Hello, i have already plotted FFT of output of ADC (attached picture 1) but that is after using filter function . i am using ADC architecture attached in the link
http://www.ntbaba.com/wenku/10/00000313.PDF

. there is filter (accumulator + counter). it is initialized before every conversion.
suppose y is filter output and xx(i) contains comparator outputs for n cycles

ADC function
inside adc function
[
for i = 1 to OSR
     input = amplitude* sin(2pi*f*i/OSR + phase)

do all ADC stuff
get integrator 2 output;
get comparator values in xx(i) for 128 cycles
end
y = 0;
for i = 1 to n
 y = y + xx(i);
end
output_ADC = y;

then i get an FFT in which noise bed is suppressed as shown in figure 1

Now i want to see noise spectrum also befoe applying filter. how can i check my output spectrum if i remove this filter function?

if i remove my filter functionality, I will just have compartor output values and output voltages of the integrators? how i see the spectrum of both signal and noise together as shown in fig 2 ?

i also face same problem :-|

singh did u find out?