Was the probe grounded using a spring clip off the probe tip, hitting the nearest ground that is tied directly to the 9572? If not, the waveform captured is not the waveform present during operation. Also, using a 10pF probe on a 2ns risetime signal is quite a heavy load / impedance mismatch. I've used 100:1 low capacitance probes (Zin = 5000 Ohms, Cin = 2pF or less) to mitigate that problem at less cost than a good FET probe. I also suspect the filter impedance is not constant versus frequency, leading to additional distortion of the square wave. Bob LaJeunesse
________________________________ From: beale <[email protected]> To: [email protected] Sent: Mon, December 12, 2011 1:29:24 PM Subject: [time-nuts] FE-5680A internal signal waveforms (60, 30, 10 MHz) ... A 200 MHz Rigol scope reads a risetime of 2 ns on CPLD pin 49, but the waveform looks so noisy and odd (see below), maybe I would be better off just squaring up the output sine. ...maybe if pin 49 was disconnected from the sine output filter, it would be more square (?) https://picasaweb.google.com/109928236040342205185/FE5680A#5685304143859526258 -John Beale _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
