A Real-Time Low-Noise Ultrabroadband Time-Domain EMI Measurement System up to 18 GHz

In this paper, a novel time-domain electromagnetic interference (EMI) measurement system for the frequency range from 9 kHz to 18 GHz is presented. It combines ultrafast A-D conversion and real-time digital signal processing on a field-programmable-gate-array (FPGA) with ultrabroadband multistage down conversion. Emission measurements can be accelerated by several orders of magnitude in comparison with measurements using traditional heterodyne EMI-receivers. With its IF dynamic range of over 60 dB, the system fully complies with the requirements stated by CISPR 16-1-1. The low system noise figure allows for high sensitivity. Measurements of the radiated EMI spectra and time behavior of several devices under test up to 18 GHz are presented.