Dan Michaels email (remove spam text)
At 05:33 PM 1/21/01 -0000, you wrote:
>I think if you want to use low cost opamps you will have to cascade them.
>Otherwise I think you will need an opamp with an extraordinary
>gain-bandwidth figure (the frequency in the opamp data table) something
>close to 400MHz!
Yes, for typical opamp with 1mhz GBW [LM358, LM324], max gain usable
at 40khz is only about 1Mhz/40khz = 25, and you probably need gain
Might try LF353/TL082-84, with 4mhz GBW --> gain=100. Also, make
sure all cascaded stages are AC-coupled, including gnd leg gain
resistor, if single-ended supply being used:
| | +----+------.1uF-- (repeat 2x or 3x)
100K +-|- / |
| | | / |
| | |
Use another 100K resistor from "+" input to +Vcc, for single-ended
Lastly, play around a lot with ckt values.
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