Patent ID: 8665033

Claim:
A tunable oscillator circuit, comprising: an inductor/capacitor (LC) tank circuit comprising a primary inductor coupled in parallel with a first varactorless capacitor bank, wherein the LC tank circuit resonates to produce an oscillating voltage at a frequency; a 90 degree phase shift buffer coupled to the LC tank circuit and to a transconductor, wherein the 90 degree phase shift buffer includes a programmable shunt capacitor bank with a first node coupled to the transconductor, wherein the transconductor includes a first n-type metal oxide semiconductor (NMOS) transistor that receives a tuning current at a first source and a tuning voltage at a first gate, wherein the tuning current corresponds to an input current from a digital phase locked loop that is mirrored via a second NMOS transistor, and wherein the tuning voltage corresponds to an input voltage from an analog phase locked loop; and a secondary inductor coupled to the transconductor, wherein the secondary inductor is inductively coupled to the primary inductor and receives a gain-scaled oscillating current from the transconductor.