The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 18, 1996
Filed:
May. 09, 1995
Cheng-Youn Lu, Cresskill, NJ (US);
Robert S Burroughs, Doylestown, PA (US);
Panasonic Technologies, Inc., , US;
Abstract
A quadrature demodulator for demodulating an input signal which includes respective data signals modulating in-phase and quadrature carriers. The demodulator includes a voltage controlled oscillator responsive to a control signal for generating an oscillatory signal. A demodulator, coupled to receive the oscillatory signal from the voltage controlled oscillator and the input signal, provides the in-phase and quadrature components of the input signal. Phase comparison circuitry, responsive to the in-phase and quadrature components of the input signal generates a phase error signal. The phase error signal represents the difference, in phase and magnitude, between a vector defined by the in-phase and quadrature components of the input signal and reference vectors. Filter circuitry, responsive to the phase error signal, generates a control signal for the voltage controlled oscillator. Phase error correction circuitry selectively applies the error signal to the filter circuitry when the magnitude of a vector defined by the in-phase and quadrature components of the input signal exceeds a first threshold. Another embodiment provides the phase error signal to the filter circuitry when the magnitude of a vector defined by the in-phase and quadrature components of the input signal either exceeds a first threshold or is less than a second threshold.