What simulations do I need to perform to analyze the working of my transimpedance amplifier?

[VisheshG24]

Hi,
I am trying to understand the working of the trans-impedance amplifier. What simulations does people generally perform to see, say the transimpedance gain. How to find the transimpedance gain from the simulations. How to get the bandwidth of working of my transimpedance amplifier? What are the other things I need to simulate to prove that it is a good transimpedance amplifier.

 

[Dominik Przyborowski]

Input: current
Output: voltage
Use AC simulations with ac current set to 1 and look on the output.
"Good" result: dc transimpedance gain is equal to feedback resistor; input impedance is low for desired bandwidth, noises are coming from input device as major source (in 50%).

 

[VisheshG24]

Hi Dominik,
Thanks a lot for the reply. What is the importance of setting the ac current to 1?

Thanks and Regards,
Vishesh

 

[BradtheRad]

What is the importance of setting the ac current to 1?

This method is often recommended so that a simulator (or our meters) gives direct readouts. V=AR needs little pondering if either A=1 or R=1.

 

[VisheshG24]

This method is often recommended so that a simulator (or our meters) gives direct readouts. V=AR needs little pondering if either A=1 or R=1.

I'm sorry, but I still didn't understand what you wanted to check by setting the AC current to 1. Does AC current 1 mean that the varying AC current has a max amplitude of 1? What does it achieve?

 

[BradtheRad]

This is one of those things about AC. In every case we must be aware which we're considering, whether a) peak voltage, or b) RMS voltage.

That's only part of the issue. In any case, we usually measure impedance by passing current through the component and then read what voltage develops. If we set it to 1 Ampere, then the voltage we read across the component is automatically equal to the component's impedance. Because V=A*R.

One Amp does no harm to virtual components even though we rarely do that to real hardware.

 

[VisheshG24]

So, what I understood is, we are making the current 1 to find the input and the output impedance and for a good tia both of these should be very low?

 

[BradtheRad]

I think that's a quick method to check our work as we calibrate our transimpedance amplifier.