Method and apparatus to electronically enhance the tank quality factor of tank circuits and oscillators having tank circuits

摘要

Methods and apparatus to control and enhance the quality factor of a tank circuit and oscillators having a tank circuit by feeding back a voltage to the tank circuit in opposition to the losses in the tank circuit. In an exemplary embodiment, a degenerate common emitter stage, responsive to the voltage across a differential circuit, has magnetically coupled inductors coupling voltages back to a differential tank in opposition to the IR voltage losses in the differential tank circuit. The amount of feedback may be controlled by the bias on the common emitter stage. Various embodiments are disclosed.