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Design >> Mixed-Signal Design >> Switching arrangment in SC circuit
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Message started by tipu on Sep 25^th, 2008, 8:17am

Title: Switching arrangment in SC circuit
Post by tipu on Sep 25^th, 2008, 8:17am

Hello everyone!

I am working on a bandpass Sigma Delta converter. The circuit consists of a resonator having 2 integrators and an analog feedback path. I am having some difficulties while trying to adjust the switches in the feed back.

Like my both integrators are delaying integrators.They are sampled on phase '1' and in phase '2' the accumulated charge in phase '1' is transfered to the OTA.Same happens with the other integrator.

My question is which switching scheme should i use while modeling the feedback path from the output of the 2nd OTA to the input of the 1st OTA? IS it that i should sample the feedback input on the feedback capacitor during phase '2'?

Title: Re: Switching arrangment in SC circuit
Post by baohulu on Oct 6^th, 2008, 2:32am

hi, tupi
I think you choose the "forward Euler" structure, you may need to feedback you 2nd ota output to both inputs of 1st ota and 2nd ota at phase1 to sample and phase2 to integrate

there is a paper may can help you
"Switched-Capacitor Bandpass Delta-Sigma A/D Modulation at 10.7 MHz" JSSC, 1995, March