High Speed Amplifier for Photodiode

Vijaya Kumar C

Other Parts Discussed in Thread: OPA380, LMH6629, OPA656, TLV3501

Can any one suggest me the best high speed amplifier IC for the photodiode application that work in noninverting mode also.

I am already using the OPA380. It working excellent, but in inverting mode&diode in Reverse bias.

I have connected the photodiode in Forward biased, in this case amplification is not happening.

I am sending the 30ns to 60ns pulses with photodiode(QSD2030F).

over 12 years ago

0 taylor Smith1 over 12 years ago

Prodigy 100 points

The OPA380 may be too slow for this 30ns pulse application. The slew rate is only 80V/us with 100ns settling time.

You need to find a trans impedance amp about 10x faster. The speed will be a function of you feedback impedance. If you try to use too high a feedback resistor, then the stray capacitance will limit the speed of the amplifier. TI has several design tools that will help you pick a better part. Typically, a cascade of a few amplifiers, each with lower gain will help you get the speed you need.

I would look for a 500MHz GBW, 500V/us slew rate and 10ns settling time amplifier.

0 Vijaya Kumar C over 12 years ago in reply to taylor Smith1

Prodigy 60 points

Thanks for your guidance in selecting the op-amps.

LMH6629 is having Bandwidth 900MHz, 1600V/us slew rate and 42ns settling time! is that what you are looking for.

0 taylor Smith1 over 12 years ago in reply to Vijaya Kumar C

Prodigy 100 points

I think you need a FET input like the OPA656. http://www.ti.com/docs/prod/folders/print/opa656.html

0 Vijaya Kumar C over 12 years ago in reply to taylor Smith1

Prodigy 60 points

But this is unity gain amplifier, it gives same output voltage level, it become problem for me since i fire laser on photodiode at 100 meters range, output pulses will be in <100mV. so i am looking for high gain amplifier at least 1.5V output. so that i can filter out with comparator(tlv3501)

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High Speed Amplifier for Photodiode