How to simulate a adc,such as a sigma-delta?

[xdy83]

In the circuit simulation, input a sin wave and calculate the snr of the output.But this snr must be ideal, that is SQNR. How to get the real SNR of a adc?
Does it need to add a noise in the input or on the supply?and how ?
For a sigma-delta adc, how to get the DR? Except the snr and dr, what else would be simulated?

thanks

 

[qslazio]

It's hard to include random noise in SPICE simulation.
But you can try verilog-a/ams for evaluating their impact on ADC performance.

 

[fatcat1205]

usually we calculate the KT/C noise and some other noise of Opamp manually, then add it to the SQNR to get the SNR.
Yes, you can add some verilog-a noise source at the input, but the value of this noise is still calculated manually. So it may not similar to the real chip test. Besides this, KT/C noise is usually much larger than the quantization noise, so if add KT/C noise, you will not see the noise shaping in the low frequency, this is not good for you to estimate the performance of the ADC.


I have write some verilog-a code to generate the white noise in transient analysis. But I have not added this noise source into my ADC design.I hope, it may help you somehow.

 

[xdy83]

when simulating in Simulink,i had considered the kt/c noise and other noise. but in the circuit simulation, how can i get the real snr? need to add some noise on the sinusoidal input ?