Low-Cost Broadband Electronic Coupler for Estimation of Radiated Emission of Integrated Circuits in TEM Cell

Transverse electromagnetic (TEM) cell is a well-known method for the qualification of radiated electromagnetic emission from integrated circuits (ICs). Combined with a 180 degrees hybrid coupler, it provides a simple method for quantifying radiated emission (RE). However, typical transformer or coupled line based hybrid couplers have limited bandwidth which cannot cover the full frequency range required by IC emission tests (150 kHz to 1 GHz). This article presents the design and the validation of a low-cost broadband electronic version of a 180 degrees hybrid coupler dedicated to the estimation of radiation emission from TEM cell measurements. The proposed prototype is able to cover a large frequency range (from dc to 1 GHz) with a sufficient sensitivity and dynamic range for RE tests in TEM cell. The cost of the presented coupler is very reasonable as it is entirely based on commercial operational amplifiers.