Pulsed-RF Overview • Pulsed-RF Measurement Techniques · • Pulsed-RF Overview • Pulsed-RF...
Transcript of Pulsed-RF Overview • Pulsed-RF Measurement Techniques · • Pulsed-RF Overview • Pulsed-RF...
1Jan 2009
Agenda
• Pulsed-RF Overview• Pulsed-RF Measurement
Techniques• Wideband/Synchronous • Narrowband/Asynchronous
2Jan 2009
Component-Level Characterization
• Accurate characterization of components such as amplifiers, mixers, filters, and antennas is critical for effective system simulation
• Pulsed-RF stimulus crucial for many components in A/D applications
AMPBPFCOHO
STALO ReceiverProtection
PulseModulator
PRFGenerator
FrequencyAgile LO
DUPLEXORPREDRIVER
AMPRF
BPFPULSEDPOWER
Tx
LNA
IFBPF
0o SPLITTER
ADC
ADC
ANTENNATRANSMITTER / EXCITER
Digital SignalProcessor
(range and Doppler FFT)
Radar DataProcessor
(tracking loops, etc.)
90oCOHO
S/H
S/H
LIMITER
LPF
LPF
BB AMP
BB AMP
LPF
MMI
RECEIVER / SIGNAL PROCESSOR
1stIFA
2nd LO
IFBPF
2nd
IFA
3Jan 2009
VNA’s Measure Effect DUT Has On Stimulus
Measurements are ratioed:• S11 = A/R• S21 = B/R• magnitude and phase
RECEIVER / DETECTOR
PROCESSOR / DISPLAY
REFLECTED (A) TRANSMITTED (B)INCIDENT (R)
SIGNALSEPARATION
SOURCE
Incident
Reflected TransmittedDUT
4Jan 2009
Why Test Under Pulsed Conditions?
• Device may behave differently between CW and pulsed stimuli• Bias changes during pulse might affect RF performance• Overshoot, ringing, droop may result from pulsed stimulus• Measuring behavior within pulse is often critical to characterizing
system operation (radars for example)• CW test signals would destroy DUT
• High-power amplifiers not designed for continuous operation• On-wafer devices often lack adequate heat sinking• Pulsed test-power levels can be same as actual operation
5Jan 2009
Radar and Electronic-Warfare
• Biggest market for pulsed-RF testing
• Traditional applications ≤ 20 GHz
• Devices include• Amplifiers
• T/R modules
• up/down converters
6Jan 2009
Wireless Communications Systems
• TDMA-based systems often use burst mode transmission
• Saves battery power
• Minimizes probability of intercept
• Power amplifiers often tested with pulsed bias
• Most of wireless communications applications ≤ 6 GHz
7Jan 2009
On-Wafer Amplifier Test and Modeling
• Most applications are at microwave frequencies
• Devices lack adequate heatsinking for CW testing, so pulsed-RF used as a test technique to extract S-parameters
• Arbitrary, stable temperature (isothermal state) set by adjusting duty cycle
• Duty cycles are typically < 1%
• Often requires synchronization of pulsed bias and pulsed RF stimulus
8Jan 2009
Pulsed Antenna Test
• About 30% of antenna test involves pulsed-RF stimulus
• Test individual antennas, complete systems, or RCS
• RCS (Radar Cross Section) measurements often require gating to avoid overloading receiver
9Jan 2009
VNA Pulsed-RF Measurements
Average Pulse
Magnitude and phase data averaged over duration of pulse
Point-in-Pulse
Data acquired only during specified gate width and position within pulse
VNA data display
Frequency domain
Frequency domain
Time domain
Pulse Profile
Data acquired at uniformly spaced time positions across pulse (requires a repetitive pulse stream) Magnitude
Phase
data point
Note: there may not be a one-to-one correlation between data points and the actual number of pulses that occur during the measurement
CWdB
deg
Swept carrier
10Jan 2009
Pulsed-RF Data Acquisition (Time Domain View)
t
carrier freq
Trace point 1
Trace point 2
Trace point 3
Trace point 4
Trace point 5
Trace point 6
. . .
Freq 1Freq 2
Freq 3Freq 4
Freq 5Freq 6 . . .
