The Research And Implementation Of High Resolution And High Speed DA Conversion Circuit

Data converter is the bridge between digital world and analog world,and plays an important role.In the digital era,analog signals still have a wide range of applications,such as wireless communications,audio and video transmission,automatic control and other fields.Data converter is developing towards high-speed and high-resolution,which brings great challenges to chip testing.According to the test standard,high resolution A/D converter requires high purity waveforms with a resolution of 3-4 bits higher than that of A/D converter.In order to test these high resolution ADCs,it is necessary to study how to generate higher resolution waveforms without the use of higher resolution ADC chips.This dissertation mainly studies the high resolution and high speed DAC circuit used in the test of ADC chip.In this dissertation,we propose to improve the resolution of analog-to-digital converter by parallel digital-to-analog converter,analyze the noise in the circuit,and study the influence of digital preprocessing on the quality of output waveform.The main work and innovations of this subject include:(1)The requirement of high resolution and high purity signal in ADC testing and the challenges encountered in chip testing are studied.The structure and performance parameters of ADC are analyzed.The current methods of generating high resolution and high quality waveforms are compared.(2)This dissertation puts forward the way of parallel DAC to improve the resolution of DAC circuit,and gives the design scheme and implementation process of DAC circuit,adder circuit and reference source circuit.The test scheme of static and dynamic parameters of high resolution DAC circuit is given.(3)The filter circuit and amplitude control circuit after the digital-to-analog conversion circuit are designed,and the data input mode of the digital-to-analog conversion store is introduced.The noise that may be introduced into the analog-toanalog conversion circuit is analyzed,and the noise and error of each device and module are analyzed and calculated,so as to make a decision to choose the more suitable device.(4)The digital preprocessing method is studied to suppress the low-order harmonic distortion,and the second and third harmonic distortion can be suppressed by interleaving the signal phase.It also studies how to compensate the nonlinearity of the DAC circuit by predicting the INL of the tested ADC and the INL of the DAC circuit,and how to compensate the nonlinearity,so as to improve the purity of the output waveform.The digital-to-analog conversion circuit designed in this paper can achieve 24-bit resolution and 1M sampling rate.The quality of output waveform is improved after digital predistortion.The total harmonic distortion of output sinusoidal wave can reach-110 dB,and the effective digits can reach 18 bits.The effectiveness of the proposed method is proved by the test and analysis of indicators.