Design Of A 12 Bit Successive Approximation Register ADC In SoC System

As an essential component of the SoC system in use, Analog to Digital Converter(ADC) modules are combined with other analog or digital modules in one chip because of the SoC systematic requisition for performance, such as high performance, low consumption, low cost, etc.. This is the trend of the times. For this reason, it is very necessary to design an ADC module compatible with digital technology.Successive approximation register analog-to-digital converter is a common architecture. It has the characteristics of low power and small size, thus is used in SoC system. In this paper, I design an ADC module in SoC used for touch screen which contains comparator circuit, DAC circuit, mux circuit and touch screen circuit in analog circuit and clk circuit, shift register control circuit in digital circuit which based on the TSMC 0.18um 1P5M process. According to the demand of low power consumption and high speed, a new segmented current scaling DAC both with binary weighted and thermometer-code is presented, which can reduce the mismatch of MOS and the glitches, at the same time, the area is small and power consumption is low. Then, a preamplifier-latch comparator which has low kickback noise and high speed , a high driving ability touch screen circuit is presented. In this paper, the design of every block, the simulation of the circuit and the implementation of layout are given with the detail of the design process. The design can be simulated by tool like HSPICE, get the satisfied results and the final layout.