Point-in-Pulse
Pulse Profile
t
gate delay
Trace point 1
Trace point 2
Trace point 3
Trace point 4
Trace point 5
Trace point 6
. . .
Delay 1Delay 2
Delay 3Delay 4
Delay 5Delay 6 . . .
Note: the number of pulses per data point
varies with PRF and IF bandwidth
Pulsed-RF
Gate
11Jan 2009
tData samples
Pulsed IF
Narrowband detection uses hardware switches (gates) in RF or IF path to define acquisition window
Broadband detection uses sampling period to define acquisition window
Point-in-Pulse
acquisition window
Narrowband detection
Broadband detection
Anti-alias filter
ADCIF gate Digital FIR IF filter
Pulsed IF
Anti-alias filter
ADCRF gate
Digital FIR IF filter
Pulsed RF
Defining the Acquisition Window
12Jan 2009
Pulse-to-Pulse (Single Shot) Measurements• Carrier remains fixed in frequency• Measurement point in pulse remains fixed with respect to pulse trigger
(requires wideband detection technique)• One data point for each successive pulse, no pulses skipped• Display magnitude and/or phase versus time
VNA data display Time domain
P1 P2 P3 P4 P5 P6 …
CW pulses
One data point for each successive pulse, no pulses skipped
13Jan 2009
Agenda
• Pulsed-RF Overview• Pulsed-RF Measurement
Techniques• Wideband/Synchronous • Narrowband/Asynchronous
14Jan 2009
fc
Pulse repetition frequency(PRF = 1/PRI)
1/PW
Time domain
Pulse width (PW)
Pulse repetition period (PRP)Pulse repetition interval (PRI)
Carrier frequency (fc)
Measured S-parameters
Pulsed-RF Network Analysis Terminology
Frequency domain
Duty cycle = on time/(on+off time)
= PW/PRI
15Jan 2009
Pulsed S-parameter Measurement ModesWideband/synchronous acquisition
• Majority of pulse energy is contained within receiver bandwidth• Incoming pulses and analyzer sampling are synchronous
(requires a pulse trigger, either internal (8510) or external (PNA)• Pulse is “on” for duration of data acquisition• No loss in dynamic range for small duty cycles (long PRI's),
but there is a lower limit to pulse width
Receiver BW
Pulse trigger Time domainFrequency domain
16Jan 2009
Pulsed S-parameter Measurement ModesNarrowband/asynchronous acquisition
• Extract central spectral component only; measurement appears CW• Data acquisition is not synchronized with incoming pulses (pulse trigger not required)• Sometimes called “high PRF” since normally, PRF >> IF bandwidth• “Spectral nulling" technique achieves wider bandwidths and faster measurements• No lower limit to pulse width, but dynamic range is function of duty cycle
IF filter
IF filter
Time domain
Frequency domainD/R degradation = 20*log[duty cycle]
17Jan 2009
Duty Cycle Effect on Pulsed Dynamic Range(New PNA-X will surpass existing loss tangents)
Wideband detectionHP 8510C Opt 008
Narrowband detection
Dyn
amic
Ran
ge (d
B)
Duty Cycle (%)
100 10.0 1.0 0.1
100
80
60
40
20
0
WidebandDetection
8510
Narrowband Detection PNA
Narrowband Detection 8510
WirelessRadar
Isotherm.
The system dynamic range of the microwave PNA is much better than the 8510C, helping to overcome the limitations of narrowband detection
0.01
18Jan 2009
Agenda
• Pulsed-RF Overview• Pulsed-RF Measurement
Techniques• Wideband/Synchronous • Narrowband/Asynchronous
19Jan 2009
I
Q
Pulsed I/Q
t
Broadband, analog synchronous detector
(BW ≈ 1.5 MHz)
Pulsed Signal Baseband pulsed I/QA/D
converter
I(t)
Q(t)
I
Q
Pulsed I/Q
t
8510 Pulse Measurement Technique(Wideband Mode)
risetime (1/τ) = 300 ns
fall time = 300 ns
20 MHz IF
Pulse trigger
Fast sample/hold
Pulse profile achieved by increasing delay of sample
point
Sample delay
0o
90o20 MHz
20Jan 2009
PNA Wideband Detection in the Time Domain
...
