Design of voltage reference circuits

Abstract

Shrinking device dimensions in advancing CMOS technologies require lower supply voltages to ensure device reliability. As a result, analog circuit designers are faced with many challenges in finding new ways to build analog circuits that can operate at lower supply voltages while maintaining performance. Bandgap references are subject to these head-room problems especially when the required supply voltage approaches the bandgap voltage of silicon. However, the bandgap reference working with a low supply voltage often has a higher temperature coefficient than that of a traditional bandgap reference. This has resulted in the development of new temperature-compensated techniques. Piecewise linear curvature correction method is simple yet robust technique which was previously available in bipolar technology. This research work describes a Novel CMOS bandgap reference which uses piecewise-linear curvature compensation scheme for second order correction. In standard 0.18μm CMOS process, the reference, with 1.8 V supply produces an output of about 928 mV, which varies by 160 μV from -25 °C to 150°C. It dissipates 150 μW and has a DC PSRR of -46 dB.