An HEMT with an integrated on-drain capacitor as basis of an hybrid mixer

This paper reports the study of an HEMT, the characteristic of which is to have a decoupling capacitor directly integrated between its drain and source electrodes. It is shown that, with an appropriate design of this basic filtering element, such a device proves to be efficient as for the realization of hybrid gate mixers. An experimental demonstration of this property is given by comparing a HEMT without capacitor with a HEMT with an integrated capacitor. For the latter, the gate length of which is 0.3 μm, it is shown that, at 18 GHz, a 5-dB improvement of conversion gain is provided by the integrated capacitor.