Research On High Precision ADCs Test Method Based On DSP

With the development of science and technology,analog-to-digital converters(ADC)are widely used in various fields such as data acquisition systems,automatic testing,industrial control,communication and measurement.And the precision requirements of ADC are also increasing in various industries.Digital signal processing technology(DSP)has fast digital data processing capability,and is gradually applied in the field of ADC testing,through the fast fourier transform(FFT)transformation,the spectrum information of the signal after the ADC sampling can be calculated,so that the frequency domain parameter test of the ADC in the frequency domain is realized.In this thesis,FFT method to test the frequency domain parameters of high precision ADC,and to solve the influence of high precision ADC test of input signal,the existence of spectrum leakage and fence effect,and how to improve the test accuracy by algorithm optimization.The main research contents are as follows:Firstly,in order to solve the problem of spectrum leakage in high-precision ADC frequency domain parameter testing under incoherent sampling conditions,the influence of window function performance on ADC frequency domain parameter testing is explained by adding combined cosine window function.By studying the performance and designing method of the combined cosine window function,and analyzes how to select and design the window function to reduce the influence of spectrum leakage.Secondly,because of the fence effect of FFT test under incoherent sampling,the influence of the fence effect is reduced by the frequency domain interpolation algorithm,the double spectral line and the three spectral line interpolation algorithm are deeply expounded,and the amplitude of the ADC frequency domain parameter test is corrected by using the window interpolation calculation.Thirdly,it is because the high precision ADC test has high requirements for the purity of the input signal.In order to reduce the demand for high-precision signal sources,hardware platforms and algorithms are used to generate test signals.And it ensures that the amplitude and phase of the fundamental signal are matched in the algorithm processing.Then the fundamental signal is identified by the algorithm,so that the nonlinearity of the main DAC can be estimated.Finally,the corresponding calibration DAC verification code is generated according to the nonlinearity of the estimated main DAC.and the high-purity sinusoidal wave signals are generated by continuous iteration of the algorithm.Finally,a hardware test platform is built to generate the test signals.On the hardware test platform can use window interpolation calculation to complete the frequency domain parameter test of under test ADC chip.The correctness and feasibility of the test algorithm can be verified on the hardware test platform.The most important is that can be reduced testing cost of the high precision ADC frequency domain parameter test.Compared with the traditional FFT test results,the frequency-domain parameter testing accuracy of ADC model AD7626 can be improved effectively by windowed interpolation,but the testing time can be increased.It can be applied to ADC test system to reduce the requirement for testing instruments and provide a possibility for low-cost and high precision ADC test.