Making Measurements 3
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.
1Connect the DUT as shown in Figure 16. This example uses a 370 MHz low pass filter
2Press [Preset] to perform a factory preset.
3Set the start and stop frequencies:
•Press [FREQ] > {Start Freq} > 100 > {MHz}
•Press [FREQ] > {Stop Freq} > 1 > {GHz}
•Press [AMPTD] > {Scale Type} > {Log}
4Press [BW/SWP] > {RBW} > {10}> {kHz} to set the resolution bandwidth to 10 kHz.
| Excessive signal input may damage the DUT. Do not |
C ACUATUI O- N | |
| exceed the maximum power that the device under test can |
| tolerate. |
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5Turn on the tracking generator and if necessary, set the output power to - 10 dBm:
Press [Mode] > {Track Generator} > {Amplitude (On)} >
6Press [Sweep] > {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.
7Connect the cable (but not the DUT) from the tracking generator output to the analyzer input. Store the frequency response into trace 4 and normalize:
N9340A User’s Guide | 49 |
