Ring Oscillator Phase Realignment for Low-Noise PLL Stability
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Solution Overview
Problem
Current ring oscillators in phase-locked loop (PLL) circuits face challenges in reducing phase noise and frequency variations due to process, voltage, and temperature (PVT) variations, which affects their performance in applications such as network controllers and graphics processors.
Innovation Solution
The implementation of a ring oscillator with a controlling circuit and a delay chain that includes pseudo pass-gate inverters and transistors, where a realignment signal is used to enable or disable the pseudo pass-gate inverter, allowing for phase alignment without additional electronic components, thereby reducing phase noise and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional electronic components are added to align the phase of the ring oscillator, then the phase alignment precision is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent implements self-service by using the existing ring oscillator's own waveform to control the switching of transistors that adjust its phase. The oscillating signal directly drives the gates of adjustment transistors, creating a feedback mechanism where the system adjusts itself without external control components, thereby achieving phase alignment without adding complexity.
Solution Approach 2:
The patent makes existing components multi-functional by having the delay chain serve both as a frequency divider and as a phase adjustment mechanism. The same transistors and delay elements that generate the oscillation waveform also control the phase alignment, eliminating the need for separate control components and reducing overall device complexity.
2Measurement precision
If additional electronic components are added to align the phase of the ring oscillator, then the phase alignment precision is improved, but the manufacturing cost increases
Solution Approach 1:
The system uses its own oscillating waveform to control the phase adjustment process, eliminating the need for external control circuits and additional components. This self-service approach reduces component count and simplifies manufacturing while maintaining precise phase alignment capability.
Solution Approach 2:
The patent merges the phase generation and phase adjustment functions into a single integrated structure. The delay chain and adjustment transistors serve dual purposes: generating the oscillation waveform and controlling the phase alignment, thereby reducing the total number of components and lowering manufacturing costs.
3Adaptability or versatility
If the ring oscillator operates across wide frequency range for PVT variations, then the adaptability is improved, but the phase noise increases
Solution Approach 1:
The patent implements dynamic phase adjustment by using the oscillating waveform to dynamically control the switching of adjustment transistors. This dynamic control mechanism allows the system to adapt to PVT variations and maintain stable operation across a wide frequency range while minimizing phase noise through real-time waveform alignment.
Solution Approach 2:
The system employs feedback by using the ring oscillator's own output waveform to control the phase adjustment process. The oscillating signal feeds back to the gates of adjustment transistors, creating a closed-loop system that automatically compensates for phase deviations and reduces phase noise across varying frequency conditions.
4Adaptability or versatility
If the ring oscillator operates across wide frequency range for PVT variations, then the adaptability is improved, but the power consumption increases
Solution Approach 1:
The patent uses periodic action by leveraging the natural oscillating waveform to periodically control the switching of adjustment transistors. This periodic control mechanism enables the system to adapt to PVT variations across a wide frequency range while consuming minimal power, as the switching is driven by the existing oscillation rather than continuous external control signals.
Solution Approach 2:
The adjustment transistors serve multiple functions: they participate in generating the oscillation waveform and simultaneously control the phase alignment. This multi-functionality reduces the need for separate control circuits, thereby lowering overall power consumption while maintaining adaptability across wide frequency ranges.
Data Source
AI summary
A controlling circuit for ring oscillator is provided. A first transistor and a second transistor of a first conductive type are coupled in series and between a node and a first power source. A third transistor and a fourth transistor of a second conductive type are coupled in parallel and between the node and a second power source. The node is coupled to an input of a delay chain of the ring oscillator. The second and third transistors are coupled in series. Gates of the second and third transistors are configured to receive an output signal of the delay chain. When the first transistor is turned off and the fourth transistor is turned on, the node is pulled to a first logic level from a second logic level in order to align a phase of a waveform of the ring oscillator.