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Agilent
Network, Spectrum, and Impedance
Evaluation of Electronic Circuits and
Components
Application Note 1308-1
Agilent 4395A/Agilent 4396B
Network/Spectrum/Impedance
Analyzer
Introduction inductors, or other devices at the
With the current trends requiring actual working condition. An imped-
higher performance, smaller physical ance analyzer makes this task easy.
size, lower cost, and higher reliability,
fast cycle time is an increasingly After making a prototype, a review of
important part of the product design. the circuit operation requires meas-
This is true not only in the consumer urement of the following parameters:
industry, but also in the communica- harmonics, noise, transmission char-
tion and data processing industries. acteristics, and reflection characteris-
tics. The vector network analyzer, and
As shown in Figure 1, the develop- the spectrum analyzer must be used
ment procedure involves designing for making these measurements. The
the overall architecture, evaluating Agilent Technologies 4395A/4396B
electronic components, building pro- Network/Spectrum/Impedance
totypes, and evaluating circuit per- Analyzer Family combines three ana-
formance. From the design point of lyzer functions in one instrument.
view, it is essential to measure the This application note describes how
impedance characteristics of electron- the 4395A/96B can be used to contri-
ic components such as capacitors, bute fast cycle time for product
development.
Step1 Step2 Step3 Step4
Design Circuit Characterize Evaluate circuit
Make Circuit
Components perfomance
Inductor NA
Capacitor
Oscillator Circuit
Filter/ AMP SA
Circuit
Resonator Receiver
Transmitter
Figure 1. Circuit Development Process
2
The Agilent Combination nique (4395A: all RBWs, 4396B: 1Hz to
Analyzers have the following 3kHz RBW) breaks the speed barrier
to give you lower noise floors without
features sacrificing speed. In addition, low
Three analyzers in One box
phase noise provides improved signal
As the name implies, the Agilent
resolution. Option 1D6 (The Time-
4395A/4396B Network/Spectrum/
Gated Spectrum Analysis Function)
Impedance Analyzer Family can per-
performs accurate burst signal analy-
form vector network, spectrum, and
sis for burst-modulated signal evalua-
(optional) impedance measurements.
tion. As a spectrum analyzer, the 4395A
The combination analyzer family does
operates from 10 Hz to 500 MHz. The
not compromise vector network, spec-
4396B operates from 2 Hz to 1.8 GHz.
trum, or impedance performance. It
is a breakthrough in test instruments,
Impedance Analyzer Performance
giving you outstanding performance
When equipped with Option 010 and
as a full-capability combination ana-
the Agilent 43961A, Combination
lyzer. Precision measurements and
Analyzers can perform direct imped-
improved efficiency are possible with
ance measurements. Measurement
minimal training. Compared with
parameters such as Z , , C, L, Q, D,
using separate instruments, the
and more can be displayed directly
4395A/96B will save equipment cost
on the color display. A built-in lumped
and bench space.
equivalent circuit function aids cir-
cuit modeling and simulation. As an
Vector Network Analyzer Performance
Impedance Analyzer, the 4395A oper-
The Agilent Combination Analyzer
ates from 100 kHz to 500 MHz. The
Family offers you fast measurement
4396B operates from 100 kHz to 1.8 GHz.
with wide dynamic range. Transmis-
sion and reflection data can be pro-
Other Useful Functions
vided with an optional Reflection/
IBASIC, a subset of the HT BASIC
Transmission Test Set or optional
programming language, is included
S-Parameter Test Set. As a vector net-
with the standard 4395A/96B. IBASIC
work analyzer, the 4395A operates
is extremely powerful and easy to
from 10 Hz to 500 MHz. The 4396B
use. It can be used for automated
operates from 100 kHz to 1.8 GHz.
testing, analysis of measurement
results, or control of external equip-
Spectrum Analyzer Performance
ment via GPIB. Files such as instru-
The Agilent Combination Analyzers,
ment state files, TIFF files, and data
designed with new digital techniques,
files can be transferred via GPIB to
outperform the traditional analog
the controller/PC (host), which can
spectrum analyzer. Agilent's Combina-
easily manipulate the files. Usability
tion Analyzers feature a Fast Fourier
and productivity are improved through
Transform (FFT) digital-signal pro-
features such as the DOS supported
cessing (DSP) technique for 20 to 100
Floppy Disk Drive, the list sweep
times faster narrow-band spectrum
function, the marker function, and
measurement, when compared with
the limit line function.
swept-tuned spectrum analysis. The
Agilent analyzer's stepped FFT tech-
3
Table 1. Agilent 4395A Major Specification
Network Analyzer Specification Spectrum Analyzer Specification Impedance Analyzer Specification2
Frequency Range 10 Hz to 500 MHz1 Frequency Range
10 Hz to 500 MHz Frequency Range 100 kHz to 500 MHz
Frequency Resolution 1 mHz Noise Sidebands
<-104 dBc/Hz typical Meas. Parameter Z , z, R, X, Y , y,
at 10 kHz offset G, B, Cs, Cp, Ls, Lp, Rp,
Output Power Range -50 to 15 dBm Resolution Bandwidth 1 Hz to 1 MHz in Rs, X, D, Q, , x ,y
1-3-10 steps Z Accuracy 3 % (typical, basic accuracy)
Dynamic Range 115 dB@10 Hz IFBW Dynamic Range > 100 dB third-order Source Level -56 dBm to +9 dBm(at DUT)
free dynamic range DC Bias 40 V (20 mA(max))
Dynamic Accuracy 0.05 dB/0.3 deg. Level Accuracy 0.8 dB@50 MHz (Opt-001 DC source or
Calibration full two-port Sensitivity -145 dBm/Hz External DC source is
@freq. = 10 MHz required.)
