NF FRA5022, Instruction Manual

Page: 77 / 145

4.7 Equalizer
FRA5022
4-13
4.7 Equalizer
It is possible to use the data memory display setting A/B as an equalizer function to
compensate for the errors due to the measurement
’ s peripheral circuits.
Remove the SUT (system under test), connect directly the actual measurement terminal
and measure the peripheral circuit response, store the data in data memory B. When you
measure SUT again, the data is stored in A. When setting the data memory display to A/B
in the sweep menu screen, the vector ratio (magnitude ratio, phase difference) between A
and B is obtained as SUT characteristics by subtracting the characteristics of the
peripheral circuit from those of A.
(1) Measurement of peripheral circuit (2) Measurement of system under test
Figure 4-9 Connection with equalizer
The data memory display A/B displays the frequency range and frequency points of the
data memory A. In the frequency range where the data memory B has no data, no data is
displayed. When the values in data memory B are not matching those in data memory A
with respect to frequency, the value of data memory B at the corresponding frequency is
estimated by interpolating the values available in the vicinity of the relevant frequency
point. For easier understanding, it would be helpful to match the frequency range (upper
limit, lower limit) with the values at the frequency points obtained by performing
measurements on the peripheral circuit and the system under test.
The base data memory B should store clean data. Avoid using data with variance due to
noise, or data obtained by repeating UP/DOWN during sweep. Otherwise, the calculation
results of A/B may vary even if the data in the data memory A is consistent.
The analyzer input capacitance of
FRA5022
has a slight voltage dependency. For this
reason, equalizing may not be effective in reducing errors when the signal source
impedance or frequency is high.
CH1 CH2 OSC
FRA
Peripheral circuits
CH1 CH2 OSC
FRA
SUT
B A
（
OSC
：
OSCILLATOR
）