The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Mixed-Signal Design >> dynamic range of sigma delta adc design
https://designers-guide.org/forum/YaBB.pl?num=1222487300

Message started by min on Sep 26^th, 2008, 8:48pm

Title: dynamic range of sigma delta adc design
Post by min on Sep 26^th, 2008, 8:48pm

I can't understand the dynamic range of sigma delta

1. Does the dynamic range correlate with reference voltage?

2. what is the definition of full scale?

3. when first start design the sd adc how can I decide the full-scale

Title: Re: dynamic range of sigma delta adc design
Post by Berti on Sep 28^th, 2008, 11:53pm

Hi,

For your general understanding: A delta-sigma modulator is a feed-back system. For input signal larger than the max. feedback (reference voltage), the modulator can't be stable. This is your full-scale input, which depends directly on the reference voltage. Depending on the loop filter, the modulator turn instable already for smaller input signals (e.g. 0.5*vref).

The dynamic range is therefore given by a lower value (SNR=0dB) and full-scale (or where SNR becomes 0dB again due to instability).

Hope this helps!