Compensation open/short/load
Port Extension
Standard Features : Instrument BASIC, GPIB port, 3.5" floppy disk drive, direct print, RAM disk, VGA Monitor Output
Optional Features : Impedance measurement (Opt. 010), Time-Gated spectrum Analysis (Opt. 1D6),
High-Stability Frequency Reference (Opt. 1D5),
50 to 75 Spectrum Input Impedance Conversion (Opt. 1D7),
DC Source(> 40V, 100 mA (ALC)) (Opt. 001)
1. 100 kHz to 500 MHz if using the 87511A/B S-parameter test set.
2. With Option 010 and the 43961A RF impedance test kit.
Table 2. Agilent 4396B Major Specification
Network Analyzer Specification Spectrum Analyzer Specification Impedance Analyzer Specification 2
Frequency Range 100 kHz to 1.8 GHz 1 Frequency Range
2 Hz to 1.8 GHz Frequency Range 100 kHz to 1.8 GHz
Frequency Resolution 1 mHz Noise Sidebands
<-113 dBc/Hz typical Meas. Parameter Z , z, R, X, Y , y,
at 10 kHz offset G, B, Cs, Cp, Ls, Lp, Rp,
Output Power Range -60 to 20 dBm Resolution Bandwidth 1 Hz to 3 MHz in Rs, X, D, Q, , X, y
1-3-10 steps Meas. range 2 to 5 k
Dynamic Range >120 dB@10 Hz IFBW Dynamic Range > 100 dB third-order Z Accuracy 3% (typical, basic accuracy)
dynamic range Source Level -66 dBm to + 14 dBm
Dynamic Accuracy 0.05 dB/0.3 deg. Overall Level Accuracy < 1.0 dB (at DUT)
Calibration full two-port Sensitivity < -147 dBm/Hz DC Bias 40 V (20 mA(max))
@freq. = 1 GHz (External DC bias
source is required.)
Compensation open/short/load
Port Extension
Standard Features : Instrument BASIC, GPIB port, 3.5" floppy disk drive, direct print, RAM disk, VGA Monitor Output
Optional Features : Impedance measurement (Opt. 010), Time-Gated spectrum Analysis (Opt. 1D6),
High-Stability Frequency Reference (Opt. 1D5),
50 to 75 Spectrum Input Impedance Conversion (Opt. 1D7)
1. 300 kHz to 1.8 GHz if using the 85046A/B S-parameter test set.
2. With Option 010 and the 43961A RF impedance test kit.
4
Agilent Combination Analyzer Network Evaluation for Amplifier
Family Measurement Examples The measurement configuration for
The Combination Analyzer Family is network analysis of an amplifier is
a powerful tool for effective evalua- shown in Figure 3. Either an optional
tion of electronic circuit and device Reflection/Transmission test set or
performance. The following shows an optional S-parameter test set is
you some examples of measurements required to perform this analysis.
made by the combination analyzers.
Amplifier Evaluation
Amplifier characterization requires
the evaluation of a variety of meas- Agilent 4395A/96B Agilent 4395A/96B
urement parameters via vector net-
work analysis and spectrum analysis.
Figure 2 shows the major measure-
ment parameters for amplifier
evaluation.
Amplifier Evaluation
v SA
Noise
IMD
Harmonics Agilent 87512A R/T S-parameter
Spurious Test Set Test Set
SNR
NA Amplifier Amplifier
Gain under test under test
Phase
Group Delay (1) R/T Test Set is used (2) S-Parameter Test is used
Gain Compression
S11 & S22
Figure 3. Measurement Configuration for Amplifier Network Analysis.
Figure 2. Major Measurement Parameters
of Amplifier
Gain and Phase Measurement
The amplifier gain is defined as the
ratio of the amplifier output power
(delivered to a Z0 load) to the input
power (delivered from a Z0 source),
where (Z0) is the characteristic
impedance of the system. The Ampli-
fier gain is most commonly specified
as a typical or minimum value over
a specified frequency range, while
assuming that input and output sig-
nals are in the amplifier's linear oper-
ating range. Figure 4 shows the gain
and phase measurement result of an
amplifier.
Figure 4. Gain/Phase of the Amplifier
5
Gain Compression Measurement
The amplifier gain at a single fre-
quency is based on ideally linear per-
formance between the input power
and the output power. The real ampli-
fier gain is nonlinear. The output
power becomes saturated even if the
input power is increased. The most
common measurement of amplifier
compression is the 1-dB compression
point. This is defined as the input
power which results in a 1-dB decrease
in amplifier gain. The easiest way to
measure the 1-dB compression point
is to directly display normalized gain
(ratio between the reference channel
and the test channel).
