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https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> Need help in designing an opamp circuit https://designers-guide.org/forum/YaBB.pl?num=1067435667 Message started by pt3rg on Oct 29th, 2003, 5:54am |
Title: Need help in designing an opamp circuit Post by pt3rg on Oct 29th, 2003, 5:54am I need help in designing an opamp circuit with the following features: A difference of 45.9mV for the Vin will result in a 0.1V difference for the Vout. For example, if Vin=4.1V and Vout =5V a change in Vin = 4.05V will make Vout = 4.9V It doesn't matter what are the values of Vin and Vout, it's the difference that's important. |
Title: Re: Need help in designing an opamp circuit Post by Paul on Oct 30th, 2003, 1:06am If I understand correctly, you want to track changes of Vin over time. You could do this using a switched-capacitor structure calculating Vin(k)-Vin(k-1) and amplifying this difference. Is discrete-time operation acceptable for your application? Generally speaking, a high-pass topology would reject the DC component of your input and amplify the high-frequency components. Paul |
Title: Re: Need help in designing an opamp circuit Post by Ken Kundert on Oct 30th, 2003, 9:51am The way I understand his post is that he wants a unity gain amplifier with a built-in 100mV offset. To do so, you could configure a unity gain amplifier that has a resistor in the feedback, then build a current source that pulls a fixed current through that resistor. In that way, the feedback voltage will always be offset from the output voltage by a fixed amount, and so the output would have a fixed offset from the input. -Ken |
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