A Low Phase Noise LC Voltage Controlled Oscillator

Abstract

The invention relates to the technical field of LC-VCOs, in particular to a low phase noise LC-VCO. The current switching speed of a cross-coupling MOS pipe is improved, the current waveform duty ratio of the cross-coupling MOS pipe is reduced, and phase noise of the low phase noise LC-VCO due to the cross-coupling MOS pipe is further lowered. In addition, the number of traps of an NMOS pipe of a tail current source is reduced, and the phase noise of the low phase noise LC-VCO is further reduced. Energy provided by cross-coupling negative resistance is improved, the oscillation waveform amplitude of an oscillation circuit is improved, and the phase noise of the low phase noise LC-VCO is further reduced.

Description

technical field [0001] The invention relates to the technical field of an inductor-capacitor voltage-controlled oscillator, in particular to a low-phase-noise inductor-capacitor voltage-controlled oscillator. Background technique [0002] The LCC voltage-controlled oscillator is a key module in the clock generation and clock synthesis circuit, and the LCC voltage-controlled oscillator is usually used to generate high-frequency oscillation signals. However, as the oscillation frequency increases, the very small jitter of the oscillation waveform has a great impact on the work of other circuits, so as the frequency increases, the phase noise requirements for low phase noise LC VCOs become more and more severe. getting stricter. [0003] In the low-phase-noise LC voltage-controlled oscillator, the inductance and capacitance are connected in parallel to form a resonant circuit. After enough energy is supplied to the resonant circuit by the outside world, the resonant circuit os...

AI Technical Summary

Problems solved by technology

In addition, the tail current source MOS tube of the low-phase noise inductor-capacitor voltage-controlled oscillator will generate traps when it is working. These traps will increase the noise of the current flowing on the tail current source, thereby affecting the spectral purity of the oscillation waveform of the resonant circuit. Increased output waveform phase noise

[0005] When the resonant circuit oscillates, the oscillating waveform is easily disturbed by the surrounding noise. If the amplitude of the oscillating waveform is small, the external interference will be more serious, which will increase the phase noise of the output waveform

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