A high voltage current sense amplifier with extended input common mode range based on a low voltage operational amplifier cell

This paper presents a current sense amplifier (CSA) capable of performing measurements at high input common mode (CM) voltages independent of the power supply rail. The proposed circuit employs a fully low voltage amplifier cell, a correction block for maintaining the linearity of the input stage over the entire input CM and a protection circuit against high differential input voltages (DIFF). Furthermore, a trimming procedure that enables the use of typical polysilicon gain resistors without losing accuracy and precision is discussed. The proposed architecture has been implemented in a standard 0.25μm BCD technology and its performances have been confirmed by both simulations and measurements.