Correcting for phase noise of an oscillator
First Claim
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1. An apparatus comprising:
- a phase-to-digital converter (PDC) to receive a local oscillator (LO) signal and to determine a digital phase noise value corresponding to a measure of phase noise present in the LO signal, the PDC comprising;
a counter to receive the LO signal, the counter controlled by a reference clock, wherein the counter is to generate a count of LO signal cycles during a cycle of the reference clock;
a first storage coupled to the counter to store the count;
a delay line coupled to receive the LO signal, the delay line having L stages each to provide an output;
a second storage coupled to receive the L outputs and to provide a value of the L outputs responsive to the reference clock;
a decoder coupled to the second storage to receive the values and generate a decoder output corresponding to a number of partial LO cycles during the reference clock cycle; and
a first mixer to receive an intermediate frequency (IF) signal obtained from a received radio frequency (RF) signal and remove phase noise from the IF signal using the digital phase noise value.
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Abstract
In one embodiment, the present invention includes a method for digitizing a phase noise value indicative of a level of phase noise present in a LO signal and downconverting an RF signal to a second frequency signal using the LO signal. This downconversion can cause the phase noise to be transferred to the second frequency signal. The method may thus further include removing the phase noise from the second frequency signal using the digitized phase noise value.
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22 Claims
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1. An apparatus comprising:
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a phase-to-digital converter (PDC) to receive a local oscillator (LO) signal and to determine a digital phase noise value corresponding to a measure of phase noise present in the LO signal, the PDC comprising; a counter to receive the LO signal, the counter controlled by a reference clock, wherein the counter is to generate a count of LO signal cycles during a cycle of the reference clock; a first storage coupled to the counter to store the count; a delay line coupled to receive the LO signal, the delay line having L stages each to provide an output; a second storage coupled to receive the L outputs and to provide a value of the L outputs responsive to the reference clock; a decoder coupled to the second storage to receive the values and generate a decoder output corresponding to a number of partial LO cycles during the reference clock cycle; and a first mixer to receive an intermediate frequency (IF) signal obtained from a received radio frequency (RF) signal and remove phase noise from the IF signal using the digital phase noise value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method comprising:
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digitizing a phase noise value indicative of a level of phase noise present in a local oscillator (LO) signal, including generating a count of LO signal cycles during a cycle of a reference clock, storing the count, receiving the LO signal in a delay line, the delay line having L stages each to provide an output, providing a value of the L outputs responsive to the reference clock, and generating from the value an output corresponding to a number of partial LO cycles during the reference clock cycle; downconverting an incoming radio frequency (RF) signal to a second frequency signal using the LO signal, wherein the downconverting causes the phase noise to be transferred to the second frequency signal; and removing the phase noise from the second frequency signal using the digitized phase noise value. - View Dependent Claims (10, 11, 12, 13, 14)
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15. An apparatus comprising:
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a digitally controlled oscillator (DCO) to generate a local oscillator (LO) signal; phase digitization means coupled to the DCO for receiving a LO signal and determining a phase noise present in the LO signal, wherein the phase digitization means comprises a counter to receive the LO signal, the counter controlled by a reference clock and to generate a first portion of a digital word corresponding to a count of LO signal cycles during a cycle of the reference clock, a delay line coupled to receive the LO signal, the delay line having L stages each to provide an output, and a decoder coupled to the delay line to receive the L outputs responsive to the reference clock and generate a second portion of the digital word corresponding to a number of partial LO cycles during the reference clock cycle; a front end mixer to receive a radio frequency (RF) signal and downconvert the RF signal to an intermediate frequency (IF) using the LO signal, wherein the phase noise is transferred to the IF signal; and a downstream mixer coupled to the front end mixer to receive the IF signal, a second LO signal and the determined phase noise and to downconvert the IF signal including the phase noise to a baseband signal without the phase noise. - View Dependent Claims (16, 17, 18)
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19. A system comprising:
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a tuner to receive a radio frequency (RF) signal from a signal source and downconvert the RF signal to a baseband frequency to extract a signal channel from the RF signal, the tuner including a phase-to-digital converter (PDC) to receive a local oscillator (LO) signal used in the downconversion and to determine a digital phase noise value corresponding to a measure of phase noise present in the LO signal, and a downstream mixer to receive a first downconverted signal and remove phase noise therefrom using the digital phase noise value, wherein the PDC comprises a counter to receive the LO signal, the counter controlled by a reference clock, wherein the counter is to generate a count of LO signal cycles during a cycle of the reference clock, a first storage coupled to the counter to store the count, a delay line coupled to receive the LO signal, the delay line having L stages each to provide an output, a second storage coupled to receive the L outputs and to provide a value of the L outputs responsive to the reference clock, and a decoder coupled to the second storage to receive the values and generate a decoder output corresponding to a number of partial LO cycles during the reference clock cycle; a demodulator coupled to the tuner to demodulate the signal channel and to generate a transport stream therefrom; and a processor coupled to the demodulator to receive the transport stream and to process the transport stream to obtain audio visual data. - View Dependent Claims (20, 21, 22)
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Specification