[time-nuts] Re: +1/f of transistors

[Lux, Jim]

On 4/10/22 2:50 AM, Leon Pavlovic wrote:
> What would be a (very) good lab setup for the 1/f noise evaluation? I'm
> talking about BJTs and JFETs.
>
> What instrumentation and power supply are needed? How not to measure in a
> wrong way - like 1/f noise in the instrumentation or the power supply
> circuitry? Active collector/drain current sources vs pure resistive...
>
> I'm quite familiar with the low NF measurements, so I guess the same
> practice would apply: insert your DUT, short its input side, have a
> low-noise post amp and display the noise on FFT SA?
> _______________________________________________


Except that just like for microwave amplifiers, the noise depends on the 
impedances.

Shorting the input of an opamp will give you the noise voltage, but not 
the noise current. Putting a known resistor gives you the noise current 
(as IR plus the noise voltage plus the noise of the resistor)

For devices, I would think you set up a standardized circuit (every 
application is different, so that's a challenge).