A -122 dB PSRR curvature-compensated bandgap reference with cross-connected NPN

A cross-connected NPN bandgap reference (BGR) circuit with high power supply rejection ratio (PSRR) and low temperature coefficient (TC) is proposed by using curvature-compensated and pre-regulation techniques. Compared with the traditional BGR, it does not require an operational amplifier to clamp the voltage, but uses the voltage feedback of the cross-connected NPN to clamp the voltage, making the structure simpler and eliminating the need to design an operational amplifier. Additionally, by subtracting two nearly identical positive-temperature-coefficient currents, the circuit generates a new current with enhanced curvature, which is then used as a compensating current to reduce the overall temperature coefficient. This compensating current is subsequently scaled by different gain factors to accommodate process-corner variations and serve as a trimming current. Meanwhile, the pre-regulation circuit is respectively adopted to improve PSRR. The proposed BGR circuit is implemented in a 180-nm process, boasting a minimal active area of 0.016 mm${}^2$. Simulation results show that the BGR has a best TC of 4.13 ppm/${}^{°}C$ from −40 °C to 125 °C at 3.3 V, a PSRR of −122 dB at low frequencies, and a linear regulation (LR) of 0.0027 mV/V within the supply voltage range of 3.0 V to 3.6 V.