Circuit and method for converting a radio frequency signal into a baseband signal

A circuit for producing a baseband signal from a tuned radio frequency signal, said circuit comprising:

• means for providing a specific frequency signal, comprising an identical frequency and an identical phase of the tuned radio frequency signal, in response to a phase-locked signal and a control voltage, said means for providing comprising:
• voltage controlled oscillating means for producing the specific frequency signal in response to the control voltage and the phase-locked signal;
• and
• phase comparing means for providing the control voltage by comparing the phase of the tuned radio frequency signal with the phase of the specific frequency signal;
• and
• means for producing the baseband signal by mixing the specific frequency signal and the tuned radio frequency signal.

A broadcast signal receiving apparatus producing a baseband signal having a same phase and frequency as a radio frequency signal, said apparatus comprising:

• receiving means for providing a tuned radio frequency signal by tuning the radio frequency signal, said receiving means comprising:
• a tuner comprising a first input terminal for receiving the radio frequency signal, and an output terminal providing the tuned radio frequency signal;
• and
• a phase-locked loop comprising an input terminal for receiving the tuned radio frequency signal, a first output terminal for providing a first phase-locked signal to the tuner, a second output terminal for providing a second phase-locked signal to the tuner and a third output terminal for providing a third phase-locked signal;
• and
• output means for producing the baseband signal, said output means comprising:
• a baseband circuit converting the tuned radio frequency signal into a baseband signal;
• a gain control circuit comprising an input terminal for receiving the baseband signal, a first output terminal for providing a gain control signal to a second input terminal of the baseband circuit, and a second output terminal for providing said gain control signal being delayed to a second input terminal of the tuner;
• and
• a frequency oscillating circuit comprising a first input terminal for receiving the tuned radio frequency signal, a second input terminal for receiving the third phase-locked signal, and an output terminal for providing the specific frequency signal to a third input terminal of the baseband circuit.

A broadcast signal direct-receiving circuit comprising:

• receiving means for providing a tuned radio frequency signal by tuning a radio frequency signal, said receiving means comprising:
• tuning means for producing said tuned radio frequency signal, said tuning means frequency signal, said receiving means comprising:
• tuning means for producing said tuned radio frequency signal, said tuning means comprising an input tuner with a first input terminal for receiving the radio frequency signal and an output terminal for providing an input tuner signal, a first amplifier with a first input terminal for receiving the input tuner signal and an output terminal for providing a first amplified signal, and an interstage tuner with a first input terminal for receiving the first amplified signal and an output terminal for providing the tuned radio frequency signal;
• and
• phase-locked loop means comprising an input terminal for receiving the tuned radio frequency signal, a first output terminal for providing a first phase-locked signal to a second input terminal of the input tuner, a second output terminal for providing a second phase-locked signal to a second input terminal of the interstage tuner, and a third output terminal for providing a third phase-locked signal;
• and
• output means for producing a baseband signal in response to the tuned radio frequency signal and the third phase-locked signal, said output means comprising:
• a baseband circuit comprising a mixer with a first input terminal for receiving the tuned radio frequency signal and an output terminal for providing a mixed signal, a first filter with an input terminal for receiving the mixed signal and an output terminal for providing a first filtered signal, and a second amplifier having a first input terminal for receiving the first filtered signal and an output terminal for providing the baseband signal;
• a gain control circuit comprising an automatic gain control section and a delay section, said automatic gain control section having an input terminal for receiving the baseband signal and an output terminal for providing an automatic gain control signal to a second input terminal of the second amplifier, said delay section having an input terminal for receiving the automatic gain control signal and an output terminal for providing said automatic gain control signal being delayed to a second input terminal of the first amplifier;
• and
• a frequency oscillating circuit comprising:
• a voltage controlled oscillator having a first input terminal for receiving the third phase-locked signal, a second input terminal for receiving a control voltage and an output terminal for providing a specific frequency signal to a second input terminal of the mixer;
• a phase comparator having a first input terminal for receiving the specific frequency signal, a second input terminal for receiving the tuned radio frequency signal and an output terminal for providing a phase-compared signal;
• a second filter having an input terminal for receiving the phase-compared signal and an output terminal for providing a second filtered signal;
• and
• a third amplifier having an input terminal receiving the second filtered signal and an output terminal for providing the control voltage to a second input terminal of the voltage controlled oscillator.

A broadcast signal receiving apparatus for producing a baseband signal having a same phase and frequency as a tuned radio frequency signal, said apparatus comprising:

• a phase-locked loop providing a phase-locked signal in dependence upon the tuned radio frequency signal;
• means for producing a specific frequency signal, comprising a same frequency and phase of the tuned radio frequency, in response to the tuned radio frequency signal and said phase-locked signal, said means for producing comprising:
• voltage controlled oscillating means for providing the specific frequency signal in response to the phase-locked signal and a control voltage;
• and
• phase comparing means for providing the control voltage by comparing the phase of the tuned radio frequency signal and the phase of the specific frequency signal;
• and
• means for producing the baseband signal by mixing the specific frequency signal with the tuned radio frequency signal.

A circuit for producing a baseband signal from a tuned radio frequency signal, said circuit comprising:

• a phase-locked loop providing a phase-locked signal in dependence upon the tuned radio frequency signal;
• means for producing a specific frequency signal in response to said phase-locked loop signal and in response to a phase comparison of the tuned radio frequency signal and the specific frequency signal;
• and
• means for producing the baseband signal by mixing the specific frequency signal with the tuned radio frequency signal.

A method of converting a radio frequency signal into a baseband signal, said method comprising the steps of:

• providing a tuned radio frequency signal by tuning the radio frequency signal in accordance with a phase-locked signal of a phase-locked loop;
• generating a specific frequency signal corresponding in phase and frequency to the tuned radio frequency signal, in response to the phase-locked signal and a control voltage, and providing said control voltage by comparing the phase of the tuned radio frequency signal with the phase of the phase-locked signal;
• and
• producing the baseband signal by mixing the specific frequency signal and the tuned radio frequency signal.

A method of producing a baseband signal from a tuned radio frequency signal, said method comprising the steps of:

• generating a phase-locked signal of the tuned radio frequency signal;
• providing a control voltage corresponding to a comparison of a phase of the tuned radio frequency signal and a phase of a specific frequency signal;
• producing the specific frequency signal comprising a same phase and frequency as the tuned radio frequency signal in response to the phase-locked signal and the control voltage;
• and
• producing the baseband signal by mixing the specific frequency signal with the tuned radio frequency signal.

A method of converting a radio frequency signal to a baseband signal, said method comprising the steps of:

• tuning said radio frequency signal in response to a gain control signal being delayed;
• producing a phase-locked signal in response to the tuned radio frequency signal;
• producing a control signal by comparing a phase of a specific frequency signal with a phase of the tuned radio frequency signal;
• producing the specific frequency signal in a voltage controlled oscillator in response to the phase-locked signal and the control signal;
• and
• producing the baseband signal by mixing the specific frequency signal with the tuned radio frequency signal and controlling a gain of the baseband signal according to the gain control signal.