I am working on the design of 14 bits- 2nd order sigma delta ADC. I'm plotting the PSD using the spectrum assistant.
input signal 100nA ac with 200nA dc @ 1kHz
sampling frequency 1.6MHz
results plotted for 2^17 samples = 131072 samples
strobe period set to 625ns
simulation time = strobe period * no. of samples = 82ms
window hanning
There is a tone appears at around 12 Hz. It appears at the beginning of the plot. What can be the reason for this tone?
