Operation
56
© 2017 Pico Technology
pv106ug r1
6.9
Signal generator utility
This utility allows the instrument to act as a simple signal generator with variable output power. The VNA
measurement sweep must be stopped first and the control window, shown below, called from the
Utilities
menu:
The Signal Generator utility control window
6.10
Output power at the 1 dB gain compression point
utility
This utility allows the measurement of the power output at the 1 dB gain compression point (P
1dB
) of active
devices such as amplifiers. The measurement can be done at a single frequency or over the entire frequency
plan specified at the last S-parameter measurement calibration. Start the utility from the
Utilities
menu in
the main window.
P
1dB
calibration
Calibration minimizes errors by removing small variations associated with the instrument’s hardware. The
procedure is simple, as shown below.
Ensure that an S
21
(or S
11
+ S
21
, or 12-term) calibration has been carried out
Connect Port 1 to Port 2 as shown on the left-hand side of the figure below
Enter
Input Attenuation
and
Output Attenuation
values (or select
Read from file
)
Enter the test frequency (or select
Use sweep plan
) and click
Calibrate
P
1dB
test
The basic connection arrangement is shown on the right hand side of the figure below. Note that the input
and output attenuators should be carefully selected to ensure that the DUT compresses whilst preventing
the power at Port 2 of the instrument exceeding the nominal limit of +10 dBm. It is recommended that the
following guidelines are used to estimate the value of the input and output attenuators needed.
P
1dB(DUT)
– G
(DUT)
–1 + A
tt1
= –5 ± 2 dBm
P
1dB(DUT)
– A
tt2
+ 5 < 10 dBm
where:
P
1dB(DUT)
= output power of DUT at the 1 dB gain compression point
G
(DUT)
= linear gain of DUT
A
tt1
, A
tt2
= input and output attenuators
