PhotoDiode Amplifier with Op Amp and MOSFET Explained

An example of PhotoDiode Amplifier designed with Op Amp, P-channel MOSFET transistor, Zener Diode and potentiometer is explained in this analog circuit video. Photodiode receives and converts the optical signal into small electric reverse bias current on the order of 10s of nano Amp up to few 100 micro Amp. The amplifier on one side provides this reverse bias current to the photodiode and also generates and amplified and inverted copy of that current as its output source current. Few choices of enhancement mode PMOS Transistors from Microchip Corp., Rohm and Vishay Semiconductor are presented as well.

[@STEMprof]

Thanks for watching. For more analog circuit videos see:
PhotoDiode Amplifier with Data Compression Explained ruclips.net/video/hqrRx2ufAwg/видео.html
Amplifier with -25 to 55 dB Attenuation-Gain range ruclips.net/video/oyz6lTGd2Xo/видео.html
Thermometer Circuit Design with Op Amp & BJT transistor ruclips.net/video/55YsraFE0rg/видео.html
Electronic Gain Control for Op Amp Amplifier ruclips.net/video/NoNgQpbj77Y/видео.html
Instrumentation Amplifier with Electronic Gain Control ruclips.net/video/C4tghZ-q6Zs/видео.html
Power Amplifier Design (Class A) with Transformer ruclips.net/video/gKlJrqGqeCI/видео.html
VCA Electronic Gain Control (Part 1): Voltage-Controlled Attenuator Overview ruclips.net/video/cFzYZsPEtP0/видео.html
Analog Multiplier Circuit ruclips.net/video/VP53A2zpVMQ/видео.html
Push-Pull Power Amplifier Design with Op Amp, Sziklai Darlington Transistors ruclips.net/video/8BFzsi7-Vbs/видео.html
Analog Vector Summer Circuit Design with Op Amp and BJT Transistors ruclips.net/video/PIAsa0QNVns/видео.html
Op Amp Analog Computer Differential Equation Solver ruclips.net/video/ENq39EesfPw/видео.html
Push-Pull Power Amplifier with Darlington Transistors ruclips.net/video/866MYibo8yE/видео.html
Sallen-Key Analog Filter Design Tutorial ruclips.net/video/KwUnQXbk7gM/видео.html
And the Analog Circuits Video playlist: ruclips.net/p/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt I hope these Circuit design and analysis videos are interesting.

[@erikev]

Thanks for great videos. Photodiode receivers often have to operate at high frequencies, often many GHz. How can you compensate for the capacitance of the photodiode witch become significant at high frequencies even below 1 pF. Also, since the signal is an RF signal, can you make a diagram using current feedback and an output with z=50Ω. Could you recommend components?

[@STEMprof]

You are welcome. Glad that you liked this video. The photodiode amplifier presented here is not suitable for Giga Hertz communications. The fastest commercially available Op Amps have gain-bandwidth product (GBW) of 8 to 10 GHz enabling them to operate in closed-loop feedback on signals up to few hundred MHz modulated on optical career that is received by the photodiode. I hope this is helpful.

[@spicken]

Nice, any suggestions for a phototransistor as the detector?

[@STEMprof]

Thank you! Depends on your target application and specific wavelength. But generally speaking MTD8600N4 is an NPN phototransistor with peak photo response at 880 nm and spectral sensitivity of visible to near Infrared (400 to 1100 nm). To see a large selection of phototransistors pls also check www.vishay.com/en/photo-detectors/phototransistor/ and www.digikey.com/en/products/filter/phototransistors/544 . More amplifier examples are in my analog circuits Playlist ruclips.net/p/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt . I hope this is helpful.

[@spicken]

@STEMprof thank you, certainly a large list of interesting circuits & analysis you provide.

[@STEMprof]

You are welcome.

[@johnford7847]

Thank you.

[@STEMprof]

You are welcome. More circuit examples are in my Analog Design Videos Playlist ruclips.net/p/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt

[@t7732155980]

You will not be able to use this circuit for high current (you mentioned 1A at time 13:00) , since the first op-amp is the one that drives the current.

[@STEMprof]

Thank you for your interest in this circuit and for sharing your thoughts. You have a good point that for high-current scenarios extra care is needed. Either the first Op Amp output needs to be able to handle the target current or an easy mod would be the first Op Amp driving the base of a high-current BJT transistor whose emitter is driving the common node of R2 and R3 resistors. Thanks again :)

[@SergiuCosminViorel]

i like negative, not positive

[@brucesmith9144]

Are you positive about that? 😉

[@STEMprof]

😄🙋‍♂️

[@AllenSA_Lymangirl]

👍