Hi all,
I'm looking at a basic photodiode-transimpedance circuit, which is measuring LED light modulated on/off by a 1kHz square wave.
I'm particularly interested in the waveform of the induced photocurrent, and subsequent output of the op-amp (Vo = Rf * Ipd). I've a photodiode with a particularly large junction capacitance (1200pF) - will this mean that the photocurrent will not have the same square wave form as the incoming signal, but rather be modified and look closer to a sine wave? I've done a bit of modelling in Spice but the photodiode models vary and I wanted to make sure I'm observing a real phenomena and not a non-physical solution that Spice sometimes spits out.
I know the output of the op-amp will be dependent on the it's bandwidth and the gain resistor and input capacitance (ie of the photodiode), but I'm particularly interested in what the actual process is that is modifying the form of the photocurrent?
Thanks in advance,
sdh
I'm looking at a basic photodiode-transimpedance circuit, which is measuring LED light modulated on/off by a 1kHz square wave.
I'm particularly interested in the waveform of the induced photocurrent, and subsequent output of the op-amp (Vo = Rf * Ipd). I've a photodiode with a particularly large junction capacitance (1200pF) - will this mean that the photocurrent will not have the same square wave form as the incoming signal, but rather be modified and look closer to a sine wave? I've done a bit of modelling in Spice but the photodiode models vary and I wanted to make sure I'm observing a real phenomena and not a non-physical solution that Spice sometimes spits out.
I know the output of the op-amp will be dependent on the it's bandwidth and the gain resistor and input capacitance (ie of the photodiode), but I'm particularly interested in what the actual process is that is modifying the form of the photocurrent?
Thanks in advance,
sdh