Agilent Haim S

Analog X-parameters at the System-Level

Haim SpiegelEEsof Israel

Accurate and Convenienttools to achieve RF-BB andESL-RF design flow closure

December 9, 2010

Haim Spiegel1

Outline

Problem Statement: The RF-Baseband Design Gap

What are X-parameters?

How can X-parameters fit into System-Level Tools?– Tools Used : Agilent EEsof ADS and SystemVue

Case study Based on Power Amplifier X Parameter model1. QPSK Modulation2. Radar Example3. Tunable Non-Linear Notch Filter4. Digital Predistortion

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Problem Statement : The RF-Baseband Design Gap

Traditional BB tools for communications algorithm and digital signal processing do not account well for

– RF models, RF effects, Measurements, Wireless and specialized IP

Dedicated RF tools do not easily support baseband algorithm and hardware development

Need a creation tool that helps with RF-Baseband cross-domainarchitectures, diagnostics, and partitioning :

– “Where is the least expensive place to solve a particular problem?” – “What is the root cause of link-level performance issues?”– “What is my actual design margin?”

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Levels of Abstraction for Physical Layer modeling

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System-level Physical Layer(Dataflow)

RTL simulators

Analog/RFEnvelope

Analog/RFTransient

TIME DOMAIN

Analog/RFFreq domain

Logic Analyzer

Vector Signal Analyzer

Oscillo-scope

Spec/Network Analyzer

MODULATED FREQ DOMAIN

EmulatorsAccelerators

Abstraction to time domain

Logic Block-levelControl, behavioral

RF Block-level

DESIGN FLOW GAP

AlgorithmMath, FXP

HLS, Embedded

Hard-ware

Physical

Func-tional

Data-streams

SystemVue: a cross-domain, ESL approach

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System-level Physical Layer(Dataflow)

RTL simulators

Analog/RFEnvelope

Analog/RFTransient

TIME DOMAIN

Analog/RFFreq domain

Logic Analyzer

Vector Signal Analyzer

Oscillo-scope

Spec/Network Analyzer

MODULATED FREQ DOMAIN

EmulatorsAccelerators

Abstraction to time domain

Logic Block-levelAlgorithmMath, FXP

Control, behavioral

RF Block-level

Hard-ware

Physical

Func-tional

Data-streams

THIS PRESENTATIONSystemVue

HLS, Embedded

Outline


Extraction and Verification

How can X-parameters fit into System-Level tools?

6

Haim Spiegel

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What are X-Parameters?

X-parameters are the mathematically correct nonlinear superset of S-parameters, applicable to both large-signal and small signal conditions, for linear and nonlinear components

• Measure nonlinear behavior• Extract a model Measure or Generation by Simulator (ADS)• Simulate in Agilent ADS, SystemVue (Spectrasys), and Genesys

Haim Spiegel

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X-parameters come from the Poly-Harmonic Distortion (PHD) Framework

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X-parameters exhibit full loadpull & bias variations

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Agilent EEsof Platform support for X-parameters

NVNA(Meas-based extraction)

W2305 X-parameter (Sim-based extraction)

ADS 2009 U1

ADS

Harmonic BalanceCircuit Envelope

RuntimeX-parameter

Usage(NOT LICENSED)

X-parameterGeneration/Extraction

(LICENSED)

X-parameter File Format

ADSGenesys2010.05

SpectrasysHarbec

SystemVueSV2010.07

W1719 RF System Design Kit

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Haim Spiegel

Agilent NVNA & X-Parameters

A new paradigm for nonlinear RF component measurements, modeling, and simulation

The most innovative instrument from

HP/Agilent in 25 Years!

Measures magnitude and phase of all relevant frequency components necessary to measure X-parameters

More information (app notes, videos, papers, links)http://www.agilent.com/find/x-parameters

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Outline

• Power Amplifier

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PA Circuit in Cadence to ADS for X-parameter Generation

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X_Parameter ADS Template Generation

X_Parameter File

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Verification of X-parameter in ADS

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IN ADS, comparison of Circuit vs X-parameter

Verification of X-parameter in SystemVue

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In SystemVue, comparison of Circuit vs X-parameter

Outline

Haim Spiegel

December 9, 2010

• What is X Parameter• Generation of X Parameter of a Power Amplifier•Versification of X Parameter in Simulation tool

•ADS Advanced Design System•SystemVue

NEXT •How can X-parameters fit into System-Level tools?

How can X-parameters fit into System-Level tools?

