High accuracy measurement of low-frequency noise in front-end P-channel FETs

The paper describes the instrumentation that was developed to allow series noise spectral analysis on field effect transistors. Analog interfaces between the device under test and commercial available analysers, working in the frequency range 100 mHz–100 kHz, have been designed and realised. The intrinsic noise contribution of the interface is estimated to be 1 nV/ Hz at 100 mHz and 50pV/ Hz beyond 1 kHz. The basic idea is to amplify the noise of the device under test through a capacitive feedback loop, which is theoretically noiseless. The paper is focused on the design and the performances of the interface for the noise characterisation of p-channel FETs.