20MHz Transimpedance Photodiode Amplifier

Nov 09, 2015

The circuit below demonstrates a 20MHz BW transimpedance photodiode amplifier. An AD8065 65MHz op-amp is used for the transimpedance first stage followed by a voltage amplifier non-inverting gain stage using a 500MHz LT1222 op-amp with a gain of 20.6. The photodiode is a Vishay BPW24R with rise/fall times of 7ns or about 50MHz BW. The supply voltage is +/- 15V. The photodiode is reversed biased at -15V:

The optical impulse response (30ns wide IR LED pulse at λ=870nm) is shown below. A Digilent Analog Discovery scope with a -3dB BW of ~ 20MHz was used, demonstrating minimal pulse overshoot: