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Measurements >> Other Measurements >> Dynamic dac measurements
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Message started by jdac_18 on Apr 23^rd, 2009, 4:09am

Title: Dynamic dac measurements
Post by jdac_18 on Apr 23^rd, 2009, 4:09am

I am testing a 10-bit segmented current steering dac, 4-binary, 6-thermometer. I have tested the Static parameters and get an INL of 0.5LSB and DNL 0.4LSB with no filter. Now I am testing the Dynamic parameters, and it seems pretty bad. The initial specs were for the dac to sample at 800Msps up to about 1/2 the nyquist. At 800Msps with a 10Mhz input sine, I can only an SFDR of 33dB. At higher input frequencies the SFDR goes down to below 10dB. I also checked the output on an oscillascope and starting from about 50Mhz the output is not a good sine wave, and by 200 it resembles a pulse. 10Mhz sine has quite a bit of glitch. Below is the screen shot.

Could it be a clock problem? Jitter, crosstalk?
Or a design flaw.

Equipment:
Agilent PPG
Osc
voltage generator

Title: Re: Dynamic dac measurements
Post by ywguo on Jun 7^th, 2009, 9:42pm

It looks like the design has some flaw. But what do you use to measure the dynamic performance?