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https://designers-guide.org/forum/YaBB.pl Simulators >> Circuit Simulators >> Doubts on DFT of impulse response https://designers-guide.org/forum/YaBB.pl?num=1215088031 Message started by manodipan on Jul 3rd, 2008, 5:27am |
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Title: Doubts on DFT of impulse response Post by manodipan on Jul 3rd, 2008, 5:27am Hi friends, In switched capacitor circuits ,DFT of impulse response gives some idea about the frequency response.I have some doubt about the simulation that i have set up. My switched capacitor circuit works at 10MHz clock,the input impulse should be sampled once,so i have kept it on for 110ns>one clock cycle.Then i have got the output response run over let say 10us.Now i take DFT of output ,i have done DFT using rectangular window with 64 points over 10us.Now i have continuous time version of the circuit from which i have got capacitor values for SC circuit. Now in DFT of output i observe some lowering of gain at DC which is not proper. What sort of window,no. of points to be chosen for some frequency resolution??Thanks in advance... |
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Title: Re: Doubts on DFT of impulse response Post by pancho_hideboo on Jul 3rd, 2008, 5:47am manodipan wrote on Jul 3rd, 2008, 5:27am:
There are two isuues. (1) Difference of ideal impulse and actual impulse. Assuming DFT of finite width impulse, you have to consider difference between ideal impulse and actual impulse. (2) Output of SC filter is hold output even though an input to SC filter is ideal impulse. You have to compensate them. You can get same frequency response if you apply proper compensation. http://www.designers-guide.org/Forum/YaBB.pl?num=1210932698/1#1 |
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Title: Re: Doubts on DFT of impulse response Post by manodipan on Jul 4th, 2008, 12:42am Hi Paancho, What width of impulse is to be taken??can u refer some literature on compensating this hold output of SC filter?? |
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