OPA657 Photodiode Transconductance Amplifier problem

Muhammad Talha

Prodigy 45 points

Other Parts Discussed in Thread: OPA847

Hello All,

I am trying to simulate a circuit but somehow i am not getting the response that is supposed to come out.

I am attaching the circuit file herewith.

The frequency response of the circuit should be like this.

Instead I am getting a flat line.

I am new to high speed circuit design and simulation and can't work this out.

I would deeply appreciate any help.

Best Regards,

Muhammad Talha

OPA657_test_001.TSC

over 14 years ago

0 Muhammad Talha over 14 years ago

Prodigy 45 points

Sorry It is a Transimpedence Amplifier actually.

0 Bart Stiller over 14 years ago in reply to Muhammad Talha

TI__Expert 5400 points

Muhammad,

I noticed that the Fault condition of your current generator is set to "OFF", and this is causing the null response you are seeing. Changing this setting back to "None" should give you valid results.

More generally, for a low transimpedance gains(4.7kohm), the OPA847 is probably a better choice. I've attached an example circuit for reference. Let me know if you have any other questions --

1817.OPA847 TIA.TSC

0 Muhammad Talha over 14 years ago in reply to Bart Stiller

Prodigy 45 points

Hello Bart,

Thank you very much for the immediate reply.

My application is actually to build a optical receiver circuit for raw data rate of about 10 Mbps(or more).

Would you suggest that this is an optimal design for that?

Can the circuit be improved?

I am currently planning to use something like I am attaching right now.

I would highly appreciate if you could help.

Best Regards,

Muhammad Talha

upload_002.TSC

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OPA657 Photodiode Transconductance Amplifier problem