PNA IF filter = 35 kHzPNA sample rate = 6 us/sampleNumber of samples = 5
Pulsed IF
30 us
PNA Samples
External Pulse Trigger
70 us trigger delay
1 2 3 4 5
30 us
1 2 3 4 5
...
...
...
...
...
20 us settling time
30 us acquisition time
20 us settling + 30 us acquisition = 50 us minimum pulse width
(using 35 kHz IF bandwidth)
50 us pre-trigger
21Jan 2009
PNA Wideband Detection – Point-in-Pulse
• Set delay of PNA sampling (relative to RF modulation) to establish desired position within pulse (controlled by pulse generator outputs)
• Width of acquisition window is determined by IF bandwidth
1 2 3 4 5
Pulsed IF
PNA Samples
t
Modulation trigger PNA sample trigger
Point-in-pulse delay
20 us settling time
22Jan 2009
Minimum Pulse Widths for Point-in-Pulse Measurements Using Wideband Detection
Maximum IF bandwidth
Minimum pulse width
IF auto-gain mode*
PNA models(20, 40, 50, 67 GHz) 40 kHz 50 us Yes
PNA-L models(2-port, 20, 40, 50 GHz) 250 kHz 10 us Yes
PNA-L models(2-port, 6, 13.5 GHz; 4-port, 20 GHz)
600 kHz 2 us No
PNA-X models(26.5 GHz) 5 MHz 250 ns No
* Note: for point-in-pulse measurements, the IF auto-gain mode should be turned off (i.e., set IF gains manually)
23Jan 2009
10 MHz Ref
Typical Hardware Setup For Wideband DetectionPoint-in-Pulse and Pulse-to-Pulse using PNA
Output 1
Src OutRef In
Cplr Thru
DUT
Output 2
To TRIG IN (rear panel)
External pulse generator (e.g., 81110A/81111A)
Z5623A H81 2-20 GHz RF modulator
PNA (20, 40, 50, or 67 GHz) with:• 014 Configurable test set• UNL Source attenuators• 080 Frequency offset mode
Note: pulse generator controls timing
Additional PNA setup:• step sweep• frequency offset on (0 Hz)• Auto IF gain = off
24Jan 2009
Wideband Pulse Profiling
8510: vary delay of sampling pointPNA: trigger once at start of sweep
PW = 2 msPRF = 50 HzDuty cycle = 10%Points = 101IF BW = 35 kHz
Point sweep is turned off for wide-band pulse profiling
25Jan 2009
Data Acquisition for Pulse Profiling(Using Widest Bandwidths) – LB PNA-X
t
t
t
PNA(40
kHz)
PNA-L*(250 kHz)
PNA-L**(600 kHz)
* 2-port, 20, 40, 50 GHz** 2-port, 6, 13.5 GHz; 4-port, 20 GHz
Acquisition = 4 samples x 6 us/sample = 24 usTime per point = 24 us
Sample
Trace point
Acquisition = 4 samples x 1 us/sample = 4 usTime per point = 8 us
Acquisition = 47 samples x 25 ns/sample = 1.175 usTime per point = 2.35 us
26Jan 2009
Data Acquisition for Pulse Profiling – PNA-X(Using 5 MHz Bandwidth)
t
Acquisition = 16 samples x 16.7 ns/sample = 267 nsAcquisition overlap = 50%Time per point = 133 ns
27Jan 2009
Demo of Point-in-Pulse using Wideband Detection
PRF = 4 kHzWidth = 50 usPNA IF BW = 35 kHz
Note: Trace 2 has a narrower span and a more sensitive scale than Trace 1
CW response
Pulse response with improper delay
settings
28Jan 2009
Fastest PRI/PRF for Pulse-Pulse Measurements Using Wideband Detection
Conditions: point sweep; external trigger, CW sweep; IF autogain=off Maximum
IF bandwidthMinimum
PRIMaximum
PRFPNA models(20, 40, 50, 67 GHz) 40 kHz 170 us 5.9 kHz
PNA-L models(2-port, 20, 40, 50 GHz) 250 kHz 80 us 12.5 kHz
PNA-L models(2-port, 6, 13.5 GHz; 4-port, 20 GHz)
600 kHz 40 us 25 kHz
PNA-X models(26.5 GHz) 5 MHz 40 us 25 kHz
P1 P2 P3 P4 P5 P6 …
CW pulses
PRI
29Jan 2009
Agenda
• Pulsed-RF Overview• Pulsed-RF Measurement
