Help with current amplification

[ShreyasPradhan]

I am fairly new to electronics. I am working on a project relating to Avalanche Photo Diode(APD) measurements. I have connected the APD in the reverse bias mode with 100V DC. I am getting a low current out of it; hence i wish to amplify the same. For the current amplification i am using 2222n transistors in darlington pair mode. Please help me out with the connections. Where should i connect the anode and the cathode, and where to take the output from? Thanks in advance.

 

[jayanth.devarayanadurga]

If the current is in uA or nA range then use an OpAmp to amplify it.

 

[keith1200rs]

You should be looking at transimpedance amplifiers, not discrete circuits with switching transistors.

You need to ensure you protect against high voltages blowing up your amplifier.

APDs are run close to breakdown. While for experimentation purposes you can set the voltage manually, a full design requires some means of adjusting to compensate for the high temperature coefficient of the breakdown voltage.

Make sure you limit the current from your high voltage power supply to the APD to a level that the APD can withstand. That only needs to be a resistor.

Keith

 

[ShreyasPradhan]

Thanks a lot! I will try with a transimpedance amplifier.