as it is the most expensive technology and isusually only used for special purpose, high frequency designs. An analysis of the designyields the following silicon area:

Digital filters 9,0 mm2

SRAM 2,5 mm2

Glue logic 1,5 mm2

Gain stages and ADC 4,5 mm2

Miscellaneous 0,5 mm2

Total core 18 mm2

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Bonding area (pads) 8 mm2

Total silicon 26 mm2

A core area of 16mm2 corresponds to an actual silicon wafer area of approx. 26mm2. Thepackage is a 120 pin QFP package. The complete IC costs around 7.5 euro. In comparison,the present costs of the individual circuit components now integrated amount to 50 euro. Asa rule of thumb, this amount can be multiplied by the factor 3 to account for purchasingcosts, placement and soldering costs, and all the other overhead costs associated with theseindividual components. However, the introduction of the ASIC also enables the realisation ofthe complete VitaGuard® design using a smaller PCB with a lot less components thus savingplacement and soldering costs, test costs and overhead costs. All in all, GeTeMed estimatesa reduction in manufacturing costs of 40% and is convinced that the choices of methodologyand technology are justified by these savings.

The test procedures are performed using the most modern test methods available. Thefollowing test modes were implemented in the ASIC design:

digital scan testdigital functional testanalogue scananalogue scan valid data

When activated using the test select pins, these modes allow access to the various analoguestages as well as the digital filter registers so that they are available to the outside world.

The digital part of the ASIC was done by GeTeMed, using VHDL entry and synthesis. Theanalogue part was specified by GeTeMed and implemented mostly by the subcontractor,since analogue design requires expensive and complex design tools, which were onlyavailable at the subcontrator. Digital and analogue functionality was simulated intensively.The actual test however, only was done with availability of the ASIC. Typically, a redesign isrequired if analogue components don’t work as specified, which often is the case for verysophisticated parts or high speed, noise or resolution requirements. In order to anticipatesome problems, only well known analogue components that already have been verified bythe subcontractor in other projects. However, this may not be possible in every case. Inaddition, the interface between analogue and digital part of the ASIC was made availableexternally, such that parts that would not work properly could have been replaced byexternal components.

8. Expertise and experience in microelectronics of the company and the staffallocated to the project

Prior to starting the FUSE Application Experiment, all of GeTeMed’s hardware circuitdesigns had been accomplished using standard electronic components. One area in whichGeTeMed already had a considerable amount of experience was in the design of printedcircuit boards. However, apart from knowledge gained through reading literature, GeTeMedhad no practical experience in the design of full-custom integrated circuits.

Although simulation tools had been used to a limited extend in their linear analogue designs,GeTeMed had no experience in the realm of digital simulation. GeTeMed was therefore afirst users in the areas of ASIC design and simulation tools. The company has expertise inanalogue and digital hybrid hardware designs such as low-frequency analogue circuitry,ECG amplifier design, microprocessor circuitry (mainly Z80, 8051 and 80C535), standard

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logic circuitry, battery operated power supply designs, DSP technology (ECG analysissystems), PCB design as well as PC programming skills under both DOS and WindowsTM.

The engineer designated to the project had already 5 years work experience with thecompany, but as already mentioned, none in the field of ASIC design.

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9. Work plan and rationale

The original work plan, except during the fabrication phase, planned that one employee fromGeTeMed and one employee from MAZ-Brandenburg continuously work on the project.Also, one employee from each company was involved in technical management. Thesubcontractor and to a certain extend the TTN presented the options of the individual designtasks and GeTeMed took the decision, based on the technical recommendation of theexperts and the experience from our application domain. This close co-operation assuredthat aside the knowledge acquired at basic training measures and from the TTN alsopractical knowledge was built up at GeTeMed. Prior to project start-up possible risks offailure were assessed. Typically a number of redesigns of mixed-signal ASICs is requireduntil full digital and especially analogue functionality is assured. Here, GeTeMed tookprecautions with respect to the ciruit and contracts with the subcontrator. Furthermore, thefirst ASIC was done as a multi project wafer (MPW) with significantly lower engineering cost.

