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Agilent
Combining Network and Spectrum
Analysis and IBASIC to Improve Device
Characterization and Test Time
Application Note 1288-1




Using the 4396B to analyze linear and
non-linear components - a 900 MHz AGC
amplifier example


Background

Active components require
linear and non-linear analysis
Active components (and now even
some passive components like crys-
tal filters) require analysis to charac-
terize linear parameters (gain/loss,
phase and group delay or S-parame-
ters) as well as non-linear perfor-
mance. Non-linear analysis is typi-
cally related to measuring signal dis-
tortion generated in the device such
as harmonic or inter-modulation dis-
tortion. Therefore, for complete
characterization, both a vector net-
work (VNA) and spectrum analyzer
(SA) are required, for linear and
non-linear evaluation respectively.

For example, to characterize an
amplifier for cellular applications,
we are typically interested in the fol-
lowing measurements. Note that 10
out of 12 measurements are made
with either a vector network ana-
lyzer (VNA) or spectrum analyzer
(SA).
Combining vector network analysis, spectrum analy-
sis, and a built-in controller in one instrument offers
new capabilities for RF testing.
Introduction
Today's RF designs are increasingly cost savings. But to fully character-
driven by time-to-market. At the ize RF components often requires
same time, advances in digital com- numerous test instruments and a
munication techniques are placing large investment of time and effort.
higher performance requirements on Automating testing to gather statisti-
components and subsystems. These cal information involves external
key driving forces require that com- computers and programming. In the
prehensive as well as time and cost past, this amount of work has been a
effective measurement techniques real obstacle to comprehensive char-
are used in design and manufactur- acterization. If operating data is
ing. In this note, test approaches needed for different or changing
using the combination of vector net- conditions, re-configuring the test
work, spectrum analysis and IBASIC station required a large commitment
program control are discussed show- of resources and long time delays
ing ways to get better device charac- before the data is available.
terization with faster results, higher
accuracy and increased test flexibil-
ity. Additional benefits include
Combining instrument func-
improved quality control data and tions for improved testing
ease of product transfer from design
to manufacturing. By combining vector-network and
spectrum analyses in the 4396B, and
by using the built-in IBASIC pro-
Characterization is impor- gramming capability, a powerful new
tant but difficult test tool is now available for lab or
manufacturing applications. As the
Accurate characterization if funda- core of a mini-ATE system, the
mental to both the designer and user 4396B can control and test multiple
of high-performance RF components. parameters with a single insertion of
Errors in operating parameter mea- the device-under-test (DUT). In addi-
surements or operating in untested tion, tests are easily changed or cus-
regions put the end product at risk. tomized for special operating condi-
Careful and complete characteriza- tions or one-of-a-kind test require-
tion pats benefits during the entire ments. The remainder of this note
product development cycle by allow- will use an amplifier test example to
ing better decisions in design and illustrate the principles and effec-
optimum testing during the manu- tiveness of this approach.
facturing phase, a large potential




Figure 1. 900 MHz AGC amplifier block diagram




2
Testing a silicon bipo-
lar MMIC 900 MHz
AGC amplifier for cel-
lular applications
In this example, a 900 MHz auto-
matic gain control (AGC) amplifier
was characterized using a 4396B-
controlled mini-ATE system.

The amplifier's block diagram is
shown in figure 1. A test board was
used (figure 2) for easy connection
using SMA 50 cables. The test sys-
tem consisted of an 4396B
network/spectrum analyzer, two pro-
Figure 3. Automated test system for component
grammable power supply voltage lev- characterization.
els, two programmable signal genera-
tors for inter-modulation distortion
(IMD) measurements and switch- Amplifier Measurement Results
controller with two RF switches. See (total measurement time = 9.2 seconds)
figure 3.
Parameter Symbol Value
Output power Pout 23.9 dBm
1 dB gain compression P1 dB 23.1 dBm
Power control range Pcr 69.2 dB
Small signal gain Gain 34.4 dB
3rd order intercept pt IP3 30.2 dBm
Input return loss IRL -20.3 dBm
Control current Icont 2.2 mA




Figure 2. Test board used for automated testing


Fast automated test results
The measurement parameters and
results from the AGC amplifier test
are shown below. The total time to
make these measurements using the
test system described was 9.2 sec-
onds. These results are in summary
form for easy review and compari-
son with other devices. A printout
was formulated using IBASIC pro-
gramming as a simple addition to
the automatic test control program.
(Printing out cursor values from the
various network and special data.)

To gain more insight into the mea-
surement techniques used, these
specific amplifier test are discussed
in more detail: