Separating high pass and low pass TIA output bands.

Jul 11, 2017 43 Replies

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Phil Hobbs 9 years ago

That's 500:1, which is not horrible. What's the responsivity of the PD?

Assuming it's around 0.25 A/W, which is typical for silicon in the visible, that would be 2.5 uA to 1.25 mA. If you pick a 20k resistor, that gets you to the shot noise + 3 dB at the low end, and 25V at the high end, which you can do with a reasonably normal amplifier if you run it off asymmetric supplies like +28/-4.

At 40 MHz you'll probably need an AC tweak to keep the response flat, and that would differ between ranges.

If you do decide to use range switching, use a relay to switch the whole feedback resistor + AC tweak in and out.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net

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Artist 9 years ago

What low noise op amp has sufficient GBW and can operate off a 32V power supply difference?

By tweak do you referring to a subsequent stage that is a filter with a zero in it, or a multipole filter that has some overshoot at the high end of its frequency response?

The photodiode and its TIA is for a laser ultrasonics system's detection laser.

To respond to me directly remove sj. from the my email address's domain name. This is a spam jammer.

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