Variable Capacitive Delay Stage for Low-Jitter VCO Frequency Control
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Solution Overview
Problem
Voltage controlled oscillators (VCOs) are adversely affected by noise and non-ideal factors, leading to phase jitter and inconsistent signal edge spacing, necessitating improved adjustable delay stage designs.
Innovation Solution
The implementation of controllably variable capacitor load sections in VCOs, comprising separate variable capacitor circuits that adjust capacitance based on control signals and temperature compensation to stabilize frequency response, comprising PMOS and NMOS transistors and capacitors, and a temperature compensation circuit to mitigate temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If adjustable delay stage designs are used in VCOs to control output frequency, then frequency controllability is improved, but phase jitter and signal edge consistency deteriorate due to noise and non-ideal factors
Solution Approach 1:
The patent applies dynamics by making the capacitive load adjustable and controllable. The delay stage includes a controllable capacitive load that can be dynamically modified through control signals, allowing the VCO to adjust its output frequency while maintaining stable operation. The variable capacitor circuit changes its capacitance value based on control inputs, enabling adaptive frequency control without sacrificing signal integrity.
Solution Approach 2:
The patent implements parameter changes by modifying the capacitive load parameter in the delay stage. By changing the capacitance value of the controllable capacitive load, the delay time and consequently the output frequency are adjusted. This parameter modification approach allows frequency control while the circuit maintains consistent signal edge spacing through proper design of the variable capacitor implementation.
2Adaptability or versatility
If controllable capacitive load is added to delay stages for frequency control, then frequency adjustability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the controllable capacitive load to serve multiple functions. The variable capacitor circuit not only provides frequency control but also maintains signal integrity and can be integrated into existing VCO architectures. The control mechanism is designed to work with standard control signals, making it compatible with various VCO designs and reducing overall system complexity despite the added functionality.
Solution Approach 2:
The patent uses an intermediary approach by introducing a control signal as a mediator between the frequency control requirement and the capacitive load. The control signal indirectly adjusts the capacitance value through the variable capacitor circuit, allowing frequency control without direct mechanical or complex electrical adjustments. This intermediary control mechanism simplifies the overall system by using standard control interfaces.
3Measurement precision
If variable capacitor circuits are used to control delay stage load, then frequency control precision is improved, but sensitivity to temperature variations increases
Solution Approach 1:
The patent implements feedback by monitoring the actual capacitance value or delay time and using this information to adjust the control signal to the variable capacitor. This feedback mechanism compensates for temperature-induced variations in capacitance, maintaining precise frequency control despite environmental changes. The control system continuously adjusts the capacitive load to maintain the desired delay and frequency output.
Solution Approach 2:
The patent addresses temperature sensitivity through parameter changes by dynamically adjusting the capacitance value to compensate for temperature effects. As temperature varies, the control system modifies the effective capacitance parameter to maintain consistent frequency control precision. This adaptive parameter adjustment counteracts the temperature-dependent behavior of the capacitor components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces phase jitter and temperature-induced frequency variations, providing stable and controllable frequency output with improved noise resistance and temperature compensation.
Implementation Method 1
Delay stages typically comprise an odd number of inverters coupled together in a ring oscillator configuration, with one or more of the inverter outputs adjustably loaded to control the frequency of the ring oscillator
Implementation Method 2
The implementation of controllably variable capacitor load sections in VCOs, comprising separate variable capacitor circuits that adjust capacitance based on control signals and temperature compensation to stabilize frequency response
Data Source
AI summary
Disclosed herein are embodiments of controllably variable capacitor loads that may be used with delay stages or other elements, for example, in a voltage controlled oscillator.