| 摘要 |
PURPOSE: There is provided a phase detector inside a carrier frequency recovery circuit of a demodulator, which adds a small number of circuits to control a decision area depending on the intensity of noise and improves bit error rate due to phase shift error. CONSTITUTION: A phase detector inside a carrier frequency recovery circuit of a demodulator includes a phase detection unit(10) for receiving an in-phase component signal and quadrature phase component signal to output an error signal, a shifter(20) for outputting the in-phase component signal as multiple bit-shifted signals, and a first multiplexer(30) for outputting one of the multiple bit-shifted signals. The phase detector also includes a subtracter(40) for subtracting the output signal of the first multiplexer from the quadrature phase component signal, a comparator(50) for receiving the subtracted value and a reference value to compare them with each other, an OR gate(60) for ORing the output signals of the comparator, and a second multiplexer(70) for sending an error signal from the phase detection unit or the reference value to an external loop filter in response to the output signal of the OR gate.
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