New Mixer Design Notes

This mixer is based on a passive FET resistive frequency converter cell described by first described in the literature by Steven Maas [ ] and explored by Wes Hayward and others [ ]. One difficulty with a DFET passive mixer is obtaining negative gate bias. This has been achieved using gate conduction as in the TriQuint 5M31 [Campbell, Criss], a LO frequency driven negative voltage converter as in the Phillips CMY-12 [Roke Manor Research], and pinch-off generators [Campbell, Hayward]. A different method of obtaining negative gate bias is used here. The mixer source and drain float above ground on a bypass capacitor C2. The source voltage of the following common gate IF amplifier is DC coupled to the mixer source and drain using inductors L1 and L2. This results in a mixer biased approximately halfway between 0 volts and Vp for J1. Other mixer and IF amplifier design details have been previously covered in the literature, but will be reviewed here as an application note.