Mstar Semiconductor, Inc.

Walter H Prada

Ryan Lee Bunch

A charge pump phase-locked loop circuit includes an active loop filter, an adjustable reference voltage source, and a charge pump. The active loop filter includes an amplifier that has a negative input node, a positive input node, and an output node. The adjustable reference voltage source is coupled to the positive input node to provide an adjustable reference voltage. The charge pump is coupled to the negative input node to provide a current to or draw a current from the active loop filter in response to a signal from a phase detector. The charge pump includes a first current source coupled to a first voltage and a second current source electrically coupled to a second voltage, the second current source including a resistor. The second current source is configured such that a current provided by the second current source depends on a resistance value of the resistor and a difference between the reference voltage and the second voltage.

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Winston Salem, NC, United States of America

Walter H Prada