The Design And Realization Of Low-voltage Low-noise High-performance Benchmark

With the popular use of electronic system powered by battery, the power dissipation, speed and precision of ADC are more important. As one of vital basic modules, voltage reference which can directly influence on characteristics of the whole system not only provides accurate bias voltages, but also plays the part of the compared voltages. So it's crucial to explore the reference for satisfying the system. The paper aims at designing a low power, high speed and high precision voltage reference for pipelined ADC using standard CMOS process.This paper bases on the bandgap reference's(BGR) performances and theory, which analyses limiting factors of the low power supply and solutions and includes all kinds of high-order temperature compensation method. By comparing and analyzing good points and bad points of all sorts of bandgap reference, a design technique suited for the ADC system is obtained.Making use of foregoing design techniques, a low power and high-order temperature compensation BGR with an amplifier and a start-up circuit is designed, which adopts a common-source and common-gate structure to improve the high power supply rejection ratio(PSRR). Using the SMIC 0.18μm process, the circuit is simulated under four corners with the simulation tool of Cadence. Under the type model, the results show that the temperature coefficient is 3.26ppm/℃in -40～125℃. At the room temperature(25℃), its PSRR is -71dB and start time is 61ns. Under 1.5V to 2.1V power supply, the output change of voltage is 0.43mV/V.Based on the demand of ADC system, the BGR is analyzed and modeled by a statistic method. Using the simulation tool of Matlab, the paper presentes process errors' influencing on the output voltage, which plays an important role in tape out.A model of voltage buffer is built, in which the buffer with the impendence load of resistors and switch capacitors is analyzed in detail and the relationship between the speed and resolution of ADC and buffer's gain-bandwidth and transconductance is obtained. Considering the differential reference must suppress effects of switch capacitors and high frequency noise, a totally new type of differential reference is designed. The results show that it has a low temperature coefficient and a capability of rejecting high frequency noise.Finally, the layout of all the circuit is designed with 1P6M mixed-signal CMOS process.