Variable-Temperature Noise Characterization of N-MOSFETs Using an
In-Situ Broadband Amplifier
AbstractCharacterization of broadband noise of MOSFETs from room temperature
down to 120 K in fine temperature steps is presented. A MOSFET is
mounted on a reusable printed circuit board vehicle with a built-in
low-noise amplifier, and the vehicle is loaded into a cryogenic chamber.
The vehicle allows noise measurement in the frequency range from 50 kHz
to 100 MHz. At low frequencies, it enables extraction of activation
energies associated with electron trapping sites. At high frequencies,
as has been suggested by noise figure measurements, the white noise of
MOSFETs is shown to be dominated by the shot noise, which has much
weaker temperature dependence than the thermal noise. The shot noise
will be a problematic noise source in broadband RF CMOS circuits
operating at cryogenic temperatures.