The project was divided into 5 main task phases as follows. The effort of GeTeMed is givenin person days, the subcontractor effort is given in k . Numbers in brackets show theplanned effort:

Task W1: Specification and feasibility analysis

During the first phase of the project, the present VitaGuard® system was analysed and afinal decision made as to what components of the present system should be integrated. Thespecifications for the ASIC design was then draw up.

Duration: 8 weeksManpower: 1 GeTeMed employee 40 (60)person days

1 subcontractor employee 10.8 (11) k

GeTeMed task: Deliver a complete circuit diagram of the present system and explain therequired functionality.

Subcontractortask:

Analyse the circuit and determine exactly what sections can beimplemented. Explain in detail to the GeTeMed employee any limitationsand the reasons why some sections may not be implemented. Findsolutions to these problems.

Task W2: Analysis and simulation

The circuit design was transferred to the design software system and a complete simulationof the circuit performed.

Duration: 16 weeksManpower: 1 GeTeMed employee 80 (140) person days

1 subcontractor employee 21.6 (4.5) kMilestone #1: Circuit design at transistor level complete

GeTeMed task: Define the simulation inputs and outputs. This phase was used to learnhow to operate the simulation software and find out what simulationsystems are available.

Subcontractor Simulate the design and explain to the GeTeMed employee all the

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task: important points that need to be considered during simulation.

Task W3: Layout phase

At this stage of the project, the manual layout and verification process using Cadence toolswas performed.

Duration: 10 weeksManpower: 1 GeTeMed employee 50 (130) person days

1 subcontractor employee 13.5 (22) kMilestone #2: Tape-out i.e. data for the silicon manufacturer complete

GeTeMed task: This phase was used to learn as much as possible about the variouslayout techniques, about the software available and about the choice oftechnology.

Subcontractortask:

Layout the design and explain to the GeTeMed employee all theimportant aspects that need to be considered during the layout phase.Most of the layout was performed by the subcontractor. Layout of theSRAM section was carried out by the silicon manufacturer AMS.

Task W4: Fabrication phase

The fabrication was a multi-project wafer (MPW). The size of the silicon wafer was 26mm2 .AMS manufactured the wafer and delivered completely packaged prototypes. Theproduction time was 12 weeks.

Duration: 12 weeks 20 (13) k

GeTeMed task: The GeTeMed employee used some of this time to learn aboutfabrication methods, technologies used and prepare a list of availablemanufacturers and their conditions.

Task W5: Test phase

The delivered wafer was completely tested and analysed. The test pattern and test strategywas kept in mind throughout the total design process (e.g. test modes in the ASIC).

Duration: 10 weeksManpower: 1 GeTeMed employee 50 (50) person days

1 Subcontractor employee 13.5 (7.5) kMilestone #3: Prototype complete

GeTeMed task: Assist the MAZ-Brandenburg employee during test phase and learnabout the various test methods.

Subcontractortask:

Test the design completely and explain the test rules to the GeTeMedemployee.

As can be seen from the comparison work plan on the next page, the project needed to be

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extended. The phases marked with O show the original plan while the phases marked with Adepict the actual time plan. The subsystem level design phase was extended due mainly tothe fact that the MPW runs do not take place very often. The originally planned tape-out forApril/May could not be adhered to. It was decided to carry out further simulations of thecomplete ASIC (analogue and digital together) in order to keep risks at a minimum and takepart in the MPW run at the beginning of August.

The other phase which took longer than expected was the test setup phase. The reason forthis was that two printed circuit boards needed to be developed in order to perform testing.One PCB was needed as an interface between the 120-pin test socket and the Hewlett-Packard HP82000 digital tester in order to pre-test the prototypes. The second PCB wasdesigned to carry out complete functional testing and was basically a test version of theplanned VitaGuard® monitor with LCD display, microprocessor, EPROM, keyboard and soon. The development of both of these boards took longer than anticipated. All other phaseswere completed within the planned duration.

