ANALOG-DIGITAL CONVERTER OF WIDEBAND SIGNALS WITH CORRECTION OF LINEARITY ERRORS

Abstract

The widespread use of analog-to-digital converters (ADC) in computer systems is hindered by low resolution when converting signals in a wide frequency band. These problems are related both to the lack of the necessary elementary base and to the complexity of the processes of analog-digital conversion of broadband signals random in time, the mathematical representation of which in the time and frequency dimensions is quite complex. This results in high linearity errors of the ADC, which reduce the efficiency of the analog-to-digital conversion of broadband signals in computer systems. It is proposed to solve the problem of increasing the resolution of broadband analog-to-digital conversion devices by increasing the linearity of the ADC. A modified method of increasing the linearity of the ADC by adjusting it in the dynamic mode is presented. Such adjustment is performed by using a statistical methodology for evaluating the characteristics of broadband signals. The use of a test effect in the form of a multi-tone signal during calibration of the ADC is justified. The proposed test signal has a frequency spectrum enriched with fundamental harmonics and can be implemented using a wide class of standard sinusoidal signal generators with normalized metrological characteristics. At the same time, such a test signal makes it possible to ensure the operation modes of the ADC that are adequate to the real conditions of operation of analog-to-code converters. In order to maintain the high speed of the ADC, it is proposed to perform the adjustment by replacing the source code of the ADC with the corrected code. A structural diagram of the device for analog-to-digital conversion of broadband signals with correction of linearity errors has been developed, in which digital-to-analog formation of the test signal and tabular formation of corrected codes are used. An analysis of the dynamic parameters of the ADC with linearity error correction was performed, which confirmed the high efficiency of the proposed method of statistical evaluation and error correction and the high resolution of the constructed ADC structure.