Patent ID: 6993312
Filing Date: 2006-01-31
Classification: H03D

Abstract:
1. A double balanced signal mixer, comprising: a first and second balun type transformer, each having interwound pairs of series connected primary and secondary windings; a radio frequency (RF) input port connected to one end of the pair of primary windings of the first transformer and a ground connection connected to the other end of the pair of primary windings of said the first transformer; a local oscillator (LO) input port connected to one end of the primary windings of the second transformer and a ground connection connected to the other end of the pair of primary windings of the second transformer; an intermediate frequency (IF) output port connected via a signal coupling circuit to a center tap connection between the secondary windings of the first transformer; a ground connection connected to a center tap between the secondary windings of the second transformer; a diode quad in the form of a bridge circuit comprised of four circuit arms interconnected by opposing pairs of bridge terminals, each of said arms including a plurality of series connected diodes, one of said pair of opposing bridge terminals being connected across the secondary windings of the first transformer, and the other of said pair of opposing bridge terminals being connected across the pair of secondary windings of the second transformer; and means coupled at the RF side of the mixer between the bridge circuit and the first transformer for reducing intermodulation products and, thereby, improving the third order intercept point of the mixer.