Hello everyone,
I appreciate anyone looking at this at the moment. I need to design a multistage ampflifier circuit for a signal conditioning amplifier connected to a pressure transducer. Using op amps, my first stage has a gain of 5.556. Due to loading issues and ideal op amp properties this is as much gain as I can squeeze out of stage 1.
The problem is this. The whole system needs a variable gain from 44.444 to 88.888. (Due to transducer output span min and max datasheet values) My problem is for stage 2, using a POT and a fixed resistor, I cannot manage to accomplish this range.
For instance, if stage 1 is 5.556 to get a total gain of 40 stage 2 must be around 7 and to get a gain of 90ish Stage 2 would need a gain of around 18. The POT is limited from a fractional value of 0.4 to 0.6. And the minimum value of resistor to keep it "ideal" would be 10K and 10M. Due to the limitations on the POT I cannot find a fixed and variable resistor pair to get me a gain from 7-18 for stage 2.
I was hoping someone could lead me in the right direction in terms of fixing this problem or some considerations for me to take in.
Sincerely,
Ryan Kim.
I appreciate anyone looking at this at the moment. I need to design a multistage ampflifier circuit for a signal conditioning amplifier connected to a pressure transducer. Using op amps, my first stage has a gain of 5.556. Due to loading issues and ideal op amp properties this is as much gain as I can squeeze out of stage 1.
The problem is this. The whole system needs a variable gain from 44.444 to 88.888. (Due to transducer output span min and max datasheet values) My problem is for stage 2, using a POT and a fixed resistor, I cannot manage to accomplish this range.
For instance, if stage 1 is 5.556 to get a total gain of 40 stage 2 must be around 7 and to get a gain of 90ish Stage 2 would need a gain of around 18. The POT is limited from a fractional value of 0.4 to 0.6. And the minimum value of resistor to keep it "ideal" would be 10K and 10M. Due to the limitations on the POT I cannot find a fixed and variable resistor pair to get me a gain from 7-18 for stage 2.
I was hoping someone could lead me in the right direction in terms of fixing this problem or some considerations for me to take in.
Sincerely,
Ryan Kim.