Low-frequency noise measurement of a highly stable charge-meter

A successful effort is reported on an accurate measurement of the low-frequency (1/f) noise and the thermal stability of the charge-meter presented. These two parameters are very important for the charge-meter, as its main application is to interface capacitive sensors with extremely high long-term stability and low thermal drift. A measurement strategy for the low-frequency noise behavior of the charge-meter is reported. A particular test setup was built and a special test strategy was created to reduce the different kinds of external low-frequency interference to a minimum. This allowed the low-frequency component of the intrinsic input noise of the charge-meter to be measured accurately. An extremely low value of the low-frequency (1/f) noise with corner frequency 2 mHz, and a very high thermal stability of 2 ppm/K of the charge-meter, are reported.