Patent ID: 6400936
Filing Date: 2002-06-04
Classification: H03D,H03F

Abstract:
A low-noise lossless feedback double-balanced active mixer circuit for mixing an input intermediate frequency (IF) signal and an input local oscillator (LO) signal and producing an output radio frequency (RF) signal consisting of:a pair of IF input terminals for receiving differential first and second IF signals, the first IF signal input terminal receiving the first IF input signal and the second IF signal input terminal receiving the second IF input signal; a pair of LO input terminals for receiving differential first and second LO input signals; an RF output terminal for providing an RF output signal; a first low-noise lossless feedback balanced active mixer circuit having an IF signal input coupled to the first IF signal input terminal, first and second differential LO signal inputs coupled to the pair of LO input terminals, a first differential pair of transistors having a signal input, a differential pair of LO inputs coupled to the first and second differential LO signal inputs, and a differential pair of outputs coupled through a first hybrid transformer to an RF output connected to the RF output terminal, the first hybrid transformer further providing a first amplified IF output, and a first lossless feedback transformer coupling the first IF signal input and the first amplified IF output of the first hybrid transformer to the input of the first differential pair of transistors; and a second low-noise lossless feedback balanced active mixer circuit having an IF signal input coupled to the second IF signal input terminal, first and second differential LO signal inputs coupled to the pair of LO input terminals, a second differential pair of transistors having a signal input, a differential pair of LO inputs coupled to the first and second differential LO signal inputs, and a differential pair of outputs coupled through a second hybrid transformer to an RF output coupled to the RF output terminal, the second hybrid transformer further providing a second amplified IF output, and a second lossless feedback transformer coupling the second IF signal input and the second amplified IF output of the second hybrid transformer to the input of the second differential pair of transistors.