METHOD AND APPARATUS FOR CAPACITANCE MULTIPLICATION WITHIN A PHASE LOCKED LOOP

摘要

A method and apparatus for capacitance multiplication using two charge pumps. A first charge pump ( 206 ) provides a current signal (I₂₁₆) that is first conducted by a resistor ( 310 ) of an RC network and then split into three current paths prior to being conducted by a capacitor of the RC network. A first current path provides current to the capacitor ( 306 ) of the RC network from node ( 320 ). A second current path multiplies the current conducted by capacitor ( 306 ) by a first current multiplication factor. A third current path provides current to a second charge pump, which multiplies the current from the first charge pump by a second current multiplication factor that has a fractional value with an inverse magnitude sign relative to the first current multiplication factor. The combination of the second and third current paths effectively multiplies the capacitance magnitude of capacitor ( 306 ).