Quadrature demodulator

Details Quadrature demodulator Quadrature demodulator

2007-07-30

2009-11-17

Chang, Joseph (Department: 2817)

Demodulators

Phase shift keying or quadrature amplitude demodulator

C329S306000

Reexamination Certificate

active

07619466

ABSTRACT:
A quadrature demodulator includes a reception section which receives a signal transmitted by an RFID tag and containing a specific pattern and data following the specific pattern and multiplies the reception signal by a local signal to generate an I-signal, while multiplying the reception signal by the local signal shifted in phase by 90 degrees to generate a Q-signal, a first demodulating circuit which squares the I- and Q-signals and adding the resulting I- and Q-signals together to generate data on the basis of the addition result, a second demodulating circuit which detects the specific pattern in the I- and Q-signals to decode the data following one of the detected specific patterns, and a control section which selects one of the first and second demodulating circuits in accordance with a gain determined by the result of the addition between the values of the squared I- and Q-signals.

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patent: 7486131 (2009-02-01), Murofushi et al.
patent: 1557962 (2005-07-01), None

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