Local oscillator and mixer for a radio frequency receiver and related method
AssigneeSilicon Laboratories Inc.
InventorRichard A. Johnson
Life of this patent
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Abstract
A circuit (100) is adapted for use in a radio frequency receiver and includes a transconductance amplifier (110), a direct digital frequency synthesizer (130), and a digital-to-analog converter (DAC) (120). The transconductance amplifier (110) has an input terminal for receiving a radio frequency signal, and an output terminal for providing a current signal. The direct digital frequency synthesizer (130) has an output terminal for providing a digital local oscillator signal at a selected frequency. The DAC (120) has a first input terminal coupled to the output terminal of the transconductance amplifier (110), a second input terminal coupled to the output terminal of the direct digital frequency synthesizer (130), and an output terminal for providing an output signal.
Claims26
A circuit for use in a radio frequency receiver comprising:
- a transconductance amplifier having an input terminal for receiving a radio frequency signal, and an output terminal for providing a current signal;
- a direct digital frequency synthesizer having an output terminal for providing a digital local oscillator signal at a selected frequency;
- and
- a digital-to-analog converter having a first input terminal coupled to said output terminal of said transconductance amplifier, a second input terminal coupled to said output terminal of said direct digital frequency synthesizer, and an output terminal for providing an output signal.
A mixer for use in a radio frequency tuner having a plurality of cells, each cell coupled to a first output terminal that provides an output signal of the mixer and comprising:
- a current source having first and second terminals, said current source having a size proportional to an order of the cell and generating an output current proportional to a voltage applied at said second terminal;
- means for modulating a voltage at said first terminal of said current source in response to a received voltage signal;
- and
- means for selectively diverting said output current between said first output terminal and a second output terminal in response to a bit of a digital local oscillator signal having an order corresponding to an order of the cell.
A method for use in a radio frequency receiver comprising the steps of:
- receiving a radio frequency signal;
- converting said radio frequency signal into a current signal;
- generating a digital local oscillator signal;
- and
- mixing said current signal with said digital local oscillator signal to form an analog output signal.
A method for use in a radio frequency receiver comprising the steps of:
- receiving a radio frequency signal;
- converting said radio frequency voltage signal into a current signal having a plurality of currents;
- generating a digital local oscillator signal having a predetermined number of bits each corresponding to one of said plurality of currents;
- and
- switching each of said plurality of currents selectively based on a logic state of a corresponding bit of said digital local oscillator signal to form an analog output signal.
Dependencies are inferred from the claim text.