Spectrum analysis of DC signals

[sameenminto]

Hi All,

I am designing a wheatstone bridge CMOS temperature sensor in Cadence.
Now since it is a resistive sensor, my input in DC.
How to do the spectrum analysis for DC signals?
I have heard of dithering but not sure how to apply it here.
Thanks and regards.

Sameen

 

[AMS012]

For characterizing the circuit, you can assume that the input (temp) is varying slowly (indeed the temperature will be varying). You can use very slow sinusoid to characterize, say 100Hz or so.

 

[sameenminto]

For characterizing the circuit, you can assume that the input (temp) is varying slowly (indeed the temperature will be varying). You can use very slow sinusoid to characterize, say 100Hz or so.

Thank you for your response.
So lets say the differential output from my bridge is 100mV @ 32 degrees. Shall I test the ADC by giving it a sine input of 100Hz with 50mV amplitude centered around Vcm?

 

[AMS012]

Thank you for your response.
So lets say the differential output from my bridge is 100mV @ 32 degrees. Shall I test the ADC by giving it a sine input of 100Hz with 50mV amplitude centered around Vcm?

Yes, that should give a very good idea of to what accuracy you will be able to measure the temperature. The thing to ensure is that with the sinusoid input, the harmonic distortions are well below the quantization noise floor which means that your temp accuracy is only limited by the ADC SQNR.