Figure 5 shows the gain compression
measurement result (normalized gain).
The flat part of the trace is linear,
and the curved part (of the right side) Figure 5. Gain Compression of Amplifier
corresponds to compression caused
by higher input power. The Agilent The input and output in a high fre- When the input and the output are
Combination Analyzers have the quency circuit are matched with a perfectly matched, there is no reflec-
ability to do power sweeps where the characteristic impedance, which may tion, which means R1 is minus infinity.
maximum range is 20 dB. The marker drift from the ideal characteristic Figure 6 shows the return loss meas-
function can easily indicate the 1-dB impedance depending on frequency. urement result example for an amplifier.
decrease point. These functions help This change in characteristic imped-
you to easily evaluate the gain com- ance will cause reflections. The indi- In case of using the S-parameter test
pression of the amplifier. cated reflection parameters are the set with the instrument, you can per-
reflection coefficient (Gamma (S11 or form the full two-port calibration to
Return Loss (S11, S22) Measurement S22)) and return loss(Rl). The return obtain the best accuracy for the input
When S11, S22, or Return loss are loss is calculated by using the follow- or output impedance and the other
measured, either the Reflection/ ing formula. evaluations.
Transmission Test Set or the S-Para-
meter test set is required (as shown Rl = -20 xlog(S11) or -20 xlog(S22)
in Figure 3).
Figure 6. Return Loss Measurement Example
6
Spectrum Evaluation for Amplifier
Harmonic Distortion Measurement Agilent 4395A/96B
Nonlinear behaviors in the amplifier
will cause harmonics of the input
signal to appear at the output along
with the fundamental. These harm-
onics are integer multiples of the
input (fundamental) frequency, and
are usually specified in terms of dB
below the fundamental signal for a
given input level (commonly expressed
To: Spectrum Port
as dBc). The measurement configura-
tion for the harmonic distortion is
shown in Figure 7.
The 4395A/96B has a multiple marker
function. This function can easily
Signal Generator Amplifier
indicate all of the harmonic distortion
under test
points. Figure 8 shows the measure-
ment example for harmonic distor-
tion of an amplifier.
Figure 7. Measurement Configuration for Harmonic Distortion
Figure 8. Harmonic Distortion Measurement
7
Intermodulation Distortion Measurement
Another nonlinear behavior in ampli- Agilent 4395A/96B
fiers is intermodulation distortion.
When two input signals are applied to
a nonlinear amplifier, the output con-
tains additional frequency compo-
nents. These additional components
are the intermodulation distortion
products. As products of a two-tone
example, the output signal will con- Signal Generator To Spectrum Port
tain frequency components at the two
fundamental input frequencies [f1 and f2];
harmonics will be seen at [2 xf1, 2 xf2, Combiner
3 xf1, and 3 xf2]; second-order prod-
ucts at [f1+f2 and f1-f2]; and third
order products at [2 xf1-f2 and 2 xf2-f1]. Amplifier
The third order products are very Signal Generator under test
close to the fundamentals and typi-
cally fall within the bandwidth of the
amplifier. To measure intermodula-
tion distortion, two signal generators
Figure 9. Measurement Configuration of the Intermodulation Distortion
are required. The signal generators
outputs are connected together
through a coupler or combiner. This
device must ensure sufficient isola-
tion between the two RF sources so
that no intermodulation occurs in
their output stages. The measurement
configuration is shown in Figure 9.
The Agilent 4395A/96B, using the list
sweep function, allows you to break
the span into segments with variable
numbers of points and RBW's. This
optimizes the sweep speed for proper
dynamic range, and enables you to
look at both the two tone signals
and the intermodulation distortions.
Figure 10 shows the measurement
results by using the list sweep function.
Segment #1 Segment #2 Segment #3
Center Freq.=99.9MHz Center Freq.=100.05MHz Center Freq.=100.2MHz
Span Freq.=20kHz Span Freq.=200kHz Span Freq.=20kHz
RBW=30Hz RBW=1kHz RBW=30Hz
Figure 10. Measurement Results of Intermodulation Distortion by Using List Sweep
Function
8
Noise Figure (NF) Measurement Filter Evaluation
Noise Figure (NF) expresses the de- Filters are generally passive, linear,
gree of noise generated in an amplifier. two-port devices that, most often,
The NF value for an ideal amplifier, can be completely characterized using
with zero internal noise, is 1 (=0dB). swept frequency transmission/reflec-
The NF value for an amplifier is tion techniques, and sometimes spec-
determined with the following formula. trum technique.
Cin/Nin Cin/kTB Nout
NF = = = Figure 11 shows the major measure-
Cout/Nout CinG/Nout GKTB
ment parameters for filter (especially
IF SAW filter) evaluation.
Where,
Cin = Input Signal Power [W]
Nin = Noise Signal Power [W]
Cout = Output Signal Power [W]
Nout = Output Noise Power [W] IF SAW Filter Evaluation
K = Bolzmann's constant =
1.381 x 10-23 (J/