Research And Design Of CMOS Bandgap Reference Source

CMOS Bandgap Reference (BGR) source is widely used in many circuits, such as ADC, DAC, LDO and other analog or mixed circuits. It is an essential block. Its performance directly affects the accuracy and system stability.In this paper, three different types of BGR used in pipeline ADC, DAC and LDO are researched.Research and design the BGR in ADC, including the core circuit, operational amplifier, bias circuit and start circuit. Basing on a typical brokaw structure, two op amps are used to achieve voltage clamp spaces and provide a stable bias voltage, Feedback designe to improve the baseline by the power supply rejection ratio. The BGR applied in DAC uses different types of resistance to second-order compensation. The temperature characteristics are significantly improved. The BGR applied in LDO uses compensation of base current and the substrate voltage module technology. Finally, taking full account of various factors on the basis of layout, design the layout of the BGR used in pipeline ADC, and through layout verification.The BGR applied in ADC ,based on chart0.18μm CMOS process, with 1.8V supply, temperature coefficient (TC) is 8.5ppm/°C , Power supply rejection ratio (PSRR) is 110.2dB. The BGR applied in DAC, with SMIC0.35μm and 3.3V supply, TC is 2.7ppm/°C ; PSRR is 85dB. The BGR applied in LDO, with Hynix0.5μm process and 5V supply shows that TC is 37ppm/°C , PSRR is 75.4dB. The performance of three circuits can satisfy the corresponding system requirements.