Design and implementation of BiCMOS based low temperature coefficient bandgap reference using 130nm technology

Abstract

BiCMOS bandgap reference (BGR) has advantage over MOS based BGR in terms of its accuracy at its reference output and very less temperature coefficient (TC). This paper presents bandgap reference circuit with folded cascode operational amplifier (op-amp) in order to improve the stability of final VREF output. The temperature stability of output can be improved by using trimming circuit in voltage mode architecture of bandgap reference operating with less power consumption. Using only first order temperature compensation technique, the proposed circuit gives output voltage of 1.181V with 0 °C to 100 °C temperature variations that corresponds to TC of 19ppm/ °C. The output reference voltage exhibits line variations of 2.4mV/V with supply range of 1.62V to 1.98V at typical process corner. A single stage folded cascode op-amp that is included in the proposed bandgap improves the stability of output voltage in closed loop, power supply rejection ratio (PSRR) of BGR and input common mode range. The proposed circuit includes start-up circuit to avoid start-up problem because of closed loop, the reference current for op-amp is generated from BGR current mirror and impact of its TC on final VREF is negligible. The simulation results shows that PSRR of proposed BGR is −43db from dc to 30KHz frequency, Phase margin (PM) is 70°, input offset of op-amp is 1.96μV and closed loop gain of op-amp in BGR is 118dB. The total current for overall BGR is 12μA and total power consumption is 18.4μW. The proposed bandgap reference is simulated using Mentor-Graphics Pyxis tool, Eldo-Spice simulator in 130nm CMOS technology. The proposed BGR output is used in low-drop-out (LDO) regulator circuit that is operating at 3.3V supply and gives regulated output of 1.8V.