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I am having a problem of designing pre-amplifier that responds to light pulses of 10 kHz. I have designed the one below but I don't understand the scenario in which the output voltage builds up to a very high level when the input pulses is about 1mV.

Schematics of my pre-amplifier

AndrejaKo
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Francis Ignas
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  • Have you calculated a gain for this? How and what is it? Try this: 1) Make C2 bigger to AC couple 10KHz. 2) Remove C1 to prevent integrating towards a power rail. 3) I would also put a resistor between C2 and the feedback node to set gain. 1K would give gain of 220. – C. Towne Springer Jan 07 '14 at 05:46
  • Make C2 much bigger - could not edit the comment after 5 min - leave C1 and use lower R1, like 22K. AD711 is an odd choice; Very fast precision op-amp with 16V/uS slew rate and recommended guarded inputs. Did you measure with a meter, or scope? Is it oscillating? – C. Towne Springer Jan 07 '14 at 06:00
  • Does 10KH mean 10KHz ? If so then please edit your post and type it properly. – alexan_e Jan 07 '14 at 08:50
  • @alexan_e: or better 10 kHz (there is no unit prefix capital K). – Curd Jan 07 '14 at 09:37
  • @Curd Agreed. - – alexan_e Jan 07 '14 at 09:40
  • Precisely what is the input that caused you to conclude that "the output voltage builds up to a very high level"? – Andy aka Jan 07 '14 at 11:20
  • Thanks for your advice,Thanks for your advice I have Impemented – Francis Ignas Jan 08 '14 at 15:10
  • also I Would like to help me on how to design a Single Delay line Pulse Shaping so tha I can judge the output voltage whether is high or low by amplitude based on the designed preamplifier – Francis Ignas Jan 08 '14 at 15:25

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