S/H frequency response...

[gggould]

Hi all,

I have a question about the sample and hold output frequency response:

If we pass a 0dbm 3MHz sin wave to 100MHz S/H block, is the output spectrum going to be

1. (all tones at 3MHz +- N*100MHz with 0dbm mag) * sinc_response_center_at_DC

or

2. (all tones at 3MHz +- N*100MHz with 0dbm mag) * sinc_response_center_at_DC + (all tones at 3MHz +- N*100MHz with 0dbm mag) * sinc_response_center_at_100MHz + (all tones at 3MHz +- N*100MHz with 0dbm mag) * sinc_response_center_at_200MHz .....


In other word, when we sample/interpolate/decimate a signal, does the transfer function get replicated as well?

Thanks

 

[bulx]

A sample and hold operation can be seen as continuous-time (analog) filter , and has a low pass response. It has a sinc shaped response, it doesnt cause any images to be created, like any other continuous operation.

Decimation and interpolation are different, images are required to be handled properly.
- b