When I do my silulation in Cadence spectre, I input a sinewave into the filter block and test the THD of the output
I also tested the input and find that the input sinewave still got a THD of 100m. Why does the input also has such a high THD? Wouldn't it be ideal? Confusing~~~~~~
Length of simulation?
Time step?
Data range limit?
Education test: What is the spectrum of a sine wave that starts at t=0 ?:-)
...Jim Thompson
Long time ago I seem to recall a similar problem (or maybe the same problem) using the THD fct in spectre. I think what I did was:
1.subtract the DC component from the sine wave (or input wave)I just want to mention that the above stems from a long ago recollection. I may be completly off base ;-)/
-Roger
I input a 1V sinewave of 5KHz. I select from 5ms to 7.6ms(that is 13cycle) and the sample number is 5000. then I run the THD.
the spectrum of a 1V sinewave of 5K is only one spectrum of 1V at 5K
is that right? Looking forward to reply! Thank you
I have got no DC component. Maybe there is something wrong with the way I test.
But only if it lasts infinitely long. .. a minimum of theory is required .. .. lookup : me and the fourier transform ..
Rene
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