A low-noise realtime time-domain EMI measurement system

Time-domain EMI Measurement Systems allow to reduce the measurement time by several orders of magnitude. In this paper a realtime operating low-noise multiresolution timedomain EMI measurement system is presented. With a noise figure of about 7.5 dB and a high dynamic range emission measurements can be carried out close to the noise floor, while a high overload protection is available. A novel implementation of the 9 kHz IF-filter for the frequency 150 kHz to 1 GHz is presented. By this way the measurement time has been reduced by a factor of 8000 in comparison to conventional EMI Receivers. During emission measurements performed with a modelled IFbandwidth of 9 kHz the noise floor is decreased to -19 dμV in the average detector mode.Measurements have been performed with the improved measurement system in the frequency range 30 MHz - 1 GHz.