Voltage control oscillator with low phase noise

Abstract

This invention provides a voltage controlled oscillator with low phase noise containing a LC resonant loop, a negative resistance generation circuit and a noise suppression loop including a T(or delta) base bias resistant circuit, the said noise suppression loop is for reducing the noise of the said voltage-controlled oscillator and improving its phase noise performance.

Description

technical field [0001] The invention provides an oscillator, in particular to an oscillator circuit structure capable of reducing the phase noise in the oscillator and improving the signal-to-noise ratio of the oscillator. Background technique [0002] High frequency differential voltage controlled oscillator (VCO) has been widely used in various communication systems, and this type of voltage controlled oscillator can be applied to integrated circuits, and even communication systems can achieve Light, thin, and short are required, and the quality of a voltage-controlled oscillator depends on whether it has low phase noise (phase noise) and high signal-to-noise ratio (SNR). [0003] Please refer to figure 1 , figure 1 is a circuit diagram of a known oscillator 10 disclosed in US Pat. No. 6,064,277. The oscillator 10 uses a drive circuit 12 to drive an LC tank 11 . The LC resonant tank 11 includes an inductor L and a capacitor C for generating sinusoidal waves. The drivi...

AI Technical Summary

Problems solved by technology

However, since the noise at the output of the bias circuit 14 can be amplified by the even-order harmonics through the transistors Q1 and Q2, the relative noise level (Noise Level) is increased

This feature relatively degrades the phase noise of the oscillator

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