Patent ID: 7346128
Filing Date: 2008-03-18
Classification: H04B

Abstract:
1. A dual-mode receiver, comprising: an antenna for receiving an input signal with a carrier from a transmitting channel; a low noise amplifier coupled to the antenna, for amplifying the input signal; a quadrature mixer coupled to the low noise amplifier, for receiving an amplified signal and two local oscillator signals respectively with a first phase and a second phase, wherein when the dual-mode receiver operates in a direct-conversion mode, the quadrature mixer converts the amplified signal down to a pair of first baseband signals and when the dual-mode receiver operates in a low-IF mode, the quadrature mixer converts the amplified signal down to a pair of second intermediate frequency signals with the carrier whose frequency is a first frequency; a pair of dual-mode filters coupled to the mixer, wherein when the dual-mode receiver operates in the direct-conversion mode, the dual-modes filters are a pair of low pass filters and when the dual-mode receiver operates in the low-IF mode, the dual-modes filters are a pair of poly-phase filters; a pair of programmable gain amplifiers respectively coupled to the dual-mode filters, wherein when the dual-mode receiver operates in the direct-conversion mode, the programmable gain amplifiers receive first baseband signals to generate a pair of first signals output and when the dual-mode receiver operates in the low-IF mode, the programmable gain amplifiers receive the second intermediate frequency signal signals to generate a pair of second signals output; a secondary downconverter, wherein when the dual-mode receiver operates in the low-IF mode, the secondary downconverter receives the second signals and a second local oscillator signal, and converts the second signals to a pair of third baseband signals output; and a pair of switching elements for connecting the programmable gain amplifiers to the secondary downconverter when the dual-mode receiver operates in the low-IF mode.