Patent ID: 9166607
Filing Date: 2015-10-20
Classification: H03L

Abstract:
1. A circuit comprising: a loop filter comprising a capacitor; a charge pump comprising a charge pump output node, a first operational amplifier, and a Charge Pump Output Voltage Replica Node (CPOVRN), wherein the charge pump output node is coupled to the loop filter, and wherein the CPOVRN is directly coupled to a high impedance noninverting input lead of the first operational amplifier; and a capacitor leakage compensation circuit having a second operational amplifier and an output node, wherein the second operational amplifier comprises a noninverting input lead, an inverting input lead, and an output lead, wherein the inverting input lead is directly coupled to the CPOVRN, wherein the noninverting input lead is directly coupled to a replica capacitor and the output node of the capacitor leakage compensation circuit is coupled to the capacitor of the loop filter, wherein the capacitor leakage compensation circuit senses a sense voltage present on the CPOVRN and imposes this sense voltage across the replica capacitor, wherein the capacitor leakage compensation circuit supplies a compensation current onto a plate of the capacitor, and wherein the sense voltage across the replica capacitor is substantially identical to a voltage across the capacitor.