1–50-MHz VHF electromagnetic sensor-interface power-attenuation detector circuit

The natural but unwelcome byproduct of modern telecommunication systems is electromagnetic interference (EMI). These communication networks are dynamic and produce unpredictable position- and time-varying electromagnetic fields that interfere with sensitive high-performance electronics, for which shielding is often a necessity. The shield's ability to suppress electromagnetic noise, however, may change not only over time but also across environmental conditions. EMI sensors, as a result, play a critical role because arbitrarily over-sizing a shield to accommodate worst-case conditions is not an option in many portable and mobile applications. This paper presents a logarithmically compressed peak-detection EMI sensor-interface circuit that combines the complementary functional strengths of state-of-the-art power detectors to monitor and sense 1–50 MHz of EMI with 5-bit accuracy across 16 dB of dynamic range and under −40 to 40 °C. The proposed circuit and printed-circuit-board (PCB) embodiment compensate for temperature variations as well as diode-induced errors to maintain and improve accuracy across a wide operating range.