Patent ID: 6097768
Filing Date: 2000-08-01
Classification: H03L,H04B,H04L

Abstract:
A phase detector for detecting a phase difference between a transmitter oscillator and a receiver oscillator in a differential quadriphase-shift-keying communications system, the phase detector comprising:a first mixer that receives a received signal, wherein said received signal includes a frequency and phase generated by said transmitter oscillator, and wherein said first mixer multiplies said received signal with an in-phase signal of said receiver oscillator, and wherein said first mixer generates a first mixer output;a second mixer that receives said received signal, wherein said second mixer multiplies said received signal with a quadrature-phase signal of said receiver oscillator, and wherein said second mixer generates a second mixer output;a first sampling unit coupled to receive said first mixer output, wherein said first sampling unit produces a first digital signal comprising a sign and a magnitude, and wherein said first digital signal represents an in-phase component of said received signal in response to said first mixer output;a second sampling unit coupled to receive said second mixer output, wherein said second sampling unit produces a second digital signal comprising a sign and a magnitude, and wherein said second digital signal represents a quadrature-phase component of said received signal in response to said second mixer output; anda logic unit coupled to said first sampling unit and to said second sampling unit wherein said logic unit receives said first and second digital signals, wherein said logic unit operates to calculate a phase-error signal that represents said phase difference between said transmitter oscillator and said receiver oscillator, and wherein said logic unit detects the difference between the magnitudes of said first and second digital signals in calculating the phase error signal.