The development of millimetre wave mixer diodes

A new format gallium arsenide beam lead diode that allows the total capacitance to be reduced sufficiently for applications throughout the millimeter waveband is discussed. Involving the use of low-melting-point glass, the design has high mechanical strength for ease of handling. Metal-organic chemical vapor deposition is used to provide the thin epitaxial layer required to minimize series resistance in the device. The millimeter wave performance of the diodes is demonstrated in microstrip mixer circuits operating at 90 GHz and 140 GHz. It is noted that the microstrip single-ended mixer at 140 GHz extends the technology already established to 100 GHz and includes a single crystal quartz substrate. The conversion loss of balanced mixers at 90 GHz is typically 6.5 dB, and the single-ended mixer at 140 GHz exhibits a loss of 7.0 dB.