Designing an amplifier circuit followed by a comparator

Thread Starter

Saswat Priyadarshi Nayak

Joined Apr 15, 2016
I have a signal output whose voltage ranges from 120uv to 15mv ...i need to set a reference point in between those voltages- (v) and V must be as closer to 120uv for minimizing error. the condition is i want to glow a led when voltage output is >V(ref voltage) and led in off state when voltage output < V.

to do so i thought of amplifying the signal to range of volts and then use a comparator to make the led on and off for those ranges. But it seems that the ompamp i was using ic-741 had an offset voltage of 10mv.. due to which the voltage output from the amplifier circuit saturated to Vcc(sat).


Joined Sep 13, 2015
To go to what low of a level, you likely will need to create a negative rail - even R2R opamps aren't going to work at 120uv.

I would use a dual opamp and one as amplifier and another as comparator.