Current-Controlled VCO Structure for Linear Low-Power PLLs
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Solution Overview
Problem
Existing voltage controlled oscillators in phase-locked loops have high power consumption and low voltage to frequency linearity, which hinders the formation of high-performance phase-locked loops.
Innovation Solution
A voltage controlled oscillator structure incorporating a voltage-to-current conversion module and a current controlled oscillation module, where the voltage-to-current conversion module converts control voltage into a linear control current and the current controlled oscillation module outputs low-amplitude oscillation signals, reducing power consumption and improving linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a typical fully differentiated ring oscillator structure is used, then the oscillator can generate frequency signals, but the power consumption is high
Solution Approach 1:
The patent changes the control parameter from voltage directly controlling current in traditional VCOs to a two-stage process where control voltage first converts to control current through a voltage-to-current conversion module, then the control current regulates the oscillation. This parameter transformation improves linearity and reduces power consumption while maintaining performance
Solution Approach 2:
The patent introduces a control current IM as an intermediary between the control voltage VC and the oscillation generation. The voltage-to-current conversion module converts VC to IM, which then controls the current controlled oscillation module. This intermediary improves the linearity of voltage-to-frequency conversion and optimizes power consumption
2Measurement precision
If a typical voltage controlled oscillator structure is used, then frequency can be controlled by voltage, but the voltage to frequency linearity is low
Solution Approach 1:
The patent segments the VCO into two independent modules: a voltage-to-current conversion module and a current controlled oscillation module. This segmentation allows each module to be optimized independently, with the conversion module ensuring linear voltage-to-current transformation and the oscillation module efficiently generating frequency, thereby improving overall voltage-to-frequency linearity
Solution Approach 2:
The control current IM serves as an intermediary that linearizes the voltage-to-frequency relationship. The voltage-to-current conversion module ensures that VC is converted to IM with high linearity, and this linear control current then controls the oscillation frequency, resulting in improved voltage-to-frequency linearity throughout the system
Data Source
AI summary
The present invention includes a voltage controlled oscillator circuit and a phase-locked loop device. The voltage controlled oscillator circuit comprises: a voltage-to-current conversion module, used for converting a control voltage of a voltage controlled oscillator into a control current as a linear function of the control voltage; and a current controlled oscillation module, used for outputting a low-amplitude oscillation signal based on the control current, so as to reduce power consumption. Further provided in the present invention is a phase-locked loop device comprising the voltage controlled oscillator circuit. According to the voltage controlled oscillator circuit, design parameters of low power consumption and high linearity may be achieved, thereby making a gain Kvco of the voltage controlled oscillator relatively stable, and it may be ensured that the voltage controlled oscillator and the phase-locked loop comprising the same have relatively excellent device performance.