CAPACITIVE-DEGENERATION DOUBLE CROSS-COUPLED VOLTAGE-CONTROLLED OSCILLATOR

摘要

A capacitive-degeneration double cross coupled voltage controlled oscillator is provided to reduce a phase noise by reducing the input capacitance. A main cross coupled oscillator(321) includes an oscillator transistor pair cross coupled with a first output node and a second output node of a resonator and performs an oscillation operation. A positive feedback transistor pair is cross coupled in the firs and second output node of the resonator and the transistor pair of the main cross coupled oscillator. The main cross coupled oscillator includes a first transistor, a second transistor, and a second current source. The bases of the first and second transistors are connected to the first and second output node respectively. The collector is cross coupled with the base. The second current source is connected to the emitters of the first and second transistors. An auxiliary cross coupled oscillator(322) includes a positive feedback transistor pair and a degeneration capacitance and increase the negative resistance of the main cross coupled oscillator.