Patent ID: 8198945

Claim:
An oscillator circuit for generating an in-phase signal and a quadrature signal, said oscillator circuit comprising: a) first oscillator means comprising a first differential oscillator circuit and a first differential coupling circuit, for generating said quadrature signal; b) second oscillator means comprising a second differential oscillator circuit and a second differential coupling circuit, for generating said in-phase signal; and c) frequency control means for varying the oscillation frequency of said in-phase signal and said quadrature signal by controlling at least one of a common-mode current and a tail current of said first and second oscillator means, wherein said first and second differential oscillator circuits each comprise a differential Colpitts type oscillator, wherein said first and second differential Colpitts type oscillators each comprise a first differential transistor stage as an under-stage for combining tail currents of a second differential transistor stage, wherein respective control terminals of the transistors of said second differential transistor stage are connected at a bias point which forms a common-mode point of coils of a tank circuit of said first and second differential oscillator circuits.