Techniques• Wideband/Synchronous • Narrowband/Asynchronous
30Jan 2009
Pulsed Signal in Time and Frequency Domain
fc
Pulse repetition frequency(PRF = 1/PRI)
1/PW
Time domain
Pulse width (PW)
Pulse repetition period (PRP)Pulse repetition interval (PRI)
Carrier frequency (fc)
Measured S-parameters
Frequency domain
Duty cycle = on time/(on+off time)
= PW/PRI
31Jan 2009
)())()(()( 1 tshahtxtrecttyprfpw ∗⋅=
0 1/prf-1/prft
......*
∑nδ(t-n(1/prf))
0 1/prf 2/prf-1/prf-2/prf
......rectpw(t)
0 1/2pw-1/2pwt
x(t)
))(())()(()( sprfshahprfsXspwsincpwsY ⋅⋅⋅∗⋅⋅=
))(())(()( sprfshahprfspwsincpwsY ⋅⋅⋅⋅⋅=
)()()( sprfshahspwsincDutyCyclesY ⋅⋅⋅⋅=
Mathematical Representation of Pulsed Signal
32Jan 2009
Pulsed Frequency Domain Spectrum
This is the spectrum of a pulsed signal at a pulse repetition frequency of 1.69 kHzand a pulse width of 7 us.
Pulsed Spectrum
-60
-50
-40
-30
-20
-10
0-2
0000
00
-150
0000
-100
0000
-500
000 0
5000
00
1000
000
1500
000
2000
000
Frequency Offset (Hz)
Puls
ed R
epon
se (d
B)
Nulls at 1/pw
33Jan 2009
Pulsed Frequency Domain Spectrum(Zoom)
This is the same pulsed spectrum zoomed in on the fundamental frequency that is pulsed(center). Notice that the spectrum has components that are n*prf away from the fundamental. In pulse narrowband detection mode, ideally we would want a rectangular filter to filter out everything but the fundamental pulsed frequency.
Pulsed Spectrum(zoomed)
-0.0025
-0.002
-0.0015
-0.001
-0.0005
0
-200
0
-150
0
-100
0
-500 0
500
1000
1500
2000
Frequency Offset (Hz)
Puls
ed R
espo
nse
(dB
)
Wanted frequency component
First spectral tone at 1.69kHz=prf
34Jan 2009
Pulsed RF Spectrum (Zoomed In)
First spectral sideband at 1.7 kHz ( = PRF)
Ideal filter
Desired frequency component
Practical filters
3 dB bandwidth
Higher-selectivity (smaller shape factor) filter
35Jan 2009
Analog versus Digital Filtering
Classic analog variable-bandwidth bandpass filter:• Multiple-resonator synchronously tuned filter• Vary bandwidth by varying series resistances, vary shape factor by number of
resonators
Digital filtering: digital-signal processing after analog-to-digital conversion• Two filter types: finite impulse response (FIR) and infinite impulse response (IIR)• Vary bandwidth and shape factor by topology, number of delay elements, and
weighting factors
Anti-alias filter
ADC Digital-signal
processing
Z-1 Z-1x(n)
h(0) h(1) xx …+
36Jan 2009
Current PNA Pulse Detection Technique - Finite Impulse Response (FIR) Filter
Incoming sampled signal
Complex filtered output (e.g., S21)
t
M = number of filter sections (controls filter bandwidth)= minimum number of ADC samples required for one data point
h(n) = tap weightings (controls shape factor)
BW M BW M BW M40k 4 1.5k 101 30 480035k 5 1k 149 20 720030k 6 700 211 15 948020k 8 500 292 10 14,28015k 16 300 480 7 19,56010k 19 200 720 5 28,6807k 25 150 960 3 47,7605k 34 100 1440 2 71,6403k 53 70 2040 1.5 95,5202k 77 50 2880 1 143,280 PNA standard IF filters
t
Unit delay
Example FIR topology
Z-1 Z-1 Z-1 Z-1x(n)
x x
+
x
+
h(0) h(1) h(2) h(3)xx x
+
…
…
h(M-2) h(M-1)
y(M)M
Sample decimato
r++
As IF bandwidth gets narrower:• Number of sections (M) gets larger• More ADC samples needed per data point• Acquisition and processing time gets slower
37Jan 2009
Standard Filters and Corresponding Nulls• Nulling can be done with standard filters, but allowable PRFs are limited• PRF must be a harmonic of the frequency of first filter null• Difficult to null all undesirable spectral components• H08 allows “custom” IF BW’s, allowing full PRF flexibility and better rejection
BW (Hz) M First null
offset (Hz)BW (Hz) M First null
offset (Hz)
10k 19 24,813.90 100 1440 224.957k 25 16,977.93 70 2040 158.595k 34 11,520.74 50 2880 112.243k 53 6863.42 30 4800 67.292k 77 4543.39 20 7200 44.84
1.5k 101 3395.59 15 9480 34.051k 149 2255.81 10 14,280 22.60
700 211 1573.56 7 19,560 16.50500 292 1127.90 5 28,680 11.25300 480 680.55 3 47,760 6.76200 720 451.79 2 71,640 4.50150 960 338.13 1 143,280 2.25 -60
-50
-40
-30
-20
-10
0
Frequency Offset (Hz)
Filte
r Res
pons
e (d
B)
First nullPNA standard IF filters
2(# taps – 6) x sample-time
null spacing =
38Jan 2009
PNA IF Filters• We can take advantage of characteristics of PNA’s digital IF filters to
increase IF bandwidth for narrowband detection• Result is significantly faster measurement speeds
Frequency nulls exist at regular
spacing (determined by M)
log mag
lin mag
Apparent filter selectivity
39Jan 2009
-3 -2 -1 0 1 2 3
x 104
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Filtered Output Using Spectral Nulling
Pulsed spectrum Output
X
-3 -2 -1 0 1 2 3
x 104
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Digital filter (with nulls aligned with PRF)
• With “custom” filters, number of filter sections (M) can be chosen to align filter nulls with pulsed spectral components
• With spectral nulling, reject unwanted spectral components with much higher IF bandwidths compared to using standard IF filters
• Result: faster measurement speeds!
40Jan 2009
IF Bandwidth Comparison
With spectral nulling:IF BW = 415 Hz, sweep time = 1 sec
Without spectral nulling:IF BW = 30 Hz, sweep time = 14 sec
PRF = 2.349 kHzPW = 10 us (2.4% duty cycle)
41Jan 2009
Delta Bandwidth Comparison
IF bandwidth = 984 Hzsweep = 0.5 s
IF bandwidth = 95 Hzsweep = 3.3 s
Δnoise = 10*log[984/95] = 10.2 dB
42Jan 2009
Elimination of Additional Interfering Signals• Spectral nulling eliminates main pulse spectrum plus other undesired signals• Sources of spectral contamination:
• Spectral components can wrap around DC and fold back into pulse spectrum• Harmonics of "video feed-through" (leakage of baseband modulation signal)
due to RF modulator and IF gates• Receiver sensitive to 1st and 2nd LO images
DCfreq
Aliased spectral
componentsVideo
feedthrough
Main spectral components
43Jan 2009
Duty Cycle Effects with Narrowband Detection (DUT = HPF)
Pulse width = 3 μs (DC = 5.1%)
Pulse width = 1 μs (DC = 1.7%)
Pulse width = 100 ns (DC = 0.17%)
Pulse width = 100 nsDynamic range improved with averaging (101 avgs)
Note: this is frequency domain data, not a pulse profile
44Jan 2009
PNA-X Narrowband Detection Limits
Minimum Maximum PRI (PRF) 100 ms (10 Hz) 40 ns (25 MHz)Duty cycle .00003%* 90%
IF gate 33 ns**
* .00003% is the theoretical duty cycle limit, but this is probably not a practical value due to pulse desensitization. A more practical limit is probably .0001%
** Limited by internal pulse generators. With external pulse generator, minimum IF gate width is 20 ns
45Jan 2009
