sachinagg77
Member level 3
Dear Friends
I designed a SH circuit as first stage for my pipeline ADC. I use Cadence Analog Design environment and spectre for simulations.
I performed a DFT analysis on data obtained by transient analysis (coherant sampling, strobeperiod option used). The plot looks fine.
I also included the "fourier" component from the "analogLib" to get the THD results.
I noticed that as I reduce the number of sample points from 2048 to 256, the THD results gradually deteriote. To my surprise, the THD was positive for 256 points. Something seems to be wrong as the DFT plot still looks fine, though the noise floor goes up with decreased sample points.
Any advise would be appreciated.
With Regards
Sachin
I designed a SH circuit as first stage for my pipeline ADC. I use Cadence Analog Design environment and spectre for simulations.
I performed a DFT analysis on data obtained by transient analysis (coherant sampling, strobeperiod option used). The plot looks fine.
I also included the "fourier" component from the "analogLib" to get the THD results.
I noticed that as I reduce the number of sample points from 2048 to 256, the THD results gradually deteriote. To my surprise, the THD was positive for 256 points. Something seems to be wrong as the DFT plot still looks fine, though the noise floor goes up with decreased sample points.
Any advise would be appreciated.
With Regards
Sachin