dave6877 said:
The DC output level of the TIA is at 1mV. The AC output is from that 0uV to 200uV.
So output of TIA = 1mV(1mV+0uV)(lower limit) to 1.2mV(1mV+200uV)(higher limit).
I need the output of the amplifier lower limit to be below 2V and the higher limit above 3V.
You have to tell me exactly the output, not just below 2V and above 3V, I use 2V and 3V here:
1) For signal, you want to map (0 to 0.2mV) to (0 to 1V)\Rightarrow\; Gain=5000
2) DC offset is from 1mV to 2V so offset gain is 2000.
You are going to need two op-amp to do this.
Question:
1) what power supply do you have?
2) how stable is the 1mV offset of the TIA as I am not familiar with TIA. If it drift a lot, you are going to have problem.
3) Can you use two power supply so you can have +ve and -ve?
4) If the signal is 1KHz, can you use an AC coupling cap to get rid of the 1mV DC offset so you can start at ground level of -100uV to +100uV. This will eliminate a lot of uncertainty on the stability of the DC offset from the TIA.
5) can you accept inverted signal?
This is not exactly an easy circuit, you have to create an offset null for the offset. First pass, you need two inverting amp to do it. It would be more complicated if you have only positive supply and try to create the offset. If you can use an AC coupling cap, it is going to be easier, but you still are going to need 2 op-amp as you need a gain of 5000 and you need an op-amp of at least BGW of 5MHz or above. I don't like to use wide band op-amp if I don't need it.