Ring Oscillator Clock Circuit With Opposed Voltage Ramps
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Solution Overview
Problem
There is a need for a clock generation circuit that consumes low power and is less dependent on temperature variations, particularly for electronic devices that operate in varying ambient temperatures and require extended battery life.
Innovation Solution
A clock generator circuit comprising a first capacitor, a current source, and switches, with a comparator controlling the switches to manage the capacitor's voltage nodes, allowing for efficient clock signal generation with low power consumption and reduced temperature sensitivity, utilizing a ring oscillator topology and XOR gate to produce a clock signal at twice the frequency with a 90-degree phase offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional clock generation circuits are used, then clock signal can be generated, but power consumption is high and temperature dependence is significant
Solution Approach 1:
The patent implements periodic action through voltage ramps that cyclically charge and discharge capacitors in the ring oscillator stages. Each stage alternates between charging phases (voltage increasing) and discharging phases (voltage decreasing), creating periodic oscillations that generate the clock signal. This periodic charging/discharging through controlled current sources reduces average power consumption compared to continuous operation while maintaining reliable oscillation across temperature variations.
Solution Approach 2:
The patent applies parameter changes by using temperature-compensated current sources that adjust their output current based on temperature conditions. The current sources modify their parameters (current magnitude) in response to temperature changes, thereby compensating for temperature-dependent variations in the ring oscillator stages. This dynamic parameter adjustment maintains stable oscillation frequency and reduces temperature dependence while managing power consumption efficiently.
2Duration of action of moving object
If conventional clock generation circuits are used, then clock signal can be generated, but battery life is reduced
Solution Approach 1:
The periodic charging and discharging of capacitors through controlled current sources creates oscillations with duty cycles that can be optimized for low power operation. By implementing periodic action rather than continuous operation, the circuit reduces average current draw from the power supply, directly extending battery life while maintaining the necessary clock signal generation function.
Solution Approach 2:
The ring oscillator circuit is self-sustaining, using its own output signal to control the switching of current sources that charge and discharge the capacitors. The oscillation automatically regulates itself through the feedback mechanism inherent in the ring topology, eliminating the need for external control circuits that would consume additional power. This self-service operation maximizes battery life by minimizing overall power consumption.
3Use of energy by moving object
If ring oscillator topology is used with opposed voltage ramps, then low power consumption is achieved, but circuit complexity increases
Solution Approach 1:
The patent merges multiple functions into unified circuit blocks. Each ring oscillator stage combines the voltage ramp generation, comparison logic, and clock signal output into a single integrated stage. The current sources serve dual purposes of charging capacitors and providing temperature compensation. This merging reduces the number of discrete components and simplifies the overall circuit architecture while maintaining low power consumption through the opposed voltage ramp mechanism.
Solution Approach 2:
The current sources in the circuit perform multiple functions: they charge the capacitors during the voltage ramp-up phase, provide temperature compensation across operating conditions, and can be controlled to adjust oscillation frequency. By designing universal current sources that serve multiple purposes rather than dedicated components for each function, the circuit achieves low power consumption without proportionally increasing complexity.
Data Source
AI summary
A clock generator comprises a first capacitor, a current source, and a voltage node. A first switch is coupled between the first capacitor and the current source. A second switch is coupled between the first capacitor and voltage node.