Research On High Speed Low Power A/D Converter And Related Technique

With the rapid development of CMOS process, more and more singnal processing is processed in digital domain to achieve high speed and low power with low cost. While most of the signal in our reality world is anglog, analog-to-digital (A/D) converters are required to tansform analog signal into digital signal for processing. The speed and power have become the key factors to evaluate its performance, which are important factors to determine whether they can be used in communication network and portable video equipment.A high speed low power pipelined interpolating A/D converter is implemented; the disadvantage of its performance easily affected by the supply variation is analyzed and given. In order to improve its power supply rejection, an on-chip LDO regulator is applied in the high speed, low power pipelined interpolating A/D converter. The related techniques of bandgap refereance and LDO regulator applied in the pipelined interpolating A/D converter are investigated. The thesis includes the following aspects:A high speed pipelined interpolating A/D converter is implemented. A three-stage pipeline chopper inverter phase amplifier, capacitive interpolation and pre-equalized comparator are utilized to achieve high speed and low power. The clock generator and output encode circuit is given. The pipeined interpolating A/D converter is fabricated and measured. The affection of supply ripple on the performance of the A/D converter is analyzed and the simulaton result of the A/D convter in low voltage is given.Low voltage curvature corrected bandgap references are designed. A piecewise nonlinear curvature corrected current generator based on temperature related ratio is proposed. In the low, middle and high temperature range, the curvature-corrected current is zero, proportion to expontial and squared with temperature respectively. The nonlinear curvature corrteded current generator is utilized in a low voltage current-mode bandgap reference to design a 1V curvature corrected bandgap reference with low temperature coefficient. Applying the nonlinear curvature corrected current generator in a voltage-mode bandgap reference, a curvature corrtected bandgap reference with negative is designed and implemented. The distinguish feature is a negative is formed between the curvature corrected current generator and the output circuit. The two objects of decreaseing the temperature coefficient, improveing power supply rejection (PSR) and line regulation are achieved with only one circuit module. The negative is simple, which needs little extra chip area and power consumption. Experiment results shows the design consideration is correct.The implementation technique of low noise LDO regulator for on-chip application is investigated. The relation of line regulation and load regulation with circuit parameters for the LDO regulator with pre-regulator is analyzed briefly. A CMOS low noise, high PSR LDO regulators for on-chip application is implemented. A sharing pre-regulator for LDO regulator is proposed. The pre-regulator is designed based on current negative feedback, which dramatically decreases the sentivity of its bandgap reference performance with the variation of threshold, increases the PSR of its bandgap reference, and decreases the output noise of the LDO regulator. The architecture of the sharing pre-regulator is applied in an invention patent.A high speed low power A/D converter with on-chip LDO regulatos is designed, which includes reference generator, low noise LDO regulator and a pipelined interpolating A/D converter. The 1V curvature corrected bandgap reference is utilized in the A/D converters, which is followed by a level shifter and two buffers to provide the top and bottom references for the A/D converter. Another output of level shifter forms a pre-regulator. The pre-regulator and the followed two power drive stages form a dual output low noise LDO regulator, which provides supply for the analog and digital module. The circuit parameters of the pipelined interpolating are optimized to achieve high speed, low voltage and low power. Simulated results show the designed A/D converter has the advantages of high speed, low power and large operating volateg range.