Bandwidth calculation of transimpedence amplifier(on common source stage)
Hello,
I want an equation to calculate the bandwidth/3db frequency of the circuit which is basically a transimpedence amplifier. Both the transistors are in saturation region.
Can you please help me out with some hints.
Thanks in advance.
But you asked for bandwidth.... the feedback resistor will influence the bandwidth.
I may be wrong, but I think you can´t omit it for bandwidth calculations.
Re: Bandwidth calculation of transimpedence amplifier(on common source stage)
Hello,
You're absolutely right. I need to calculate the bandwidth with and without the feedback resistor. So if I can find anyone of those I can do other one.
Thanks in advance.
Re: Bandwidth calculation of transimpedence amplifier(on common source stage)
Sketch an equivalent circuit of the post #1 schematic. You'll see an input and output pole if Cdg is small. Cdg however acts as Miller capacitor and performs pole splitting. Derivation in profound analog design text books, e.g. Gray/Hurst/Lewis/Meyer.
Re: Bandwidth calculation of transimpedence amplifier(on common source stage)
Thanks FvM for your reply.
In my case both Cgd & Cgs are around 3fF which is quite small. And input frequency is just 1hz. So do I need to consider this capacitance.
Thanks in advance.