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O = original time planA = actual time plan

10. Subcontractor information

The subcontractor chosen to accompany the project was MAZ-Brandenburg. Thesubcontractor is both a research and service center, is partly owned by Land Brandenburg

ActivitiesMonths

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

1. Management

Projectmanagement

OA

OA

OA

OA

OA

OA

OA

OA

OA

OA

OA

OA

OA A A A A A A

Dissemination O OA A A

ReportingA A A A A A A A A A A A

OA A A A A A A

2. Specifications

Functionalspecification of

systemA

OA

Systemspecification of

component

OA

OA

Technicalspecification of

component

OA

3. Training

Managementtraining

OA

Specificationtraining

OA

CAD training OA

OA A

Design training O OA A

Evaluation training O OA A

4. Design

System leveldesign

O OA A

Subsystem leveldesign

O OA

OA A A A A

5. Evaluation

Prototypeproduction

O O OA A A

Test set-upA

OA A A A A

Functional testing OA A

Prototype testing OA A

Field testing O OA A

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and is a member of the North German microelectronic group, which was formed to promotethe future development of the microelectronic industry.

In the service area, the subcontractor specialises in full-custom ASIC designs andpossesses all the CAE tools required for such designs coupled with years of practicalexperience. Over 60 full-custom analogue, digital and mixed mode projects have beencompleted to date, the customer spectrum covering both industry and research institutes.While BiCMOS is the technology most commonly employed (which was a definite advantagefor the project at hand), the subcontractor also has experience with high-speed bipolar andGaAs designs.

As can be seen from the brief description given above, the subcontractor was mainly chosenas a result of their proven experience in the field of ASIC design. Other reasons thatgoverned the choice include their location (MAZ-Brandenburg is situated only 25km fromGeTeMed), their close contacts with the silicon foundry and the assurance of supply due totheir company structure.

The contract with MAZ-Brandenburg included a non-disclosure agreement so that the exactcontents cannot be discussed here. However, the contract was straight-forward, held nopitfalls or penalty clauses. The contract contained passages about confidentiality, projecttiming and milestones, engineering samples, warranty, guarantee of delivery conditions andthe rights of each partner in the event of a dispute. One important aspect of the contract wasthe clause that MAZ-Brandenburg remove any defects in the ASIC should it not meet thespecifications laid down by GeTeMed. Should MAZ-Brandenburg fail to do this within areasonable period of time, GeTeMed had the right to demand a reimbursement of costs or,in the worst case, to terminate the contract.

11. Barriers perceived by the company in the first use of the AE technology

As a company which had no previous experience in ASIC design GeTeMed obviouslysuffered to some extent from all the barriers associated with this technology. However, themain barriers perceived were as follows:

Knowledge barriers:The main knowledge barriers were the lack of knowledge about the technology to chooseand the lack of knowledge about the associated costs.

Cultural and inertia barriers (psychology):The high-risk concept was the main psychological barrier to implementing a completely newtechnology and the question as to whether the company can master the task.

Technology barriers:The technological barrier centered around the question as to whether the companypossessed to necessary skills to complete the project

Financial barriers:The main financial barrier to overcome were the cost of development (time, personnel,equipment) and the costs in the production of sufficient ASIC’s for production.

12. Steps taken to overcome the barriers and arrive at an improved product

Knowledge barriers:

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Although GeTeMed had no previous experience in ASIC design, the knowledge barrier canbe easily overcome. By reading engineering/technical publications one comes acrossenough advertisements from companies that offer all sorts of services including ASICdesign. If one is interested, then one only needs to ring up a number of them, makearrangements to meet and discuss the proposed design, ask for a reference list of previousprojects and so on. Within a short time it is possible to gain an overview of the servicesavailable and make a decision. GeTeMed had luck in this respect in that an employee withinthe company already had contact with the subcontractor. They were able to answer anyquestions that GeTeMed had and, through their broad experience in this area, knew all thetricks of the trade. Together with the subcontractor GeTeMed worked out a time plan,decided on the technology (CMOS) to be used, worked out cost estimates, discussed therisks involved and made up contingency plans.

