This amplifier has a fixed 100x dc-gain and an ac-gain of 100..100k V/V
It can be used for ac lownoise measurements or fixed gain 100 dc-measurements. Noise at 1kHz is 12x lower compared to the general purpose amp M2/M2m but drift, offset and input current are higher.
The M2b has better dc-specs but a higher noise >10Hz.
The design is based on a discrete dual JFET-input stage, care should be taken not to damage the input by overloading it (>1V can cause damage).
The amplifier contains no chopper or oscillating circuits that could produce interference
specs:
Input noise voltage: 0.8nV/sqrt Hz >10Hz
Input noise current: 50fA/sqrtHz
Input bias current : <50pA
Temp drift : <5uV/c
Bandwidth : 200kHz..10kHz (gain=100..100K)