Systems and methods for narrowband signal quadrature error correction

Patent metadata

Field	Value
Publication number	US-9306782-B2
Application number	US-201514657029-A
Country	US
Kind code	B2
Filing date	Mar 13, 2015
Priority date	Apr 7, 2014
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

Apparatus and method for quadrature error correction for narrowband or tone signal are disclosed. An analog circuit receives a modulated signal and processes in-phase signal and quadrature-phase signal in in-phase and quadrature-phase signal paths respectively. A digital signal processor performs discrete Fourier transform on each of the in-phase and quadrature-phase signals and determines statistical parameters responsive to mismatch characteristics to estimate quadrature error correction.

First claim

What is claimed is:

1. An apparatus for processing a modulated signal, the apparatus comprising:
a quadrature demodulator configured to receive the modulated signal and generate an in-phase signal for a first signal path and a quadrature-phase signal for a second signal path; and
one or more signal processors configured to:
perform discrete Fourier transform to generate one or more frequency domain values based on the in-phase signal from the first path and the quadrature-phase signal from the second path;
determine a plurality of statistical parameters responsive to one or more mismatch characteristics between the in-phase signal and the quadrature-phase signal based at least partly on the one or more frequency domain values;
determine the one or more mismatch characteristics based on the plurality of statistical parameters; and
reduce quadrature error based on the one or more mismatch characteristics,

wherein the plurality of statistical parameters include one or more expected values indicating relationships between one or more positive and negative frequency components of the in-phase signal and the quadrature-phase signal.

2. The apparatus in claim 1 , wherein the modulated signal is a narrowband signal or a tone signal.

3. The apparatus in claim 2 , wherein the modulated signal is a tone signal and the one or more signal processors are further configured to generate parameters for reduction of quadrature error in a deterministic manner based at least partly on observations of frequency components of the in-phase signal and the quadrature-phase signal.

4. The apparatus in claim 1 , wherein the one or more signal processors are configured to reduce quadrature error by modifying the in-phase signal and/or the quadrature-phase signal to generate a modified in-phase signal and/or a modified quadrature-phase signal.

5. The apparatus in claim 1 , wherein the one or more mismatch characteristics include at least one of a phase mismatch and an amplitude mismatch.

6. The apparatus in claim 5 , wherein determining of the one or more mismatch characteristics comprises approximating the one or more mismatch characteristics.

7. The apparatus in claim 6 , wherein approximating comprises linear approximation.

8. The apparatus in claim 1 , wherein the one or more processors are configured to generate the one or more frequency domain values based on Goertzel Algorithm processing.

9. The apparatus in claim 1 comprising a bandpass filter having a bandwidth in which a channel mismatch is treated as a constant for analysis.

10. The apparatus in claim 1 , wherein the one or more mismatch characteristics comprises:
a gain mismatch A determined according to

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a phase mismatch φ determined according to

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Assignees

• Analog Devices Inc

Inventors

• An Wei
• Stein Yosef

Classifications

• H04L7/0079

  Receiver details · CPC title

• H04L27/2276 Primary

  using frequency multiplication or harmonic tracking · CPC title

• H03D3/009

  Compensating quadrature phase or amplitude imbalances · CPC title

• H04L27/3863

  Compensation for quadrature error in the received signal · CPC title

• H04L27/2631 Primary

  with polyphase implementation · CPC title