A low-noise multiresolution high-dynamic ultra-broad-band time-domain EMI measurement system

A time-domain electromagnetic interference (EMI) measurement system allows to reduce measurement time by several orders of magnitude in comparison with conventional systems. This will considerably reduce the costs of compliance tests. In this paper, a novel multiresolution time-domain EMI measurement system is presented. The multiresolution time-domain EMI measurement system exhibits several channels with limiters, amplifiers, and analog-to-digital converters. The amplitude range of the signal is subdivided into several intervals. In each interval the analog-to-digital conversion is performed with an amplitude discretization proportional to the width of the amplitude interval. The signal-to-noise ratio of the multiresolution time-domain EMI measurement system compared with a conventional time-domain measurement system for transient signals is enhanced by at least 50 dB. It is shown that the multiresolution time-domain EMI measurement system has a higher overload factor than conventional systems working frequency domain. The noise floor is 5 dB lower than the noise floor of a conventional EMI receiver. The multiresolution time-domain EMI measurement system shows a higher 1-dB compression point than conventional EMI receivers. Measurements were performed in the frequency range from 30 MHz to 1 GHz and compared with results obtained by an EMI receiver.