Low-Supply Current-Mode Bandgap Reference Design

Reference circuits are crucial building blocks in analog circuits and are commonly used in analog to digital converters,whereby the analog voltage is compared to various reference levels to determine the corresponding digital values.They are also used in dynamic random access memories(DRAMs),flash memories,power supply generations,DC bias voltage and digital to analog converter(DAC).In this thesis,a low-supply current-mode CMOS bandgap reference(BGR)independent of temperature and supply voltage is designed with high robustness.The circuit provides a stable output voltage of 0.6V under a wide junction temperature range of 0~100 degree Celsius and a supply voltage range of 0.8~1.8V.The design was implemented using 180 nm CMOS technology and simulated through cadence software set up in the analog environment.The circuit when operating under low supply voltage is less sensitive to mismatch and haslow power dissipation.The design consists of fold-cascode operational amplifier(OTA),current mirrors,start-up circuit and biasing circuit.Simulation results obtained from the designed circuit shows a temperature coefficient of 20ppm/°C is achieved.Chapter I and II introduce the background of reference circuits,the existing implementations done by otherresearchers and the various methods used to reduce the power supply.Chapter III and IV clarify the detail design implementation of the proposed reference circuits and give the abundant simulation results.