I was wondering. Isn't there something wrong with the output pattern pictures of the Sigma Delta ADC ? The figures show the integrator ramping up and down a black line (Vin ?) at a constant slope but shouldn't it be ramping up and down around 0V with a different rising and falling slope acording to the input voltage ?

Thanks

 

Shouldn't the Vin signal go to the +ve not -ve pin of the opamp?

See ...

http://openbookproject.net/electricCircuits/Digital/DIGI_13.html#xtocid84848

 

I was wondering. Isn't there something wrong with the output pattern pictures of the Sigma Delta ADC ? The figures show the integrator ramping up and down a black line (Vin ?) at a constant slope but shouldn't it be ramping up and down around 0V with a different rising and falling slope acording to the input voltage ?

Thanks

If I overlay the integrator waveforms for all three figures, it is possible to see that the ramp slope increases slightly with a larger magnitude negative input voltage. See attached deltasigma.png image.

 

Shouldn't the Vin signal go to the +ve not -ve pin of the opamp?

See ...

http://openbookproject.net/electricCircuits/Digital/DIGI_13.html#xtocid84848

I think that either input will work, if we can find the circuit for a non-inverting integrator. I think that the + OP amp input would have a resistor in series between the input signal and the + OPA terminal and also a resistor from +OPA to ground. Although, I am not sure.