A Study Of System Modeling And Verification On High Speed D/A Converter

Digital-to-Analog converter is an essential interface component which is widely used in modern digital and analog circuits. With the rapid development of wireless mobile communication technology,the requirement on performance of data converter is getting more rigorous and more. In order to satisfy the demand on the growth of high definition of digital audio, video and contemporary wireless communication, the dissertation has studied a type of segmented current source digital-to-analog converter's systematic class model with high sampling rate and validated the characteristic parameters of digital-to-analog converter by software simulation.Based on the existing theory of digital-to-analog converter, the dissertation mainly has studied the mathematical-analysed relationship of integrated nonlinearity, differential nonlinearity, signal noise distortion ratio, and spurious free dynamic range among error in input encode, error in unit current source mismatch, circuit noise and output impedance. Having established the function model of integrated nonlinearity, differential nonlinearity, signal noise distortion ratio, and spurious free dynamic range, on the base of which a systematic class model of digital-to-analog converter is founded. The unit current source mismatch consists of random error and gradient error, the former one could not be avoided but the later one could be eliminated by appropriate layout design, which could decrease the differential nonlinearity. On the other hand, the integrated nonlinearity is independent of the architecture of digital-to-analog converter, However, a proper architecture of digital-to-analog converter could reduce the differential nonlinearity.By utilizing the systematic model, under Matlab circumstance, the dissertation has simulated the nonlinearity and spurious free dynamic range of the digital-to-analog converter with 14 Bit, 125 MHz sampling rate. The result implies that when the full scale sinusoid input signal with 60MHz, the spurious free dynamic range of the digital-to-analog converter could obtain 90 dB, the integrated nonlinearity is less than ?1 LSB and the differential nonlinearity is less than ?0.5 LSB, which indicates signal setting precision is fulfilled with 125 MHz sampling rate.