Agilent Technologies 45A, 46A, 54835A Select Vamptd from the Voltage submenu of the Measure menu

Chapter 3: Testing Performance

To test bandwidth

7Select Vamptd from the Voltage submenu of the Measure menu.

8Note the Vamptd (1) reading at the bottom of the screen. V10MHz =_______________mV.

9 Set the power meter Cal Factor % to the 10 MHz value from the calibration chart on the power sensor. Then press dB[REF] on the power meter to set a 0 dB reference.

This establishes the baseline output power at 10 MHz as a reference for the bandwidth measurement.

10Change the signal generator output frequency to 1000 MHz for Agilent 54835A,

1500 MHz for Agilent 54845A, or 2250 MHz for Agilent 54846A. Set the power meter chart Cal Factor % to the 2250 MHz value, to the 1500 MHz value, or to the 1000 MHz value depending on the model number.

This step compensates the power meter reading for changes in the power sensor output at 1000 MHz, 1500 MHz, or 2250 MHz with respect to 10 MHz.

11Adjust the signal generator output amplitude for a power reading as close as possible to 0.0 dB[REL]. Write down the actual reading. Reading = ______ dB [REL].

The reading on the power meter will be used to correct the final bandwidth value.

12Use one of the following steps depending on the Infiniium oscilloscope model being tested and the bandwidth acquisition mode:

a (Use this step for model 54835A 1000 MHz Equivalent Time bandwidth check.) Set the sweep speed to 500 ps/div using the Horizontal sweep speed knob.

b (Use this step for model 54845A 1500 MHz Equivalent Time bandwidth check.) Set the sweep speed to 50 ∝s/div using the Horizontal sweep speed knob.

c (Use this step for model 54846A 2250 MHz Equivalent Time bandwidth check.) Set the sweep speed to 50 ∝s/div using the Horizontal sweep speed knob.

d (Use this step for Real Time bandwidth checks: 1000 MHz on 54835A, 1500 MHz on 54845A, or 2250 MHz on 54836A)

Set the sweep speed to 500 ps/div using the Horizontal sweep speed knob. e (Use this step for 1 MΩ, 500 MHz bandwidth check for all three models.)

Set the sweep speed to 1 ns/div using the Horizontal sweep speed knob.

13Press the Clear Display key followed by the Run key to display a trace. (It there is no trace on the screen slowly adjust the Trigger Level knob through zero until a trace is

displayed.) Note the Vamptd(1) reading.

V2250MHz = _______________ mV (54846A) V1500MHz = _______________ mV (54845A) V1000MHz = _______________ mV (54835A)

14Calculate the response using the formula:

response(dB)	V1500 MHz		= 20log10
	= 20log10 --V-----	10-----MHz-----------		________=_______dB
For example:
487 mV
20log10 559-------------------mV	= 20log10 0.871 = –1.19dB

15Correct the result from step 14 with any difference in the power meter from step 11. Observe signs. For example:

Result from step 14 = -1.19 dB

Power meter reading = −0.5 dB(REL)

then true response = (−1.19)−(−0.5) = −0.69 dB (__________) − (__________) = _________dB

16The result from step 15 should be between +3.0 dB and −3.0 dB. Record the result in the Test Record.

17Switch the power splitter from the channel 1 to the channel 2 input.

18Turn off the current channel and turn on the next channel using the channel keys.

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