CONSTANT-CURRENT TYPE CHARGE PUMP CIRCUIT FOR PHASE SYNCHRONIZATION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a constant-current type charge pump circuit that is less affected by dispersion in a resistance of an IC to be constituted. ;SOLUTION: A constant-current type charge pump circuit used for a phase synchronization circuit is configured, such that a current flows-in from a loop filter with a charge-down signal from a phase comparator and the current flows-out to the loop filter with a charge-up signal. A single constant current source circuit is configured such that a current supplied from a constant voltage power supply Vcc is conducted at all times by a transistor(TR) Q₃ dividing resistors R₁, R₄, has TRs Q₄, Q₁₅ being as two current mirror circuits to the TR Q₃, the one of the current mirror circuit makes the charge-down signal the operating signal, and the other current mirror circuit makes the charge-up signal the operating signal.;COPYRIGHT: (C)1998,JPO