I am working on current to frequency converter which consists of following two circuits

1- Integrator circuit which integrates the current. In the beginning output of this stage is RESET to ground (0V) and then because of current integration, output of integrator starts rising.

2- Output of integrator goes to a comparator which compares this voltage with a reference voltage and as soon as output of integrator becomes equal to this reference, comparator output toggles and RESET the integrator.

What I see is very high level of noise at low frequencies. Can someone please suggest some reference for understanding the root cause of this type of noise better.

Any suggestion/comment with be very useful.

Thanks,
Raj

IF the input current noise is white, after integration will have 1/f^2 profile and therefore more noise power at lower frequency.
This is normal for any integrator processing white noise at its input....

Tosei