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Design >> Mixed-Signal Design >> Reference for I-/Q-channel ADC
https://designers-guide.org/forum/YaBB.pl?num=1246458047

Message started by Berti on Jul 1^st, 2009, 7:20am

Title: Reference for I-/Q-channel ADC
Post by Berti on Jul 1^st, 2009, 7:20am

Hi all,

I have two (I- and Q-channel) delta-sigma ADCs for cellular, each with his own reference voltage buffer. I am wondering whether it makes sense to share the buffer (thereby minimizing mismatch on the voltage reference which increases image rejection etc.) or is this a bad idea because of cross-talk between the two channels?

Regards

Title: Re: Reference for I-/Q-channel ADC
Post by jbdavid on Jul 16^th, 2009, 6:09pm

If I were a design lead, I wouldn't accept your decision based just on an answer from this forum.. I'd spend an hour with you just reviewing how you modeled the potential interaction, and looking over the simulation results on which you based your decision..

Its the kind of thing good designers write papers about..
jbd

Title: Re: Reference for I-/Q-channel ADC
Post by Berti on Jul 21^st, 2009, 11:02pm

Quote:

:)

I agree, but it is always good to collect some other opinions ....

Title: Re: Reference for I-/Q-channel ADC
Post by wave3x on Aug 18^th, 2009, 11:14pm

I think IQ ADC need not to use independent reference driver, just to simplify the design and layout. Cross-talk will not be a big issue. image rejection also be a less significant issue just if you pain a little attention about it. Of course I assume your system does not need a IR < -50dB.

Berti wrote on Jul 1^st, 2009, 7:20am: