Dear all,
For research purposes, I need to acquire near-infrared light emission over several decades, starting at very low values.
I plan to use a FCI-InGaAs-120 photodiode in photovoltaic mode. Light in the 1100nm field focused on the diode should range from 5nW to 50mW. The design of a TI-amp eventually followed by a non inverting amp present no difficulties (TI notes and circuit examples), only a big (variable) resistor is needed. OP-Amp requires extremely low input current (~pA) and low noise (<10nV/sqrt(Hz)).
Considering the acquisition circuit will be in a remote place, the gain of the transimpedance amplifier has to be set by some means. So far I considered motorized potentiometers but their lack of feedback and 20% tolerance make the design weak though easy. A set of precision resistances shorted by relays may induce noise in my very weak signal.
Could someone help me with a solution asides VCR2N (too low range) and LT1228 (too much input current)?
Thanks a lot.
For research purposes, I need to acquire near-infrared light emission over several decades, starting at very low values.
I plan to use a FCI-InGaAs-120 photodiode in photovoltaic mode. Light in the 1100nm field focused on the diode should range from 5nW to 50mW. The design of a TI-amp eventually followed by a non inverting amp present no difficulties (TI notes and circuit examples), only a big (variable) resistor is needed. OP-Amp requires extremely low input current (~pA) and low noise (<10nV/sqrt(Hz)).
Considering the acquisition circuit will be in a remote place, the gain of the transimpedance amplifier has to be set by some means. So far I considered motorized potentiometers but their lack of feedback and 20% tolerance make the design weak though easy. A set of precision resistances shorted by relays may induce noise in my very weak signal.
Could someone help me with a solution asides VCR2N (too low range) and LT1228 (too much input current)?
Thanks a lot.