AbstractThe influence of via hole inductance on millimeter‐wave single‐ended pHEMT gate‐mixer down‐converter conversion gain is examined by a closed formula and by measurement. It is shown that feedback inductance acts as a voltage divider, reducing the conversion gain and increasing the LO power requirements. Analytical considerations presented in the paper predict that this effect can reduce the conversion gain by up to 9 dB. Additionally, a method to minimize the influence of via hole inductance on mixer performance is presented. Two circuits, one with and one without resonating stubs, have been manufactured and tested. The new circuit exhibits 3.5 dB more conversion gain than the classical topology, RF 65.3 GHz, nominal IF 1.3 GHz. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 399–400, 2002.