Re: CMOS analogues switch capacitance

Hello Joseph,


There is another issue with CMOS switches operating in low noise or high
speed applications. It is not really like capacitance but produces similar
effects, it is charge injection. Charge injection is relatively free of
temperature effects, but varies some with input voltage and supply voltage. Have you had to design to control it?


I guess anybody who ever designed samplers has. It's not always fun though, especially when you find out like I did a few years ago that your favorite quad array has been priced out of the typical BOM budget range :-(

However, there is another architecture that seems to not be taught anymore at the colleges: Four fast diodes and a toroid transformer. Ideally a quad but many of those have become expensive/unobtainium so I usually try to get away with pairs. That reduces Ci effects down to almost zilch.

--
Regards, Joerg

http://www.analogconsultants.com
.

Relevant Pages

  • Re: CMOS analogues switch capacitance
    ... effects, it is charge injection. ... but varies some with input voltage and supply voltage. ... I guess anybody who ever designed samplers has. ... your favorite quad array has been priced out of the typical BOM budget ...
    (sci.electronics.design)
  • Re: CMOS analogues switch capacitance
    ... effects, it is charge injection. ... I guess anybody who ever designed samplers has. ... especially when you find out like I did a few years ago that your favorite quad array has been priced out of the typical BOM budget range :-( ... there is another architecture that seems to not be taught anymore at the colleges: Four fast diodes and a toroid transformer. ...
    (sci.electronics.design)