1-DSP and RF X-parameter Simulation SetupIn SystemVue

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1-SystemVue –Custom DSP Code

• Software platform directly reads Math code enabling a variety of applications

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1-RF Model Link X-parameter

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1-Simulation Results of DSP with/without RF model

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2-SystemVue Radar System Simulation

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2- Radar Antenna System

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X-parameter can be used for PA model

2-Radar System Signals

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2-Radar System Post Process Signals with Mathlang

MTD

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2-Post Process Signals with Mathlang CFAR

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2-Radar Detected Signal After Processor

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Outline

NEXT3. Tunable Non-Linear Notch Filter

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• What is X Parameter• Generation of X Parameter of a Power Amplifier•Versification of X Parameter in Simulation tool

•ADS Advanced Design System•SystemVue

•How can X-parameters fit into System-Level tools.•QPSK example

3-Non Linear Notch Filter RF System

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Tunable RF notch filter

This circuit demonstrates: – Frequency-dependence– Power-dependence– Harmonic generation– Severe mismatch into

50Ω termination

Series RLCTANK

RESONATOR

SIMPLE VARACTOR

MODEL

DC

IN OUT

3-Linear S-parameter Frequency Response vs. Bias

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110 120 130 140 150 160 170 180 190100 200

-20

-15

-10

-5

-25

0

freq, MHzdB

(S(2

,1))

dB(S

(1,1

))

freq (100.0MHz to 200.0MHz)

S(1,

1)

Tune the DC Bias05 volts

Notch frequency 133MHz 168MHz

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3-Nonlinear performance (using harmonic balance)HB simulation must be set up before the X-parameter extraction

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Fundfreq=dBm(Vout)=-2.370

145.0MHzH2ind Delta=dep Delta=-42.340Delta Mode ON

1.450E8

0.2 0.4 0.6 0.8 1.0 1.20.0 1.4

-90

-80

-70

-60

-50

-40

-30

-20

-10

-100

0

freq, GHz

dBm

(Vou

t)

Fund

H2



1.450E8

2 4 6 8 10 120 14

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

-1.0

1.0

time, nsec

ts(V

out),

V

STARTS FORWARD BIASING AT APPROX+10dBm INPUT PWR

MILDLY NONLINEARAT +0 dBm INPUT PWR

THE NOTCH FREQUENCY TUNES AWAY FROM NONIMAL AT HIGHER POWER LEVELS…how much?

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Pin=0dBm

Pin=-20dBm

3-Final circuit-level performance“What should we see when we export to the system-level?”

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1.450E8

0.2 0.4 0.6 0.8 1.0 1.20.0 1.4

-90

-80

-70

-60

-50

-40

-30

-20

-10

-100

0

dBm

(Vou

t)Fund

H2



1.450E8



1.600E8

0.2 0.4 0.6 0.8 1.0 1.2 1.40.0 1.6

-90

-80

-70

-60

-50

-40

-30

-20

-10

-100

0

dBm

(Vou

t)

Fund

H2



1.600E8



1.600E8

0.2 0.4 0.6 0.8 1.0 1.2 1.40.0 1.6

-90

-80

-70

-60

-50

-40

-30

-20

-10

-100

0

dBm

(Vou

t) Fund

H2



1.600E8Fundfreq=dBm(Vout)=-22.330


1.450E8

0.2 0.4 0.6 0.8 1.0 1.20.0 1.4

-90

-80

-70

-60

-50

-40

-30

-20

-10

-100

0

dBm

(Vou

t)

Fund

H2



1.450E8

Freq=145MHzH2=-42.34dBc


In the notch

Freq=160MHH2=-13.96dB

In the notch


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3-Extracting X-parametersNow start adding complexity and detail

Case 2: Finer sweep– 5 harmonics– DC=0.85 4.85volts, 5pts– Freq=130 170MHz,21 pts– Power=-30+10dBm, 5pts– File size: 2.5MB

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3-Testing the Circuit_Link X Parameter network in an RF System,Excellent correlation of System vs. original circuit

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1.450E8

0.2 0.4 0.6 0.8 1.0 1.20.0 1.4

-90

-80

-70

-60

-50

-40

-30

-20

-10

-100

0

freq, GHz

dBm

(Vou

t)

Fund

H2



1.450E8

HARMONIC LEVEL

F = 145MHzP = +0 dBm

HB Tone Original SystemVue dBc ± | ΔdBc | Fundamental -2.370 dBm -2.427 dBm 0.0 dBc ± 0.06 dB

Second -44.71 dBm -44.45 dBm -42.3 dBc ± 0.3 dB

Third -77.59 dBm -77.25 dBm -75.2 dBc ± 0.4 dB

3-Extracting X-parametersExternalizing a DC bias pin in Spectrasys

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Adding a DC port to the X-paramextraction produces an external DC pin in Spectrasysfor sweeps/tuning DC PIN

3-Verifying the DC tuning pin MultiToneTune the “DCBias” variable, and the Notch center freq. moves

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“DCBias=0.85”

“DCBias=1.85”

“DCBias=2.85”

“DCBias=3.85”

3-Cascadability of devices within Circuit_linkSpectrasys preserves harmonics, load-pull sensitivity, etc

