Method and apparatus for calibrating the sideband rejection of a receiver
First Claim
Patent Images
1. A method of calibrating a receiver, the method comprising:
- coupling a tone to a receive signal path;
frequency converting the tone to in-phase (I) and quadrature (Q) signals;
frequency converting the I and Q signals to an intermediate frequency (IF) signal having a sideband attributable to an I/Q imbalance;
frequency converting the I and Q signals to an auxiliary IF signal having a sideband that is complementary to the sideband of the IF signal;
mixing the IF signal with the auxiliary IF signal to produce a baseband signal; and
adjusting at least one of an amplitude or a phase of at least one of the I and Q signals based on the baseband signal.
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Abstract
Methods and apparatus for calibrating In-phase and Quadrature imbalance within a receiver are described. A calibration process can inject a calibration tone to an RF or IF portion of a receiver. The receiver can frequency translate the tone to distinct I and Q calibration signals. The receiver upconverts the I and Q calibration signals to complementary sidebands or images using distinct and substantially matched upconverters. The complementary sidebands are mixed together to generate an error signal. The receiver determines a phase and amplitude correction based on the error signal.
31 Citations
21 Claims
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1. A method of calibrating a receiver, the method comprising:
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coupling a tone to a receive signal path; frequency converting the tone to in-phase (I) and quadrature (Q) signals; frequency converting the I and Q signals to an intermediate frequency (IF) signal having a sideband attributable to an I/Q imbalance; frequency converting the I and Q signals to an auxiliary IF signal having a sideband that is complementary to the sideband of the IF signal; mixing the IF signal with the auxiliary IF signal to produce a baseband signal; and adjusting at least one of an amplitude or a phase of at least one of the I and Q signals based on the baseband signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of calibrating a receiver;
- the method comprising;
determining a calibration event based on a channel selection from one of a plurality of channels in a received wide band signal; deselecting the received wideband signal from a receive signal path; coupling a tone to the receive signal path; frequency converting the tone to a baseband in-phase (I) signal and a baseband quadrature (Q) signal; frequency converting the I signal and the Q signal using an intermediate frequency (IF) local oscillator (LO) signal to an IF signal having a sideband attributable to an I/Q imbalance; frequency converting the I and Q signals using the IF LO signal to an auxiliary IF signal, wherein a phase of the auxiliary IF signal relative to the IF signal is controlled to one of a plurality of predetermined phases; mixing the IF signal with the auxiliary IF signal to produce a baseband signal; and adjusting for at least one of a phase or amplitude imbalance in the I signal and the Q signal based on the baseband signal.
- the method comprising;
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16. An apparatus for calibrating a receiver, the apparatus comprising:
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a tone generator; a multiplexer having a first input coupled to a receive signal path and a second input coupled to the tone generator, and controlled to select one of the receive signal path or the tone generator; an in-phase (I)/quadrature (Q) downconverter coupled to the multiplexer and configured to downconvert a signal output from the multiplexer to an I signal and a Q signal; a balance module coupled to the I/Q downconverter and configured to adjust a phase of the I signal relative to the Q signal based on a phase control signal; an intermediate frequency (IF) local oscillator (LO); an upconverter coupled to the balance module and the IF LO and configured to upconvert the I signal and the Q signal to an IF signal; an auxiliary upconverter coupled to the balance module and the IF LO and configured to upconvert the I signal and the Q signal to an auxiliary IF signal having a phase relative to the phase of the IF signal selected from a plurality of predetermined phases; and an I/Q calibration module configured to mix the IF signal with the auxiliary IF signal to generate a baseband signal, and further configured to determine a value of the phase control signal based at least in part on the baseband signal. - View Dependent Claims (17, 18, 19, 20)
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21. An apparatus for calibrating a receiver, the apparatus comprising:
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means for generating a tone; means for selecting one of an output from the means for generating the tone or a signal; means for converting an output signal from the means for selecting to an in-phase (I) signal and a quadrature (Q) signal; means for adjusting an amplitude and a phase of the I signal and the Q signal; means for upconverting the I signal and the Q signal to an intermediate frequency (IF) signal; means for upconverting the I signal and the Q signal to an auxiliary IF signal having a sideband that is complementary to a sideband of the IF signal; means for mixing the IF signal with the auxiliary IF signal to produce a baseband signal; and means for determining a control signal based on the baseband signal, wherein the control signal is coupled to the means for adjusting and controls the means for adjusting.
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Specification