Patent ID: 7852165

Claim:
A voltage-controlled oscillator comprising: a main cross-coupled oscillating unit including first and second transistors cross-coupled to first and second output nodes of a resonating unit to perform an oscillation operation; and an auxiliary cross-coupled oscillating unit including third and fourth transistors cross-coupled to the first and second output nodes and the first and second transistors and a degeneration capacitor connected between emitters of the first and second transistors so as to form a positive-feedback loop capable of increasing a negative resistance and decreasing an input capacitance by the positive-feedback loop, wherein the positive-feedback loop is contributed to by the first transistor, the fourth transistor, the degeneration capacitor, the third transistor and the second transistor, wherein the auxiliary cross-coupled oscillating unit comprises: the third transistor having a collector connected to the base of the first transistor and a base connected to the emitter of the second transistor; the fourth transistor having a collector connected to the base of the second transistor and a base connected to the emitter of the first transistor; the degeneration capacitor connected between emitters of the third and fourth transistors; and a first current source connected to emitters of the third and fourth transistors.