Patent ID: 6812798
Filing Date: 2004-11-02
Classification: H03B

Abstract:
A quadrature oscillator comprising:two symmetrical oscillators (11) (12), each being connected by two transistors (M1, M2) (M3, M4) self-coupled in a positive feedback structure to produce negative resistance; two LC circuits (13) (14), being connected to the respective oscillator (11) (12) to produce positive resistance offsetting the negative resistance through the above oscillator (11) (12); two coupling circuits (15) (16) being series connected to the respective oscillators (11) (12) and LC circuits (13) (14) to produce quadrature phase outputs; wherein the two coupling circuits (15) (16) are each formed by two transistors (M5, M6), (M7, M8); whereby gate terminals of the transistor pairs of the two coupling circuit (M5, M6), (M7, M8) are respectively connected to the drain terminals of the transistor pairs (M1, M2) (M3, M4) in the oscillators (11) (12), the transistor pairs of the two coupling circuit (M5, M6), (M7, M8) are respectively connected to constant current sources (17) (18); and drain terminals of the transistor pairs (M5, M6) (M7, M8) in the coupling circuits (15) (16) are respectively connected in series to the source terminals of the transistor pairs (M1, M2) (M3, M4) in the oscillators (11) (12).