Patent ID: 7589575

Claim:
A loop filter in a phase lock loop circuit, the loop filter comprising: a reference precision resistor; a first field effect transistor and a second field effect transistor, wherein a gate of the first field effect transistor is tied to a gate of the second field effect transistor; and a filter capacitor connected to the first field effect transistor for producing a capacitor voltage, wherein the capacitor voltage is applied to the source of the first field effect transistor, the source of the second field effect transistor, and to a bottom of the reference precision resistor acting as a virtual ground, wherein the capacitor voltage generated by the filter capacitor sets a bias point of the second field effect transistor such that the second field effect transistor comprises characteristics of an integrated precision resistor; and wherein a predetermined voltage generated by the second field effect transistor is applied to the gate of the first field effect transistor to set a bias point of the first field effect transistor such that the first field effect transistor comprises characteristics of an integrated precision resistor.