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US 8,503,576 B2Granted
Mirror signal IQ-imbalance correction
AssigneeSiTune Corporation
InventorsSaeid Mehrmanesh, Vahid Mesgarpour Toosi, Mahdi Khoshgard
Life of this patent
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Abstract
A system and method are provided for calibrating the IQ-imbalance in a low-IF receiver. A Test Signal can be generated in a mirror frequency and conveyed to the receiver. The power of the signal produced in the receiver from the conveyed Test Signal can be measured. In the absence of an IQ-imbalance, the Test Signal can be completely eliminated in the receiver and the corresponding measured power of the produced signal can be minimized. Accordingly, a two dimensional algorithm is described for calibrating a receiver and correcting the IQ-imbalance by adjusting the phase and gain difference between the I and Q channels in the receiver based on the measured power of the signal produced in the receiver.
Claims16
A system comprising:
- a low-IF receiver configured to be tunable for selected channels;
- a synthesizer configured to produce a Test Signal in mirror frequencies for a selected channel and for conveying the Test Signal to the receiver;
- and
- an IQ Imbalance Estimator configured for estimating a phase imbalance and a gain imbalance in the receiver based on a signal produced in the receiver from the Test Signal;
- wherein the system is further configured for:
- setting a first searching region for gain imbalance and phase imbalance in the receiver, wherein the first searching region is a two-dimensional space defined by gain imbalance values on a gain axis and phase imbalance values on a phase axis;
- selecting a first plurality of grid-points within the first searching region;
- and
- measuring a Power Estimate for each grid-point in the first plurality of grid-points by setting a gain-correction and a phase-correction in the receiver corresponding to the coordinates of each grid-point in the first plurality of grid-points and measuring the Power Estimate of the signal produced in the receiver from the conveyed mirror-frequency signal for each grid-point in the first plurality of grid-points.
6 more elements
A method comprising:
- selecting a channel in a low-IF receiver;
- producing a Test Signal in minor frequencies for the selected channel;
- conveying the Test Signal to the receiver;
- estimating a phase imbalance and a gain imbalance in the receiver based on a signal produced in the receiver from the Test Signal;
- selecting a first set of combinations of phase imbalance values and gain imbalance values;
- measuring a Power Estimate for each combination in the first set of combinations of phase imbalance values and gain imbalance values;
- selecting a first ideal combination in the first set of combinations, where the first ideal combination is a combination producing the lowest Power Estimate in the first set of combinations;
- selecting a second set of combinations of phase imbalance values and gain imbalance values, wherein the second set of combinations is based on the first ideal combination;
- measuring a Power Estimate for each combination in the second set of combinations of phase imbalance values and gain imbalance values;
- selecting a second ideal combination in the second set of combinations, where the second ideal combination is a combination producing the lowest Power Estimate in the second set of combinations.
7 more elements
A method comprising:
- selecting a channel in a low-IF receiver;
- producing a Test Signal in minor frequencies for the selected channel;
- conveying the Test Signal to the receiver;
- estimating a phase imbalance and a gain imbalance in the receiver based on a signal produced in the receiver from the Test Signal;
- setting a first searching region for gain imbalance and phase imbalance in the receiver, wherein the first searching region is a two-dimensional space defined by gain imbalance values on a in axis and phase imbalance values on a phase axis;
- selecting a first plurality of grid-points within the first searching region;
- and
- measuring a Power Estimate for each grid-point in the first plurality of grid-points by setting a gain-correction and a phase-correction in the receiver corresponding to the coordinates of each grid-point in the first plurality of grid-points and measuring the Power Estimate of the signal produced in the receiver from the conveyed minor-frequency signal for each grid-point in the first plurality of grid-points.
5 more elements
An apparatus comprising:
- a low-IF receiver configured to be tunable for selected channels;
- a synthesizer configured to produce a Test Signal in mirror frequencies for a selected channel and for conveying the Test Signal to the receiver;
- a power detector configured to produce a Power Estimate of the signal produced in the receiver from the conveyed Test Signal;
- an IQ Imbalance Estimator configured for estimating a phase imbalance and a gain imbalance in the receiver based on the Power Estimate;
- and,
- an IQ Imbalance Compensator configured for adjusting the difference in the gain and the phase between the I channel and the Q channel in the receiver based on the estimated gain imbalance and the estimated phase imbalance;
- wherein the apparatus is further configured for:
- setting a first searching region for gain imbalance and phase imbalance in the receiver, wherein the first searching region is a two-dimensional space defined by gain imbalance values on a gain axis and phase imbalance values on a phase axis;
- selecting a first plurality of grid-points within the first searching region;
- and
- measuring a Power Estimate for each grid-point in the first plurality of grid-points by setting a gain-correction and a phase-correction in the receiver corresponding to the coordinates of each grid-point in the first plurality of grid-points and measuring the Power Estimate of the signal produced in the receiver from the conveyed minor-frequency signal for each grid-point in the first plurality of grid-points.
8 more elements
Dependencies are inferred from the claim text.