| 摘要 |
A detection logic (10) which is responsive to the phase difference between the two input signals (REFIN, VCOIN) of the comparator provides two detection signals (U, D) to control a charge pump (22) through a control logic (120). The control logic (120) combines the detection signals (U, D) with two pulse signals, one of them (PR) presenting an active impulse of fixed length after each active front of the first input signal (REFIN), the other (PV) presenting an active impulse of fixed length after each active front of the second input signal (VCOIN). For small phase differences, the active impulses of the pulsed signals (PR, PV) present an overlap, and the control logic (120) controls the charge pump (22) as a function of a separation signal (W) which changes status with a fixed delay with respect to the active front of one of DOLLAR he input signals (VCOIN). Thereby, the dead zone of conventional phase comparators due to very short or too short activation of detection signals (U, D) is eliminated.
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