Differential Ring Oscillator Switching for Lower Phase Noise
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Solution Overview
Problem
Conventional single-ended and differential ring oscillators are sensitive to noise, leading to poor anti-interference performance and high phase noise, which affects their overall performance.
Innovation Solution
A ring oscillator design incorporating at least three differential inverting amplifiers with specific polarity coupling and switchable configurations to enhance noise cancellation and phase noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-ended ring oscillator is used, then device complexity is reduced, but anti-interference performance deteriorates due to sensitivity to power supply and ground noise
Solution Approach 1:
The patent divides the oscillator into multiple differential stages (at least three differential inverting amplifiers) coupled in a ring configuration. Each stage processes differential signals separately, allowing noise rejection while maintaining oscillation functionality. This segmentation enables the system to achieve both simplicity and reliability.
Solution Approach 2:
The patent employs differential signaling where the first input end and second input end have opposite polarities, creating an asymmetric structure that naturally rejects common-mode noise. The differential inverting amplifiers process signals with opposite phases, enabling noise cancellation while maintaining the oscillation signal integrity.
2Reliability
If conventional differential ring oscillator is used, then anti-interference performance is improved, but phase noise increases due to long noise conversion time
Solution Approach 1:
The patent implements periodic switching of the first and second switches to control the coupling between the first differential inverting amplifier and subsequent stages. This periodic action regulates the noise conversion process, reducing the time available for noise to convert into phase noise while maintaining the beneficial anti-interference properties of differential signaling.
Solution Approach 2:
The patent introduces dynamic control through switches that can change the coupling configuration of the differential inverting amplifiers. By dynamically adjusting which stages are coupled and how signals flow through the ring oscillator, the system optimizes the balance between noise rejection and phase noise generation in real-time.
3Object-generated harmful factors
If multiple differential inverting amplifiers are coupled in ring with specific polarity configuration, then phase noise is reduced, but device complexity increases
Solution Approach 1:
The patent designs the differential inverting amplifiers to serve multiple functions: they provide signal amplification, differential noise rejection, and phase inversion simultaneously. The first differential inverting amplifier with its specific polarity configuration (first polarity for first input/output, second polarity for second input/output) performs multiple roles that would otherwise require separate components, reducing overall system complexity.
Solution Approach 2:
The patent merges the functionality of multiple differential stages into a unified ring oscillator structure where the first differential inverting amplifier is directly coupled to itself in a feedback configuration. This merging of functions and components achieves phase noise reduction through the differential structure while avoiding the complexity of separate control circuits for each stage.
Data Source
AI summary
This application provides a ring oscillator and a communication apparatus. In one example, the ring oscillator includes at least three differential inverting amplifiers that are coupled in a ring. A first output end and a second output end of each differential inverting amplifier are respectively coupled to a first input end and a second input end of a next adjacent differential inverting amplifier. The at least three differential inverting amplifiers include a first differential inverting amplifier, a first input end of the first differential inverting amplifier is coupled to a first output end of the first differential inverting amplifier, and a second input end of the first differential inverting amplifier is coupled to a second output end of the first differential inverting amplifier.