Berti wrote on Feb 16th, 2009, 8:35am:Hi Neoflash,
It doesn't matter in which phase you refresh the CMFB. But usually it is done during the sampling phase in order to balance the capacitive load of the amplifier.
I am not sure if I understand that right, but to my understanding is the speed (bandwidth) of the SC-CMFB independent of the clock frequency.
Regards
I did an experiment and find that if I do CMFB refresh in sampling phase, then in integrating phase the output Common mode voltage is not well regulated.
Instead, the CM voltage during sampling phase is very well controlled. However, I don't think the CM voltage in sampling phase is important. At this phase, OPAMP is not supposed to process signal.
I prefered to do the CMFB cap refreshing at integration phase, and let output CM in integration phase to be regulated. Right?