A Precision Current Sense Amplifier With Disable Function

This paper presents a precision current sense amplifier (CSA) with extended common mode range and disable function. For minimum power consumption while in Disable mode, the current path through the resistive network is disconnected by a pair of switches. While in Enable mode, the switches' resistances must be kept low to meet the offset and gain error specifications. Characteristics of the presented amplifier include an input voltage range of 40V, a fixed gain of 50V/V with a typical gain error (GE) of 0.1% and an offset voltage (V_OS) lower than 50μV. The supply voltage can vary from 1.8V to 5V, with a maximum quiescent current of 45μA. The proposed architecture has been implemented in a standard 0.25μm BCD technology and its performances have been confirmed by both simulations and measurements.