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Making Measurements 3

N9340A User’s Guide 49

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 16. 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] > {RBW} > {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 [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.

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:

CAU-CAUTION

Excessive signal input may damage the DUT. Do not

exceed the maximum power that the device under test can

tolerate.

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Agilent Technologies N9340A Manuale Utente Pagina 59