High-frequency mixers using square-law diodes

The use of symmetrical and asymmetrical space charge limited (s.c.l.) square-law diodes as mixer elements is considered, and it is shown that low conversion loss is possible with the latter type. In order to achieve this a d.c. bias is necessary on the diode. Matching source and load resistances are higher than for the unbiased diode. The use of an idler termination at the sum frequency (p+q) is shown to have some advantages. The symmetrical diode is shown to be unpromising as a mixer element.