Hello, I need measure voltage difference between centr and shield coaxial cable (not groud).
Signal frequency 2MHz voltage 50uV - 100mV, amplifier gain 1x
So far, I consider the use of AD8620+AD8610 is a better option, or integrated instrumentation amplifier?
Or any other construction I can think of difference amplifier and Jfet Q as buffer for big input resistance or ...
Just for Analysis or design? A spectrum Analyzer would be far superior. Got one?
High impedance? Why? Ingres test?
Better to use BPF to reduce noise factor if possible.
ADA4897-1 is good idea, but my design work with +-12V power supply.
Signal is pure sinus symmetric around 0.
Impedance , I thing input current < ~20pA.
BFP can not be used (phase and time shift).
Any case, thank you for drawing attention to the new amplifier!
You didn't clearly tell about the intended pA bias current.
As far as I see there aren't much more JFET OP candidates than AD8620 (6nV/√HZ) and TI OP140 (5.1 nV/√HZ) for your application. Also discrete JFET amplifiers don't perform better.