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Berti

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Reference for I-/Q-channel ADC
Jul 01^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

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jbdavid

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Silicon Valley

Re: Reference for I-/Q-channel ADC
Reply #1 - 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

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jbdavid
Mixed Signal Design Verification

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Berti

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Re: Reference for I-/Q-channel ADC
Reply #2 - Jul 21^st, 2009, 11:02pm

Quote:

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..

:)

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

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wave3x

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Shang Hai, China.

Re: Reference for I-/Q-channel ADC
Reply #3 - 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:

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

Back to top

IP Logged