• 2- and 4-port versions • Built-in second source and internal combiner
for fast, convenient measurement setups• Flexibility and configurability• Internal modulators and pulse generators
for fast, simplified pulse measurements• High accuracy noise figure measurements
using Agilent’s unique source-correction method• Large touch screen display with intuitive user interface
Agilent’s N5242A premier performance microwave network analyzer offers the highest performance, plus:
PNA-X Offers Premier Network Analysis Performance
46Jan 2009
2-Port PNA-X Options 219, 224
Test port 1
R1
Source 1OUT 2
Source 2 (optional)
OUT 1 OUT 2
Test port 2
R2
35 dB65 dB 65 dB
Rear panel
A
35 dB
B
Source 2 Output 1
Source 2 Output 2
LO
To receivers
SW1 SW3 SW2
RF jumpers
J11 J10 J9 J8 J7 J2 J1
Pulse generators
OUT 1Pulse
modulator
Receivers
Pulsemodulator
12
34
Mechanical switch
47Jan 2009
4-Port PNA-X Options 419, 423
Test port 3
C
R3
Test port 1
R1
Source 1OUT 2
Source 2 (standard)
OUT 2
Test port 4
R4
Test port 2
R2
35 dB65 dB
35 dB65 dB 65 dB 35
dB65 dB
Rear panel
A
35 dB
D B
LO
To receivers
SW1 SW3 SW4 SW2
J11 J10 J9 J8 J7 J4 J3 J2 J1
RF jumpers
Pulse generators
Receivers
OUT 1Pulse
modulatorOUT 1
Pulsemodulator
12
34
Mechanical switch
48Jan 2009
PNA-X Rear Panel
Pwr I/OPwr I/O
Pulse I/OPulse I/O
2nd GPIB2nd GPIB
External IF inputsExternal IF inputs
Test Set I/OTest Set I/O
Handler I/OHandler I/O
Signal routing jumpers (go to mechanical switches)Signal routing jumpers (go to mechanical switches)
TriggeringTriggering
49Jan 2009
PNA-X Pulse HardwareThe customer can get access to the pulse hardware externally:
• The internal pulse modulator (s) can be pulsed externally• The 4 pulse generator outputs can be accessed externally• The internal narrowband IF receiver gates can be accessed
externally
Pin Name Description
1 IFGateAIn IF pulse gate input A (TTL)
2 IFGateBIn IF pulse gate input B (TTL)
3 IFGateCIn IF pulse gate input C (TTL)
4 IFGateDIn IF pulse gate input D (TTL)
5 IFGateRIn IF pulse gate input R (TTL)
6 DCOM ground
7 PulseSyncIn Pulse generator synchronization trigger input (TTL)
8 RFPulseModIn RF source pulse modulation drive input (TTL)
9 DCOM ground
10 Pulse1Out Programmable pulse train output #1 (TTL)
11 Pulse2Out Programmable pulse train output #2 (TTL)
12 Pulse3Out Programmable pulse train output #3 (TTL)
13 Pulse4Out Programmable pulse train output #4 (TTL)
14 n.c. no connect -- for future use
15 DCOM ground
N1966A
50Jan 2009
PNA-X Receiver Block Diagram
• Narrowband IF path for improved IMD and pulsed measurements• Internal IF gates for narrowband pulsed measurement• External IF inputs for antenna-system remote-mixing situations
IF gate
Anti-alias filter ADC
Digital FIR IF filter
Narrowband filter
External IF input
A
51Jan 2009
PNA-X Pulse Block Diagram• Internal Wideband and Narrowband Paths• Internal Pulse Generators• Internal Modulators• Programmable DSP
52Jan 2009
Product Features – Pulsed S-Parameters
Ease of Setup• Internal pulse modulators (one or two)• Internal pulse generators (four)• Very fast pulse-profile measurements
Wide- or narrow-band detection• Wideband down to 250 ns• Narrowband down to 20 ns
Dynamic range improvementsfor narrowband detection
