Ring Oscillator Start-Up Using AC-Coupled Differential Injection
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Solution Overview
Problem
Conventional methods for controlling the start-up of ring oscillators face issues with power consumption, robustness, reliability, and complexity, often resulting in start-up failure and inefficient design.
Innovation Solution
A method involving the detection of stable operating points, measurement of equivalent impedance, configuration of a start-up circuit using AC coupling capacitors and switches, and application of a differential start-up voltage to force the ring oscillator into oscillation, reducing power consumption and start-up failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional startup control circuits are implemented to support high supply voltages, then the ring oscillator can be initialized, but power consumption increases and circuit complexity increases
Solution Approach 1:
The patent extracts and removes the conventional startup control circuit from the ring oscillator design. By eliminating the startup control circuit entirely and using natural oscillator startup mechanisms, the patent reduces power consumption while maintaining startup reliability through alternative design approaches.
Solution Approach 2:
The ring oscillator is designed to self-start without external startup control circuits. The oscillator naturally initializes through its inherent positive feedback mechanism and latch gain, eliminating the need for separate startup control components and their associated power consumption.
2Reliability
If conventional startup control circuits are implemented, then the ring oscillator can be initialized, but circuit complexity and hardware components increase
Solution Approach 1:
The patent removes conventional startup control circuits, Schmitt triggers, and associated hardware components from the design. The ring oscillator relies on its fundamental latch-based positive feedback mechanism to achieve startup, significantly reducing circuit complexity and hardware requirements.
Solution Approach 2:
The latch circuit serves multiple functions: it provides the core oscillation mechanism, ensures startup reliability through positive feedback, and eliminates the need for separate startup control circuits. This multi-functionality reduces overall circuit complexity while maintaining initialization capability.
3Reliability
If direct current (DC) coupling is used to initialize oscillator nodes, then startup can be achieved, but leakage current increases and reliability decreases
Solution Approach 1:
The patent replaces DC coupling mechanisms with an AC-based oscillation startup approach. The ring oscillator uses its inherent latch gain and positive feedback to naturally initialize oscillations without requiring DC coupling capacitors or associated leakage current paths, thereby eliminating this harmful effect.
4Reliability
If conventional startup methods are used, then initialization can be achieved, but area and power consumption increase due to larger latch ratio requirements
Solution Approach 1:
The ring oscillator design achieves startup reliability through its inherent latch mechanism and positive feedback without requiring enlarged latch ratios. The natural oscillation startup mechanism eliminates the need for additional area-consuming components while maintaining reliable initialization.
Solution Approach 2:
The patent optimizes the latch ratio parameter to its minimum necessary value for reliable operation. By using the inherent latch gain for both oscillation and startup functions, the design achieves startup reliability with a smaller latch ratio, thereby reducing circuit area compared to conventional designs that require larger ratios for startup assurance.
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 approach reduces power consumption, minimizes start-up failure, and allows for a smaller latch ratio, leading to area and power reduction in the ring oscillator design.
Implementation Method 1
a plurality of AC coupling capacitors receiving the first output and the second output
Data Source
AI summary
A ring oscillator includes at least one oscillator stage having a first output and a second output and a start-up circuit. The start-up circuit includes a plurality of AC coupling capacitors receiving the first output and the second output, and a plurality of switches connected to the AC coupling capacitors. The start-up circuit is configured to provide a differential start-up voltage to at least one node of the oscillator using the plurality of switches and the AC coupling capacitors.