A quadrature oscillator capable of lowering phase noise and power dissipation is disclosed. The oscillator circuit includes two symmetrical oscillators (11) (12) formed by cross-coupled transistor pairs with positive feedback structure to produce negative resistance, two LC circuits (13) (14) coupled to the above oscillators (11) (12) to produce positive resistance offsetting the negative resistance through the oscillators (11) (12), and two coupling circuits (15) (16) coupled to the oscillators (11) (12) to produce quadrature phase outputs, wherein, the transistor pairs in each coupling circuit (15) are respectively connected to the corresponding transistor pairs in the two oscillators (11) (12), to prevent the operating point of the oscillator transistors from shifting toward the linear region.
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