Design Of Reference Voltage Source In 12bit 50MSPS Pipelined ADC

Pipelined ADC is widely used in communication systems and sensor systems as a type of high-speed and high-resolution converter.Reference voltage source is generally used to provide reference voltages for pipelined ADC,and drives ADC convertion.So its performance directly affects the function of ADC.In this thesis,a reference voltage source is designed for a 12bit 50MSPS pipelined ADC,which consists of a bandgap voltage reference and a reference voltage buffer.The bandgap voltage reference is designed based on the current-mode bandgap principle.To restrain the mismatch of current mirror,an opamp is used to clamp the voltages of the drains of current mirror.A method of curvature temperature compensation utilizing the the temperature characteristic of resistors is adopted to improve the temperature coefficient.The method doesn't add extra process flow because it doesn't use different types of resistors,and it doesn't add eatra power consumption either.A start-up circuit with capacitor is utilized.A method of leakage-current-compensation is used to refrain the deviation caused by leakage current in start-up circuit.The reference voltage buffer is designed by the method of replica source-follower.The reference voltage is produced by opamp feedback and series resistors,and the ADC convertion is driven by replica source-followers.The reference voltages for MDAC and Sub-ADC are isolated from each other to prevent interference.The proposed circuit is designed based on TSMC 0.13?m CMOS process and the circuit design,pre-simulation,layout design and post-simulation are performed.The result of post-simulation is as follow:the temperature coefficient of bandgap reference is below 2ppm/?(The temperature is from-450C to 85?).The PSRR of reference voltages is more than 60dB.When converting input signal with Nyquist frequency,the 12bit 50MSPS pipelined ADC driven by the proposed reference voltage source has the SFDR of 83dB and the ENOB of more than 11bit.The proposed reference voltage source consumes 1mA at 1.2V supply,and the power consumption is 1.32mW.The simulation result above meets the design requirement.