Patent ID: 7075377

Claim:
A quadrature oscillator circuit for generating in phase and quadrature signals comprising: a first differential oscillator having a differential input and a differential output; a second differential oscillator having a differential input and a differential output, the first and second differential oscillators being alike; the differential output of said first differential oscillator being connected to the differential input of said second differential oscillator; the differential output of said second differential oscillator being connected in a cross-coupled manner to said differential input of said first differential oscillator; whereby the differential output of said first differential oscillator will be ninety degrees from the differential output of said second differential oscillator, and each of said first and second differential oscillators comprises: a differential Colpitts oscillator connected in a common base mode and adapted to be coupled to another differential Colpitts oscillator, the differential Colpitts oscillator and coupled to a capacitor bank enabling discrete selection of a resonant frequency by connecting or disconnecting a plurality of capacitors from the capacitor bank to the differential Colpitts oscillator; a first differential transconducting amplifier coupled to said differential Colpitts oscillator for accelerating oscillation of said differential Colpitts oscillator; a second differential transconducting amplifier coupled to said differential Colpitts oscillator for connecting the differential input of said differential oscillator to the differential output of said other differential oscillator; and, a current source coupled to said first differential transconducting amplifier to supply a bias current for said differential Colpitts oscillator.