Correlation spectrum analyzer for direct measurement of device current noise

Abstract

This article analyzes the realization and the performance of a correlation spectrum analyzer specifically conceived to directly measure the current noise produced by electronic devices with maximum sensitivity. The text describes in detail and gives the design rules of the instrument input amplifiers taking into consideration noise, dynamic range, stability, and bandwidth, together with the effects that a device under test (DUT) having complex impedance introduce. This article shows that the proposed scheme may allow current noise measurements with a sensitivity improved by few orders of magnitude with respect to a standard spectrum analyzer and to a correlation analyzer in voltage scheme whenever the DUT has an impedance larger than few 10 kΩ. Such a sensitivity makes the proposed instrument ideal for the characterization of advanced devices, such as ultrashort channel metal-oxide-semiconductor field effect transistors, mesoscopic junctions, or spin dependent electron transfer devices where it may be necessary to detect noise levels as low as fA/Hz.