Patent ID: 7027794
Filing Date: 2006-04-11
Classification: H03D,H04B

Abstract:
1. A radio receiver performing reception control of a radio signal comprising: a radio signal amplifier, a frequency converter, an I-signal generator and a Q-signal generator: wherein the radio signal amplifier amplifies a received radio signal and generates an amplified signal, wherein the frequency converter mixes the amplified signal with a local oscillation signal to thereby convert the radio signal having a radio frequency into a first intermediate frequency signal, and mixes the amplified signal with a local oscillation signal shifted by π/2 by a π/2 phase shifter to thereby convert the radio signal having a radio frequency into a second intermediate frequency signal, wherein the I-signal generator includes a first frequency control part, a first AC coupling part and a first radio signal demodulating part, wherein the first frequency control part, including at least one of a frequency shift controller for shifting the first intermediate frequency signal towards an upper part of a frequency band and a frequency inversion controller for inverting a low-frequency side of the first intermediate frequency signal towards the upper part of the frequency band and inverting a high-frequency side thereof towards a lower part thereof, performs frequency control of the first intermediate frequency signal and avoids loss of energy of low-frequency components of the first intermediate frequency signal due to AC coupling being set at a first high cutoff frequency, wherein the first AC coupling part provided at an output side of the first frequency control part is set at the first high cutoff frequency to suppress DC fluctuation from the first intermediate frequency signal, wherein the first radio signal demodulating part demodulates an output signal obtained via the first AC coupling part and generates an I-signal, wherein the Q-signal generator includes a second frequency control part, a second AC coupling part and a second radio signal demodulating part, wherein the second frequency control part, including at least one of a frequency shift controller for shifting the second intermediate frequency signal towards an upper part of a frequency band and a frequency inversion controller for inverting a low-frequency side of the second intermediate frequency signal towards the upper part of the frequency band and inverting a high-frequency side thereof towards a lower part thereof, performs frequency control of the second intermediate frequency signal and avoids loss of energy of low-frequency components of the second intermediate frequency signal due to AC coupling being set at a second high cutoff frequency, wherein the second AC coupling part provided at an output side of the second frequency control part is set at the second high cutoff frequency to suppress DC fluctuation from the second intermediate frequency signal, and wherein the second radio signal demodulating part demodulates an output signal obtained via the second AC coupling part and generates a Q-signal.