Cultural and inertia barriers (psychology):The high-risk concept is definitely a barrier to implementing a completely new technology.However, the trend world-wide is to miniaturise components and systems so that a companyinvolved in the design and manufacturing of electronic equipment cannot oversee the needto get involved with this form of technology as soon as possible. In other words, marketpressures force one to overcome any cultural or inertia barriers.

Technology barriers:The technological barrier was overcome through the subcontractor. They have all thenecessary tools and personnel needed to solve any problems in this respect. Throughlearning by doing the GeTeMed gained enough experience in this field to carry out futureprojects without assistance. Another possibility is to employ someone who has hadexperience in the field.

Financial barriers:Whether the financial barrier has been completely overcome still remains to be seen. Afinancial assessment of the AE can then be made when the finished product is ready and themarket impact is clear. However, all estimates point to the conclusion that a return ofinvestment will be made by selling 400 units and that this is feasible well within a one yearperiod.

No major technical problems occurred throughout the duration of the project. The MPW runsturned out to be less frequent than expected so that the duration of the project had to beextended by three months. Section 9 shows the revised project time plan.

13. Knowledge and experience acquired

After completing the proposed project, GeTeMed has gained an in-depth understanding ofthe steps and conditions necessary to carry out future projects incorporating integratedcircuit designs. GeTeMed now is capable to specify and simulate a mixed signal project onits own. In order to accomplish this feat, one of its employees was made responsible for theproject and, as technical manager, was given the task of supervising and co-ordinating theproject. As far as GeTeMed is concerned, the best way of gaining knowledge is to stay at thesource. To this effect, it was agreed with the subcontractor that their employee be activelyinvolved in all stages of the project and travel to them on a regular basis (the subcontractoris less than 30 minutes away by car). The advantage of the project was that it involved bothdigital and analogue design. After completing this project GeTeMed is in the position to usethe commercial software tools available to develop, simulate and define the specifications foreither analogue, digital or mixed-signal ASIC designs. Since GeTeMed is not in the positionto work directly with silicon, future designs should be independent of any particulartechnology i.e. GeTeMed should be able to bring the design to the stage where it can be

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handed over to a design center which then performs the layout generation and verificationbased on the technology most suited to the design. The design center would also have allthe equipment and software necessary for testing and processing the silicon as well asmanufacturing the final product. Thus, it is of vital importance that GeTeMed used thisproject as an opportunity to learn the ins and outs of the hardware description languageVHDL.

The experience gained from completing this project will also help GeTeMed when planingnew products. They will be able to accurately predict both design times and costs as well asdraw up better product specifications. Based on the experience acquire by taking part in thisproject, GeTeMed may consider designing a second ASIC for its ECG product line. Thesolid-state Holter recorder could easily be adapted to accommodate an ASIC. Similarly, therest ECG system could also be implemented with an ASIC. The topology of both of thesesystems is similar to that of the baby monitoring products i.e. an analogue signal is detected,filtered, amplified, converted and stored in memory. Also, both of these systems need to besmall and compact. The great advantage of the ASIC design developed within the FUSEproject is that it covers the topology that all GeTeMed’s future systems require. Theknowledge acquired throughout the AE can be broken up as follows:

- Management training- Specification training- CAD training- Design training- Evaluation training

Management training was very important in helping to plan and co-ordinate the project. Thespecification training took place at the subcontractor and involved defining parameters suchas input and output variables, operating conditions, timing requirements and so onnecessary for defining the specifications of the ASIC. CAD training ran parallel to the wholedevelopment and involved learning how to use modern development tools such as Matlab(for determining the coefficients of digital filters), Modeltech (for VHDL simulations),Synopsis (for synthesis of the VHDL description of the digital design) and Cadence (foranalogue simulation and layout). Design training encompassed the skills necessary forplacing analogue and digital parts in such a way that they do not interfere with each other,the construction of integrated ohmic resistances, how to eliminate offset effects, how toposition the bonding areas as well as the properties of input and output buffers. Evaluationtraining included knowledge on how to perform VHDL simulations and interpret the results.All in all, GeTeMed is now in a position to carry out a similar project in the future without anyguidance from a design center.

14. Lessons learned

No major difficulties were encountered throughout the project. The reason for this is thatGeTeMed had a very experienced and competent subcontractor. The project was extendedfor 3 months but this was mainly due to the fact the MPW runs at AMS do not take placevery often. Instead of rushing for an earlier MPW date, it was decided to wait for the next oneand spent the time usefully by carrying out more simulations of the design. The majorchange in the design over the original proposal was to leave out the 8051 microprocessorcore since the license fees were higher than originally estimated. As this decision was madeat the beginning of the project, no delays or extra costs were incurred as a result. One otheroriginal idea that was not implemented was a real-time clock (RTC) functions. This could notbe implemented because it would have involved a quartz and an extra power supply in orderto keep the time when the rest of the ASIC is not powered. Since small RTC’s are readilyavailable on the market, the extra difficulties encountered in integrating such a function

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would not have brought sufficient cost returns.

15. Resulting product, its industrialisation and internal replication

The key components of GeTeMed’s systems are small, battery powered, portable devicesthat utilise both analogue and digital technology. The trend nowadays is not just tominiaturise systems but, at the same time, to increase their complexity. The only possibleway of keeping up with this trend is through circuit integration. It is therefore a necessity thatthe GeTeMed gains sufficient knowledge of integrated circuit design in order to be able torepeat the process again in the near future and keep, or even better, improve, their positionwithin the market. Other companies in the area of medical electronics are also faced withthese problems. System complexity, however, is not the only reason forcing companies totake the step towards system integration. Space utilisation is also a key factor, and this isespecially true in the hospital environment. The amount of equipment in hospitals hasincreased dramatically over the years and many hospitals, especially older ones, haveproblems finding space for all the equipment. Medical devices are often moved from bed tobed or from ward to ward, or the patient physically needs to carry the equipment on a dailybasis. Such equipment therefore needs to be light, compact and robust. Circuit integration isthe only way towards meeting these goals. A short glance in any medical equipment journalor magazine will confirm this trend. It is proposed that the finished product incorporating theASIC look as follows:

The choice of foundry was AMS in Erfurt. AMS has experience in both CMOS and BiCMOS,is prepared to manufacture small quantities and offers the added advantage that it is nearby.The subcontractor (MAZ-Brandenburg) has assured GeTeMed that AMS offers fair prices for

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MPW runs and that their dealings with this company to date have been very positive.

The ASIC was tested using both a digital tester (HP82000) to perform simulated runs of theASIC functions and to check the timing parameters as well as with a test VitaGuard® PCBcontaining the accompanying microprocessor (SAB80C535). This board enabled thesoftware necessary for communication with the ASIC to be developed. The integrated testmodes were implemented on the digital tester to check all the internal registers and theanalogue section of the ASIC. Following this, the ASIC was tested using the VitaGuard® testPCB.

The 19 control registers were tested first. To check that the values written to the registerswere excepted, an array of LED’s was used on the test board. These LED’s were connectedto the ASIC’s latched outputs. It was possible to write information correctly to these registers.

The RR interval counter was tested next. A 2Hz pulse was used as the input to the counter.The correct value of 120 BPM was calculated from the results produced by the RR countercircuitry. This procedure was repeated and verified for 30 BPM (0,5Hz) and 60 BPM (1Hz).

The output registers (output of digital filters and RR counter) were tested while testing theRR counter and during the test phase of the analogue section. All output registers deliveredthe expected values.

The chip-select logic (address decoder) was then checked. As it was possible to write datato the LCD display on the test board, this implied that the logic functioned accordingly (theLCD has 3 controllers and therefore needs 3 chip-select lines). The signals were alsocontrolled and measured optically on an oscilloscope. The interrupt and reset logic wastested and functioned correctly. An 8ms repetition rate was programmed and correctlymeasured.

