Design of a Low Temperature Coefficient Bandgap Reference with High PSRR

Based on SMIC's 0.18 μm CMOS process,a bandgap circuit with low temperature coefficient and high PSRR is proposed.The circuit is applied in mixed-signal circuits such as DAC or ADC.In view of the operating voltage limitation in the conventional bandgap reference,the design adopts the current mode structure so as to work in low supply voltage,and the output reference voltage adjustable.In order to improve PSRR,the cascode current source is applied.It utilizes common two stage operational amplifier with high gain and high output swing.Cadence simulation showed that,at 1.8 V supply,the proposed bandgap reference had an output reference voltage of 534 mV;It achieved a temperature coefficient of 4.8 ppm/℃ in the temperature range from-25~100℃,and a PSRR of-84 dB,with a line voltage regulation at 1.6~2.0 V.