Integrated voltage reference and comparator circuits for GaN smart power chip technology

GaN smart power chip technology has been realized using GaN-on-Si HEMT platform, featuring monolithically integrated high-voltage power devices and low-voltage peripheral devices for mixed-signal functional blocks. Two imperative functional blocks for smart power applications with wide-temperature-range stability are demonstrated. The first one is a voltage reference generator, and the second one is a temperature-compensated comparator. These circuits are capable of proper functions within a wide temperature range from room temperature up to 250degC, illustrating the unique advantage of the wide-bandgap GaN. The voltage reference generator was designed with an AlGaN/GaN HEMT and Schottky diodes, and the devices were operated in the subthreshold regime to obtain low power consumption. The voltage reference generator achieved an average drift of less than 70 ppm/degC and can be used as a reference voltage in various biasing and sensing circuits. The temperature-dependent performance of a conventional comparator is characterized and a new temperature-compensated comparator circuit is proposed. The positive limiting level of the temperature-compensated comparator is less than 450 ppm/degC drift compared to 1350 ppm/degC in the conventional comparator.