The analogue section was pre-tested during the functional testing phase. The results wereverified using the test VitaGuard® PCB. The offset calibration was first checked bydeveloping a calibration routine. This involved setting the calibration flag which short-circuitsthe analogue inputs and then applying values to the offset registers. The outputs of theanalogue chains were then read from the output registers. It was possible to compensate forinternal offsets and yield a centered base-line. The multiplexer and programmable gainamplifier (PGA) were then tested. A square-wave signal was applied to each amplifier inputseparately. The outputs were again read from the output registers and displayed on the LCDdisplay. As the applied signal only appeared on the LCD corresponding to the channel towhich it was applied, this showed that the multiplexer functioned correctly. The gain wasvaried for each channel to verify that the PGA operated.

The digital filter section was tested last as this is the most complicated part of the ASIC. Thecoefficients for the four band pass filters (ECG, QRS, respiration and artefact) were writtento SRAM and the filter started (by means of the start flag in the control registers). A squarewave was applied to all the inputs simultaneously and the outputs analysed. By examiningthe timing characteristics of the output signals (rise time and slope), the upper and lower cut-off frequencies were verified. The values obtained corresponded well with the expectedvalues.

To realise the end product, the ASIC needs to be fully embedded into the VitaGuard®

monitor. This involves building a further prototype of the complete system, rearranging thecomplete software and performing all the necessary verification and validation steps inaccordance with the MDD 93/42/EWG regulations before the system can be put on themarket. From experience, the design and regulatory steps take at least a year to complete.

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The additional costs for this may amount to as much as the development costs.

After successful market introduction and first experiences in the market, GeTeMed plans toevaluate its other products for possible improvements with ASIC or mixed-signal ASICtechnology.

16. Economic impact and improvement in competitive position

The VitaGuard® turnover for 1995 was 0.85 million euro and increased to 1.3 million euro in1996. Over the last three years GeTeMed has steadily built up an agent network so that itnow has agents covering practically all parts of Germany. These agents demonstrate thesystem to the doctors and nurses, deliver the monitors to the hospitals, teach the parentshow to use the monitor and offer 24 hour customer service when parents are havingdifficulties. Although GeTeMed now also has agents in Austria and Switzerland, the nextstep is to expand into the rest of Europe.

The main reason for taking part in the FUSE programme was to bring about a noticeablereduction in the costs of producing the monitor. A cost analysis of the electronic componentsin the original system showed that they accounted for over 50% of the total manufacturingcost. Such parts included logic IC’s, operational amplifiers, VMOS switches, resistors,capacitors and so on. Due to the ASIC a large portion of these components are no longerneeded. Also, it will be possible to construct the new VitaGuard® with one smaller PCBwhich is also a major cost factor. GeTeMed estimates that the costs of the electroniccomponents will be reduced by about 50% i.e. the price of the ASIC will be about half theprice of the individual components now integrated. The actual cost reduction, whenpurchasing, transport and other overhead costs are taken into account, is expected to be inthe region of 40% per system.

System reliability and future maintenance costs will also be reduced as a result of the large-scale integration and the simpler system construction. It is estimated that the sum investedwill be returned after selling the first 400 systems. As it is expected to sell at least 1000 unitsper annum, the payback period is well under one year. With an overall lifetime of at least fiveyears a return on investment of over 500% can be expected. The second main advantage ofimplementing an ASIC solution is that the danger of the system being copied by othercompetitors is vastly reduced.

One factor that has undoubtedly contributed to GeTeMed’s success so far is the fact that theGerman and Austrian national health systems actively support home monitoringprogrammes. Unfortunately, there are no other such programmes throughout the rest ofEurope. The market, however, is crying out for a monitor that can be purchased for areasonable price. GeTeMed actively participates in nearly all the medical trade shows andsymposiums throughout Germany (e.g. „Medica“ in Düsseldorf and the „Interhospital“ inHannover). These events are always strongly attended by members of the medicalprofession from other European countries. The reaction to the baby monitoring systems isalways extremely positive. GeTeMed also regularly receives requests from medical supplierswho have been given the task of furnishing complete hospitals, especially in former Easternblock and Arabic countries. The problem, however, at the end of the day, is that prices aretoo high. This situation is very frustrating. There is a big market throughout Europe for suchproducts, but a further price reduction of the present system is not possible. Wage costs andsocial security contributions in Germany are among the highest in Europe so that there islittle scope for price reductions.

