VARACTORLESS TUNABLE OSCILLATOR

摘要

A tunable oscillator circuit is disclosed. The tunable oscillator circuit includes an inductor/capacitor (LC) tank circuit comprising a primary inductor coupled in parallel with a first capacitor bank. The LC tank resonates to produce an oscillating voltage at a frequency. The tunable oscillator circuit also includes a 90 degree phase shift buffer coupled to the LC tank and a transconductor. The transconductor is coupled to the 90 degree phase shift buffer and a secondary inductor. The tunable oscillator circuit also includes a secondary inductor that is inductively coupled to the primary inductor and receives a gain-scaled oscillating current from the transconductor. By changing the transconductance, the gain-scaled oscillating current in the secondary inductor will change, thus the effective primary inductance and the oscillation frequency can be tuned.