A high precision CMOS bandgap reference

A high precision bandgap reference is presented. An exponential curvature compensation technique, which exploits the Ic-Vbe temperature characteristic of BJTs, is used to reduce the temperature coefficient (TC). A pre-regulator circuit is adopted to enhance the PSRR (power supply rejection ratio) performance. The bandgap uses the current mode approach to generate a reference voltage around 500 mV. With the conventional first-order compensation, the temperature coefficient is 14.6 ppm/degC over the range from -40degC to 85degC. Due to curvature compensation, an improved temperature drift of 7.04 ppm/degC is obtained. The PSRR of the reference voltage achieves 120 dB at low frequency.