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Is the SNR/DR spec reasonable? (Read 419 times)

xuedashun Junior Member Offline Posts: 18	Is the SNR/DR spec reasonable? Nov 20^th, 2009, 1:55pm In a class D amplifier 2 stage sigma delta modulator + driver + speaker the input is analog signal the spec is: SNR/DR min=85dB, -60dBFS From my understanding, it's impossible for 2stage SDM to reach 80dB SNR. If the SMD is used in classD, is the 85dB spec reasonable?, if reasonable, why?? Thanks.
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vivkr

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Re: Is the SNR/DR spec reasonable?
Reply #1 - Dec 11^th, 2009, 5:59am

xuedashun wrote on Nov 20^th, 2009, 1:55pm:

From my understanding, it's impossible for 2stage SDM to reach 80dB
SNR. If the SMD is used in classD, is the 85dB spec reasonable?, if
reasonable, why??

Thanks.

I think that would depend on the OSR. As a matter of fact, the first SDM I ever designed had an ideal SQNR of around 84 dB, and was second order if I recall correctly. Of course, the real SNR was a few dB lower as it was limited by thermal noise.

Regards,

Vivek

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