The European market can be split into two sectors: the VitaGuard® sector, where combi-monitoring (respiration and heart rate) similar to Germany is the general practice, and the

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BabyGuard® sector, where respiration monitoring alone is considered sufficient. This lattersector offers a large economic potential. Most former East European countries are presentlycoming to terms with the changed political situations and are only now starting to invest intheir public health systems. While VitaGuard®, even with the ASIC, would still be tooexpensive in most cases, the BabyGuard® monitor could be redesigned to produce a simple,reliable apnea monitor that could be sold at a reasonable price. Because all of the circuitry isintegrated, this high-quality system, coupled with GeTeMed’s twelve years of experience inthis area, would not loose any of the finesse of the present system and would be of greatbenefit to all concerned. The only way to break into these markets, however, is through areduction in the manufacturing costs of the baby monitoring products and this, as alreadymentioned, can only be achieved by applying large scale integration techniques. A secondreason why costs need to be reduced before moving into the wider European market is thatoverhead costs increase with distance e.g. transport costs and costs associated withmeeting agents on a regular basis. To summarise, consider the following sales figureprojections:

GeTeMed implements the ASIC into VitaGuard® and absolutely nothing else changes. As aresult, GeTeMed stays permanently rooted in the home monitoring market. The yearlyrequirement would be around 1000 pieces per year. While this figure is very low in the eyesof the average IC manufacturer, it still represents a sales volume of around 1.3 million euro(end user price of approx. 2.2 million euro), so that even in this worst case scenario, apositive return of investment within a one year period is realistic.

0

500

1000

1500

2000

1996 1997 1998 1999 2000 2001

Current product Improved product

A further option of the new technology is development of a VitaGuard® to include a pulseoximeter module. This situation opens new possibilities in the hospital market and increasesthe yearly IC requirement to around 1400 pieces. Since GeTeMed would sell the VitaGuard®

with pulse oximeter at a higher price, it now would have a yearly sales volume ofapproximately 2 million euro (end user price of approx. 3.5 million euro).

The third possibility is that GeTeMed develops the pulse oximeter version described aboveand also develops an export BabyGuard® model (with ASIC) selling at around 250 euro. Aconservative estimate would be around 1000 such BabyGuards® per year. The yearly ICrequirement would then be around 2500 pieces with a corresponding yearly sales volume ofaround 2.3 million euro (end user price of approx. 3.9 million euro).

The three examples above demonstrate one point . Although the yearly IC requirement willnever be very high, the associated sales volume does ensure that a positive return ofinvestment is realisable. Also, through use of the ASIC, the profit margin per monitor forsome configurations can be increased by reduction of production costs of up to 250 whichstrengthens GeTeMed’s position in relation to its competitors considerably.

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17. Target audience for dissemination throughout Europe

The special information that can be drawn from this application experiment is the higheconomical potential of mixed-signal ASICs even at low numbers. Therefore, companieswith products to improve with mixed-signal ASIC technology should not be discouraged bysemiconductor companies, which often only head for the large numbers.The information to be disseminated at seminars run by the TTN will include an introductorytalk about how the VitaGuard® monitor operates, why it is used (i.e. to combat the suddeninfant death syndrome) and where it is used (both in clinics and home monitoringprogrammes), followed by a more technical explanation of the inner workings of the system.As our company know-how is contained in the software algorithms implemented to recognisethe respiration signal, we would have no qualms about disclosing the hardware circuitrycontained within the VitaGuard®. A comparison will then be draw between the presentsystem and the new design incorporating the ASIC resulting from this project, demonstratingclearly the advantages gained by using this new technology.The results may be of interest in the PRODCOM domain 33 (Precision instruments),especially in 3310 (Medical and surgical equipment ...) and 3320 (Instruments andappliances for measuring ...