• Crystal-filter path with increased gain• Patented software gating technique• Especially helpful for small duty cycles
8510
PNAPNA-X
Dyn
amic
Ran
ge (d
B)
100 10.0 1.0 0.1
100
80
60
40
20
0
WidebandDetection
8510Narrowband
Detection PNANarrowband
Detection 8510
0.01
Narrowband Detection PNA-X
Duty Cycle (%)
53Jan 2009
Agilent PNA-X Pulse Enhancements Detail
Key Pulse Features:• Internal Pulse Generators
• Up to 4 independent output channels that can be configured to drive internal components (modulators) or external components
• 60 MHz clock frequency(16.7 ns resolution)• Internal Pulse Modulators
• Can option with either 1 or 2 modulators• Pulse Width < 100 ns (PW spec = 33 ns;typical rise time < 5 ns)
• Time resolution on receive is less than 100 ns (spec = 33 ns) innarrowband mode
• Enhanced Narrowband Detection Technique• Substantial increase in measurement sensitivity and speed over
current narrowband technique based on new patented pulse receive architecture and algorithms
• Wideband detection technique current detection BW is 5 MHz (Current Time Resolution of 250 ns – FW upgrade)
New
New
New
54Jan 2009
New PNA-X Pulse Detection Techniques
The New PNA has added significant enhancements in the narrowbanddetection mode using the narrowband IF path:• Digital Filter Nulling
• The digital filter nulls can be placed precisely on the pulse spectral lines since their location is known when using the internal pulse generators
• Crystal Filter• There is a narrowband crystal filter (BW = 30 kHz) in the
narrowband pulse IF path which is used to increase the narrowband pulse mode sensitivity
• SW Gate• When using HW IF gating and internal pulse generation, we know
the on and off times of the gate (signal) precisely. Since the off times of the gate contain undesirable noise and/or residual gateisolation, the algorithm can improve the receiver sensitivity
55Jan 2009
PNA-X Pulse Receiver Algorithms – SW Gating
PNA-X also includes an enhanced software gating algorithm in pulse mode:
Since we know the gate timing exactly because of the utilization of the internal pulse generators we can remove residual noise and isolation from the measurement during the off times of the gate thus improving the measurement sensitivity. We basically replace the noise/isolation with an ideal ‘zero’ signal in the digital data.
56Jan 2009
PNA-X Pulse Profile with/without SW Gating (.001% Duty Cycle) Log Magnitude Pulse Profile
-200.00
-180.00
-160.00
-140.00
-120.00
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
0.00E+00 1.65E-05 3.30E-05 4.95E-05 6.60E-05 8.25E-05 9.90E-05 1.16E-04 1.32E-04
nanoseconds
dB
SW Gating
No SW Gating
57Jan 2009
PNA-X/PNA Dynamic Range Comparison
PNA / PNA-X Pulse Comparison (.001% Duty Cycle)
-120
-110-100
-90-80
-70-60
-50
-40-30
-20-10
0
7.74 8.24 8.74 9.24 9.74 10.24 10.74 11.24 11.74 12.24 12.74
Freq (GHz)
dB
PNA pulsePNA-X pulse (SW gate off)PNA-X pulsePNA-X CW
58Jan 2009
PNA-X Pulse Application – Main FormPNA-X option H08 provides a pulse application that is used to configure the PNA-X in narrowband pulse mode.
59Jan 2009
PNA-X Pulse Application – Pulse Generator/Modulator Configuration
Can specify the use of the internal or external pulse generators and modulators.
