Biasing a Transistor with Min. Noise Level

Thread Starter


Joined Jun 30, 2020
Hi, I need to bias a transistor on a sensor chip (the MOSFET is my sensor). My application is very noise sensitive since I am trying to measure a drain current signal change of only ~ 10 -80 nA.

Would it be a good idea to bias my transistor using a micro-controller controlled ADC (for example: ADG1606 with ON-resistance of 4.5 Ohm, leakage current < 5 nA which has a programmable current output 100 uA - 1000 uA)? Or should I stick with a benchtop high resolution, stable current/voltage supply? What method would introduce least noise in the experiment system?

If I go with trying to bias my transistor sensor chip with an on-PCB ADG16060 bias current, what other parameters of the ADC should I study to make sure the noise level of ADC current output is minimal? Do the bias conditions affect the noise of the test chip/transistor at all? Can I have a noisy bias supply and still measure a low signal if my signal measurement instrument is high resolution?

Thanks a lot.


Joined Oct 2, 2009
It would be very difficult to advise you without knowing the big picture.
What are you trying to do? Not about measuring drain current. What are you sensing?
Show as a circuit diagram.