发明公开
EP0085615A3 Phase-locked loop circuit 失效
相位锁定环路

Phase-locked loop circuit
摘要:
A phase-locked loop circuit comprises a voltage-controlled oscillator, a phase comparator, a low-pass filter (15), a plurality of pump circuits (14S, 14F, ... ), and a selecting circuit (G 45 ) for selecting one of the pump circuits. The low-pass filter is comprised of a capacitor (C) and a plurality of resistors (R 1 , R 2 ) each connected to one of the pump circuits. By selecting one of the pump circuits to connect to a corresponding resistor, the cutoff frequency or time constant of the low-pass filter is switched in multi-steps.
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