60Jan 2009
PNA-X Pulse Application – Pulse ProfileNew PNA-X solution is substantially faster due to:
- Virtually no communication overhead using internal pulse generators
-Increased measurement sensitivity allows use of wider IF BW’s
61Jan 2009
Z5623A Hxx RF Modulators• Z5623A H81 (2-20 GHz)
• The most common configuration• Contains pin switch, amplifier, directional coupler• Use jumpers to bypass internal amp or use high-power external amp
• Other quoted test sets:• Z5623A H832-20 GHz Bidirectional (two pin switches), no amplifier• Z5623A H842-40 GHz Bidirectional (two pin switches), no amplifier• Z5623A H86 2-40 GHz Unidirectional, no amplifier• Z5623A H872-50 GHz Bidirectional (two pin switches), no amplifier• Z5623A H90• etc
• Customization via Agilent’s “Specials” group:• Different frequency ranges • No amplifier or higher power amplifiers• High power components
Z5623A H81
62Jan 2009
Z5623A H83 RF Modulator 2-20 GHz
10/20/30
60 dB
10/20/30
60 dB ATN1 ATN2
CPLR1 CPLR2
16 dB 16 dB
SW8SW7
SourceIN
RCVRR1 IN
RCVRR2 IN
CPLRTHRU
CPLRTHRU
SourceIN
PulseOut
PulseOut
CPLRIN
AMPOUT
SourceOUT
AMPIN
Pulse 2IN
Pulse 1IN
CPLRIN
SourceOUT
AMPIN
AMPOUT
AMP 1TERM
AMP 1TERM
AMP 2TERM
AMP 2TERM
FilterIN
FilterIN
1 2
34SW1
1 2
34SW2
1 2
34SW3
12
3 4SW4
12
3 4SW5
12
3 4SW6
0
RCVR R1 OUT AMP IN
AMP OUTCPLR THRU
SOURCE IN
SOURCE OUT
CPLR IN
FILTER IN
PULSE OUT
PULSE 1IN
RCVR R2 OUTAMP IN
AMP OUT CPLR THRU
SOURCE IN
SOURCE OUT
CPLR IN
FILTER IN
PULSE OUT
PULSE 2IN
LINE
1
Z5623AH83 PULSE TEST SET, 1 GHz to 20 GHz
TTL 0,5 VDC, 10K OHM
PORT STATUS "GPIB ONLY"
AVOID STATIC DISCHARGE
CAUTION: SEE MANUAL FOR MAXiMUM POWER RATINGS CAUTION: SEE MANUAL FOR MAXiMUM POWER RATINGS
0
2
63Jan 2009
Pulse Generators• At least one pulse generator must have a 10 MHz
reference to lock to the PNA (master)• Remainder of pulse generators are triggered by master• Number of output modules depends on desired
measurements• Minimum number is 1 to control RF modulator• Other modules needed for point-in-pulse
measurements• IF gates can share a common output module
Required numberof output modules
Output module usage for independent gate control
Point-in-pulse measurements available
2 RF modulator; B gate S21 with ungated reference
3 RF modulator; A and B gates S11, S21 with ungated reference
3 RF modulator; R1 and B gates S21 with gated reference
4 RF modulator; R1, A and B gates S11, S21 with gated reference
5 RF modulators; R1, R2, A and B gates S11, S21, S12, S22 with gatedreferences
10 MHz
Trigger
64Jan 2009
Reference Signal Choices
CW stimulus Pulsed stimulus
Not gated
Gated
RF
Gate
RF
Gate
Any of these four signals can be used as a reference signal
1 2
43
65Jan 2009
Measuring Converters• Check “Converter Measurements”• Don’t use “Fixed PRF”• Measure average or point-in-pulse, but not pulse profile
DUT
66Jan 2009
Calibrating Your Pulsed-RF System
• Calibration is performed under pulsed conditions• Calibration methodology is identical to normal (swept sinusoid)
mode• ECal or mechanical standards can be used • In general, each unique set of pulse and gating conditions
requires a separate calibration
67Jan 2009
Summary
• Testing with pulsed-RF is very important for radar, EW, and wireless commssystems
• Narrowband detection:
• Spectral nulling technique improves measurement speed
• For radar and wireless comms applications, offers superior dynamic range/speed
• No lower limit to pulse widths
• Although the PNA uses different hardware and detection techniques than the 8510, measurement results are essentially the same!
• PNA also offers numerous platform benefits:
• Measurement flexibility (32 channels, 64 traces, 16 windows, 16,001 points)
• Connectivity (LAN, USB, …)
• Automation (open Windows®, COM, SCPI …)
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
7.74
7.99
8.24
8.49
8.74
8.99
9.24
9.49
9.74
9.99
10.2
4
10.4
9
10.7
4
10.9
9
11.2
4
11.4
9
11.7
4
11.9
9
12.2
4
12.4
9
12.7
4
Frequency (GHz)
S21
(dB
)
PNA8510
68Jan 2009
Resources• PNA Pulsed RF Configuration Guide (5988-9833EN)• App Note 1408-12: Accurate Pulsed Measurements (5989-4839EN)• www.netseminar.com: “Pulsed VNA Measurements: the Need to Null!”• www.agilent.com/find/pulsedrf