Patent ID: 7463108
Filing Date: 2008-12-09
Classification: H03C,H04L

Abstract:
1. An active 90-degree phase shifter with LC-type emitter (source) degeneration, which is practiced in an integrated circuit, comprising: a first differential amplifier, having one first signal output end and comprising an inductor, a first transistor and a second transistor, said inductor is connected to the emitters (sources) of said first and said second transistors; and a second differential amplifier, having one second signal output end and comprising a capacitor, a third transistor and a fourth transistor, said capacitor is connected to the emitters (sources) of said third and said fourth transistors, wherein the bases (gates) of said first and said fourth transistors are signal input ends used for receiving local oscillating signals, and the bases (gates) of said second and said third transistors are coupled together to be AC grounded, wherein the phase shift between said one signal input end and said first signal output end or said second signal output end is determined by the intrinsic resistors of said transistors, said inductor and said capacitor.