blacknight
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Is this a real ADC or are you just trying to simulate it?
In a real ADC, you will run into some problems if you try to overdrive the input.
First, if its an IC, you run the risk of oxide breakdown in some transistor in the worst case. If there are any ESD circuits present, then the voltage would be strapped to Vdd and what you apply to the ADC would not be the sine wave. Get an ADC that can support your input range, that would be your best shot. If not, and you are stuck with this one, then tie the -Vss of sine to gnd! of the ADC, then add a resistive divider and get the sine wave within range of the ADC. you will loose some SNR, but better than degrade SNDR. Or chopper it. Anything that works for a real circuit will work for a simulation as well.
Good luck!
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