A low voltage operational amplifier cell with extended input common mode range for high voltage current sensing applications

A new operational amplifier cell for high voltage current sensing applications is presented in this paper. The proposed structure employs a fully low voltage input stage capable of tracking input common modes (CMs) ranging from GND rail to above the supply rail. Furthermore, a solution for ensuring the linearity of the amplifier over the entire operating voltages is discussed. The proposed circuit was implemented in a typical 0.25μm CMOS BCD technology and its performances were confirmed by simulations and silicon measurements.