- #1
Wapochief
- 27
- 0
Hi Guys and Gals,
I am trying to linearly amplify a 1nA-10nA current to 1V-10V. I need at least 10KHz bandwidth. I have tried using a 3 stage amplification (negative feedback) system using an lt1012 op-amp (1 nA to 1mv, then 100,10 gain), but the noise is very high (-30/40 db). I need at least -50 db.
I have built the circuit with surface mount components on PCB, with a ground plane and enclosed in a grounded metal box. I have voltage regulators, as well as capacitors to reduce supply voltage noise.
Another strange thing is that the gain increases (yes, increases!) with frequency, and I expected the gain to be flat and then roll off as frequency increased. The real world behavior of this circuit in no way matches any of the simulations I have done.
Is there any other way to amplify that small of a current with low noise? I have found transimpedance amplifiers, but they are for uA up.
Thanks,
Wapo
I am trying to linearly amplify a 1nA-10nA current to 1V-10V. I need at least 10KHz bandwidth. I have tried using a 3 stage amplification (negative feedback) system using an lt1012 op-amp (1 nA to 1mv, then 100,10 gain), but the noise is very high (-30/40 db). I need at least -50 db.
I have built the circuit with surface mount components on PCB, with a ground plane and enclosed in a grounded metal box. I have voltage regulators, as well as capacitors to reduce supply voltage noise.
Another strange thing is that the gain increases (yes, increases!) with frequency, and I expected the gain to be flat and then roll off as frequency increased. The real world behavior of this circuit in no way matches any of the simulations I have done.
Is there any other way to amplify that small of a current with low noise? I have found transimpedance amplifiers, but they are for uA up.
Thanks,
Wapo