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Design >> Mixed-Signal Design >> sigma delta ADC direct demodulation of 1-bit oversampled data
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Message started by aaron_do on Sep 14^th, 2009, 4:22am

Title: sigma delta ADC direct demodulation of 1-bit oversampled data
Post by aaron_do on Sep 14^th, 2009, 4:22am

Hi all,

suppose i have a sigma-delta ADC with a 1-bit quantizer. Assume I am using this ADC in an FSK receiver. Does anybody know if there has been any work done on directly demodulating the 1-bit oversampled output? In other words, can I avoid the decimation?

thanks,
Aaron

Title: Re: sigma delta ADC direct demodulation of 1-bit oversampled data
Post by vivkr on Sep 24^th, 2009, 2:06am

Hi Aaron,

I don't know of any papers on this specific topic. However, I would be concerned about using such a method since you will basically be sending over the wideband output of the modulator containing high-pass shaped noise. So you firstly need a lot of bandwidth, and secondly the channel nonidealities, specifically the finite bandwidth there and in the receiver will likely cause the shaped noise to fold back into the band. This is not considering other possible headaches that may face such as the backcoupling from your Tx to the delta-sigma modulator.

However, there is no other objection in principle. After all, the bitstream from a delta-sigma modulator is quite "random", similar to real communication channels. As long as you can send and detect with a sufficiently high BER, you should be OK.

Regards,

Vivek

Title: Re: sigma delta ADC direct demodulation of 1-bit oversampled data
Post by aaron_do on Sep 24^th, 2009, 5:01am

thanks. I'm trying to find the lowest power method of demodulating a signal coming out of a sigma delta ADC. I'm worried that a decimation filter will require high power consumption and will also leave the signal as a 10-bit signal which may be more complicated to demodulate than a 1-bit signal. Not really sure so i'll probably have to do more reading before I revisit this question...

Aaron