Operation of Current Mirror Circuit with Subthreshold MOSFETs

Abstract

A deviation of the mirrored current in paired MOSFETs operating in linear region is a serious problems. In this paper, an attenuator is added to diode connected MOSFET for operating in weak inversion region to suppress the mirrored current deviation. The operation of current mirror is derived from a MOSFET model based on diffusion current of pn junctions. The operation is confirmed by measured MOSFETs fabricated with a standard 0.18μ m n-well CMOS process. As the current of MOSFET operating in weak inversion is degraded for the current mirror circuit, a method to compensated the degraded current is also considered.