vrl wrote on Jul 17th, 2008, 7:01pm:A CT sigma-delta modulator with RZ feedback, but same NTF as one with NRZ feedback, would have feedback pulses that are higher in amplitude in order to provide the same feedback information.
As a result, even in the case when the NRZ pattern is 1-0-1-0, the RZ case will suffer more from jitter due to the higher amplitude of the feedback pulses.
Pls correct me if I'm wrong.
Why would that be so? If we take a 1-bit DAC. Say the reference voltage is +1 V for quantizer output = +1 and -1 V for quantizer output = 0.
Now NRZ 1,0,1,0 gives +1,-1,+1,-1
RZ has +1, 0, -1, 0, +1, 0, -1, 0.
The RZ case has the same total transition step but the difference is that it first switches to 0 before going down to -1.
Regards
Vivek