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4.2.7
Squarewave Rise and Fall Times
Disconnect the distortion anlyzer and signal source from the filter.
Set the filter to the GAIN mode.
Set the filter input gain to 0dB and output gain to 6dB.
Set the filter input ohms to 50.
Set the filter coupling to AC.
Connect the input using a 50 ohm cable to the squarewave source set for 2Vp-p, 2.5MHz, squarewave.
Connect the filter output to an oscilloscope with a 50 ohm cable terminated at the scope end.
Observe on the scope that the overshoot and ringing is <5%.
Measure the rise and fall time from 10% and 90% waveform points.
should be <7ns.
Set the squarewave source for 0.2Vp-p.
Check the output waveform first with 20dB input gain and then 26dB output gain for <5% overshoot and
ringing, and <10ns rise and fall time.
4.2.8
Frequency Calibration
Set the filter for the initial settings at the beginning of this section.
Connect the filter input via a 50 ohm cable to a 1Vrms, 1kHz, sinewave signal source.
Connect the Fluke 8920a to the output of the filter with a 50 ohm cable.
Set the Fluke for relative dB operation.
Set the filter for a cutoff frequency of 1kHz and Gain mode.
Zero reference the Fluke.
Set the filter for Low-Pass mode (L.P.) and measure the drop in dB on the output.
Should be within -2.67dB to -3.37dB for a ±2% calibration range.
Set the sinewave generator and filter cutoff to the following frequencies and zero referencing the Fluke in
the filter gain mode.
Measure the drop in gain on the output of the filter when switching the filter to the Low-Pass mode.
Frequency
dB at
Cutoff Range
% Error Spec
1kHz
-2.67dB to -3.37dB
±2%
10kHz
100kHz
1MHz
10MHz
-2.21dB to -3.94dB
±5%
4.2.9
Wideband Noise
Set the filter for 25.6MHz, LP mode, 0dB input gain and 26dB output gain.
Disconnect the sinewave signal from the filter input.
With the Fluke connected to the output via a 50 ohm terminated cable, measure the wideband noise pres-
ent.
Wideband noise should be <5mV which translates into 500uV referenced to the input, since the net gain
from the filter input to the meter is 20dB.
Section 4 - Incoming Acceptance
4-7
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