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I/Q demodulation circuit

  • US 20050041759A1
  • Filed: 08/17/2004
  • Published: 02/24/2005
  • Est. Priority Date: 08/18/2003
  • Status: Active Grant
First Claim
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1. An I/Q demodulation circuit comprising:

  • an I/Q demodulator for producing an analog I/Q signal by multiplying an input signal by a local oscillation signal;

    an analog-to-digital converter for converting the analog I/Q signal into a digital I/Q signal;

    a reference sinusoidal-wave signal generator for producing a predetermined reference sinusoidal-wave signal;

    a selector for selecting and feeding to the I/Q demodulator one of an external input signal and the reference sinusoidal-wave signal;

    an offset amount detection circuit for detecting a DC offset amount and a phase offset amount of the digital I/Q signal obtained when the reference sinusoidal-wave signal is selected;

    a storage circuit for storing a result of detection by the offset amount detection circuit or a correction value with which to correct for the result; and

    an offset correction circuit for correcting for, based on data stored in the storage circuit, a DC offset and a phase offset of the digital I/Q signal obtained when the external input signal is selected.

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