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CIRCUIT_LINK NETWORK WITH 2 NONLINEAR X-parameter PARTS

(in Spectrasys)

2 CASCADED CIRCUIT-LEVEL DEVICES (in ADS)

3-Cascadability of Devices within Circuit_link

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Predicted by Original ADS Circuit

Minimum @ 147MHz-39.0

Maximum @ 155MHz-15.4

Maximum @ 155MHz-39.5

Total VariationPeak vs. Null

23.6dB

Total VariationPeak vs. Null

21.8dB

Predicted by Spectrasys

Peak-to-Peak Variation in Nonllinear Multi-carrier Amplitude

21.8 dB (SystemVue ) vs. 23.6 dB (ADS)

X-parameters are cascadable like S-parameters, accurate like whole circuits, but don’t require the original RF tools or

RF expertise to be used.

3-We believe the X-parameter response. Now, let’s try them in an RF receiver.

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3-X-parameters in a Spectrasys receiver simulation

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NF=5.5dBG=30dB

RFAmp_3 RFAMPRxIFOut *OUT

Circuit_LinkRFin RFout

DesignName='XAmp2Disabled: SHORT

Circuit_Link_1 Circuit_LinkNF=5.5dBG=30dB

RFAmp_3 RFAMPRxIFOut *OUT

Circuit_LinkRFin RFout

DesignName='XAmp2Circuit_Link_1 Circuit_Link

With added Notchat 155MHz (DC=2.3)

3-Spectrasys receiver in a Dataflow simulation(Baseband/DSP using the RF_Link feature)

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Drag & DropDataflow modeling “on the fly”

SPECTRASYS

DATAFLOW

3-Spectrasys receiver in a Dataflow simulation(Baseband/DSP using the RF_Link feature)

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RF INPUT : 3 ADJACENT MODULATED CARRIERS

BASEBAND OUTPUT: ORIGINAL

BASEBAND OUTPUT: With X-param

Outline

Problem Statement: The RF-Baseband Design Gap



Case study Based on Power Amplifier X Parameter model1. QPSK Modulation2. Radar Example3. Tunable Non-Linear Notch Filter

NEXT1. Digital Pre-Distortion

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4- DPD –Digital Pre Distortion

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• Achieves 20dB improvement to extend range, efficiency, battery life; extends life of existing RF xcvr designs

• Increased in-band performance for EVM and throughput

• Configurable 4G test vectors, based on live measurements

• PA Vendor & DSP/FPGA technology-neutral

• UI wizard for easy set-up, with automated extraction

4-Digital Pre-Distortion- Principle

Agilent Restricted- Agilent Copyright 2010

12/9/201046

Actual Amplifier Amplitude ResponseDPD Amplitude Response Linear PA Amplitude Response

DPD PA PA

PA-1

input x y input x

Digital Predistortion function brings in distortions out of phase with those generated by the PA/TRx nonlinearities.

Need to model the PA behavior accurately andefficiently for successful DPD deployment

4-Digital Pre-Distortion- Principle


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Create DPD Stimulus

Capture DUT Response

DUT Model Extraction

DPD Response

Verify DPD Response

Two type of models

•X Parameter Model file•Measurement Based

DPD FLOW

4-Digital Pre-Distortion- Create Stimulus


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Create Stimulus andCreate DUT ResponseOne step.Based on X ParameterRecord Files Output

LTE Library Source example

4-Digital Pre-Distortion- Model Extraction


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Recorded Files from previous step used toCreate the Memory Polynomial PD model

4-Digital Pre-Distortion- Apply DPD


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Record Output spectrum of•PA only•DPD only•DPD+PA

LTE Library Source example

4-Digital Pre-Distortion- Results


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LTE EVM Measurements

LTE ACLR Measurements

OutlineProblem Statement: The RF-Baseband Design Gap



Case study Based on Power Amplifier X Parameter model1. QPSK Modulation2. Radar Example3. Tunable Non-Linear Notch Filter4. Digital Pre-Distortion

NEXT

Conclusion

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Conclusion – Who are these features for?

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X-parameters

RF_LINK

CIRCUIT_LINK

RF Component Designers• Simulation: ADS• Measurement: NVNA

System & Baseband Designers• Simulation: Dataflow• Languages: C++, .m, HDL• Measurement: VSA

SystemVue brings“RF Without Tears”

to System & Baseband Designers

ConclusionSystemVue is a Comms ESL environment that “speaks RF”

Easy Generation of X Parameter from ADS tool

X-parameters and RF_Link provide implementation-based design flow closure to RF, System, and Baseband teams

Digital Pre Distortion Utility to easy DPD design

SystemVue maximizes speed, accuracy, and design flow simplicity for the non-RF audience, who today are including few (or no) RF effects in link-level and block-level dataflow simulations.

EEsof Israel: Avishai Viernik and Haim Spiegel

03-9288509 03-9288514

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Agilent Haim S

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