AN RF FRONT-END WITH A MULTISTAGE STEPDOWN FILTERING ARCHITECTURE

摘要

A radio-frequency (RF) front-end comprises a low noise amplifier LNA (105), a first mixer (106) and an I/Q quadrature mixer (108). The LNA amplifies a received signal at a carrier frequency, the LNA having inductive loads (112). The first mixer, coupled to the LNA, mixes an amplified received signal with a first local oscillator (LO) signal to down convert the amplified signal to an intermediate frequency (IF). The first mixer has inductive loads (113). The first frequency is related to the carrier frequency such that an image channel associated with the carrier and the LO frequency is outside the bandwidth of the inductive loads of the LNA. The I/Q quadrature mixer stage has a second mixer (108A) and a third mixer (108B) coupled to the first mixer. The I/Q quadrature mixer converts the IF signal to I and Q signals using a second LO signal related to the first LO signal.