| 摘要 |
PURPOSE:To realize a wide frequency pull-in range decided by only the variable frequency range of a VCO by compensating frequency fluctuation by detecting a frequency error signal by using convergence signals at two points, and controlling the VCO by a signal to which micro offset is supplied. CONSTITUTION:A sampler 2 receives a signal outputted from a complex multiplier 1, and samples the signal by a clock of four times a modulation clock, and outputs samples S(T/4) 101, S(3T/4) 102, and S(T/2) 103. A filter 4 is provided with the same characteristic as that of a filter 3, and a filter 6 is provided with the same characteristic as that of a filter 5 for the real and false parts of the sample S(T/4) 101, and performs equalization so as to eliminate inter-code interference on the real and false parts of the sample S(3T/4) 102. An adder 12 received the signal outputted from a subtractor 11, and supplies the micro offset >=v to the signal, and a loop filter 13 averages the signal, and the VCO 14 outputs an output signal to the complex multiplier 1 as a compensation signal to compensate the frequency fluctuation. Thereby, it is possible to realize the side frequency pull-in range decided by only the variable frequency range of the VCO. |
