Effective Number of Bits of the Microwave ADC with Account for the Dynamic Error of the Input Transformer

Abstract

At ultrahigh frequencies (microwave), the signal from the analog sensor in the analog-to-digital control and monitoring systems is entered according to the well-known scheme of series connection of an input microwave transformer (IMT) and an ADC. In this case, the IMT becomes an integral part of the ADC.The article shows that the dynamic error, determined by the information delay in these two devices, is added to the static error and actually reduces the ADC number of bits. This decrease can be estimated by the effective number of bits determined by the delay time and the required sampling rate of the input signal. To estimate the delay value in such a way, the analysis of the processes in the ADC input microwave transformer has been carried out. In this case, the dynamic aliasing error, which occurs during the time sampling of the input signals in the microwave ADC, is taken into account.The analysis of the results obtained on the example of microwave ADC AD9208 shows that the dynamic errors of the IT have a significant effect on the value of the effective number of bits of the ADC.