Keysight Technologies N9340B, User Manual

Page: 63 / 172

Making Measurements
Measuring Stop Band Attenuation of a Low-pass Filter
57
Measuring Stop Band Attenuation of a
Low-pass Filter
When measuring filter characteristics, it is useful to look
at the stimulus response over a wide frequency range.
Setting the analyzer x-axis (frequency) to display
logarithmically provides this function. The following
example uses the tracking generator to measure the
stop band attenuation of a 370 MHz low pass filter.
1 Connect the DUT as shown in
Figure 4-17 on page 41 .
This example uses a 370 MHz low pass filter.
2 Press [Preset] to perform a factory preset.
3 Set the start and stop frequencies:
• Press [FREQ] > {Start Freq} > 100 > {MHz}
• Press [FREQ] > {Stop Freq} > 1 > {GHz}
• Press [AMPTD] > {Scale Type} > {Log}
4 Press [BW/SWP] > 10 > {kHz} to set the resolution
bandwidth to 10 kHz.
5 Turn on the tracking generator and if necessary, set
the output power to -10 dBm:
Press [MODE] > {Track Generator} > {Amplitude (On)}
> –10 > {dBm}.
6 Press [BW/SWP] > {Sweep Time (Auto)} to put the
sweep time into stimulus response auto coupled
mode. Adjust the reference level if necessary to place
the signal on screen.
7 Connect the cable (but not the DUT) from the tracking
generator output to the analyzer input. Store the
frequency response into trace 4 and normalize:
Press [MEAS] > {Normalize} > {Store Ref} (1→4) >
{Normalize (On)}
CAU-
CAUTION
Excessive signal input may damage the DUT. Do not exceed
the maximum power that the device under test can tolerate.