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



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



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



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


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


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)




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

pulsed-rf overview • pulsed-rf measurement techniques · • pulsed-rf overview • pulsed-rf...

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