Receiver capable of receiving analog broadcast and digital broadcast and IC for the same

A receiver for receiving an analog broadcast and a digital broadcast, comprising:

• a first mixer circuit and a second mixer circuit for performing a frequency conversion of a received signal using a local oscillation signal to generate an in-phase intermediate frequency signal and a quadrature intermediate frequency signal, respectively, wherein phases of in-phase and quadrature intermediate frequency signals are orthogonal to each other;
• a first filter circuit and a second filter circuit for taking out the in-phase intermediate frequency signal and the quadrature intermediate frequency signal from output signals of said first mixer circuit and said second mixer circuit, respectively;
• an in-phase circuit for taking out DC offset voltages of said in-phase intermediate frequency signal from said in-phase intermediate frequency signal at the time of receiving said digital broadcast;
• an in-phase circuit for correcting DC offsets of said in-phase intermediate frequency signal by using the taken out in-phase DC offset voltage;
• a quadrature circuit for taking out DC offset voltages of said quadrature intermediate frequency signal from said quadrature intermediate frequency signal at the time of receiving said digital broadcast;
• a quadrature circuit for correcting DC offsets of said quadrature intermediate frequency signal by using the taken out quadrature DC offset voltage;
• and,
• a demodulation circuit for taking out a signal indicating broadcast contents in one of the analog broadcast and the digital broadcast from the in-phase intermediate frequency signal and the quadrature intermediate frequency signal taken out by said first filter circuit and said second filter circuit, wherein:
• a frequency of the local oscillation signal is separated from a carrier frequency of the received signal by an intermediate frequency of the in-phase intermediate frequency signal and the quadrature intermediate frequency signal and said demodulation circuit takes out the signal indicating broadcast contents in the analog broadcast from the in-phase intermediate frequency signal and the quadrature intermediate frequency signal, at a time of receiving the analog broadcast, and
• the frequency of the local oscillation signal is equal to a center frequency of the received signal and said demodulation circuit takes out the signal indicating broadcast contents in the digital broadcast from the in-phase intermediate frequency signal and the quadrature intermediate frequency signal, at a time of receiving the digital broadcast.

An IC for receiving an analog broadcast and a digital broadcast, comprising:

• a mixer circuit for performing frequency conversion of a received signal to an intermediate frequency signal by means of a local oscillation signal;
• a filter circuit for taking out the intermediate frequency signal from an output signal of said mixer circuit;
• a first circuit for taking out a DC offset voltage of said intermediate frequency signal from said intermediate frequency signal at the time of receiving said digital broadcast;
• and,
• a second circuit for correcting the DC offset of said intermediate frequency signal by using the taken out DC offset voltage, wherein:
• a frequency of the local oscillation signal is separated from a carrier frequency of the received signal by an intermediate frequency of the intermediate frequency signal at a time of receiving the analog broadcast, and the frequency of the local oscillation signal is equal to a center frequency of the received signal at a time of receiving the digital broadcast, and
• a signal indicating broadcast contents in one of the analog broadcast and digital broadcast is taken out of the intermediate frequency signal taken out by said filter circuit.

An IC for receiving an analog broadcast and a digital broadcast, comprising:

• a first mixer circuit and a second mixer circuit for performing a frequency conversion of a received signal using a local oscillation signal to generate an in-phase intermediate frequency signal and a quadrature intermediate frequency signal, respectively, wherein phases of in-phase and quadrature intermediate frequency signals are orthogonal to each other;
• a first filter circuit and a second filter circuit for taking out the in-phase intermediate frequency signal and the quadrature intermediate frequency signal from output signals of said first mixer circuit and said second mixer circuit, respectively;
• an in-phase circuit for taking out DC offset voltages of said in-phase intermediate frequency signal from said in-phase intermediate frequency signal at the time of receiving said digital broadcast;
• an in-phase circuit for correcting DC offsets of said in-phase intermediate frequency signal by using the taken out in-phase DC offset voltage;
• a quadrature circuit for taking out DC offset voltages of said quadrature intermediate frequency signal from said quadrature intermediate frequency signal at the time of receiving said digital broadcast;
• and
• a quadrature circuit for correcting DC offsets of said quadrature intermediate frequency signal by using the taken out quadrature DC offset voltage, wherein:
• a frequency of the local oscillation signal is separated from a carrier frequency of the received signal by an intermediate frequency of the in phase intermediate frequency signal and the quadrature intermediate frequency signal, at a time of receiving the analog broadcast, and the frequency of the local oscillation signal is equal to a center frequency of the received signal, at a time of receiving the digital broadcast, and
• a signal indicating broadcast contents in one of the analog broadcast and the digital broadcast is taken out of the in-phase intermediate frequency signal and the quadrature intermediate frequency signal taken out by said first filter circuit and said second filter circuit.