AbstractA lattice‐matched InGaAs/InAlAs resonant tunnelling diode is studied as a video detector in the millimeter‐wave range. Tangential signal sensitivity and video resistance measurements are made as a function of bias and frequency. A tangential signal sensitivity of — 37 dBm (1 MHz amplifier bandwidth) with a corresponding video resistance of 350 Ω at 40 GHz has been measured. These results, to the best of our knowledge, are the first millimeter‐wave tangential signal sensitivity and video resistance results for a resonant tunnelli