Schmitt Trigger Ring Oscillator for Stable Low-Power Frequency
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Solution Overview
Problem
Ring oscillators in existing technologies are sensitive to variations in elements, leading to unstable oscillatory frequencies, while Phase Lock Loop (PLL) circuits achieve stability but at the cost of high power consumption.
Innovation Solution
An oscillator design featuring inverters connected in a loop shape with an odd number greater than or equal to three, including a schmitt trigger inverter with a current source and resistor, where the hysteresis width depends on the current flowing through the resistor, allowing for adjustable oscillatory frequency with low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a ring oscillator is used, then the power consumption is low, but the oscillatory frequency becomes unstable due to element variation
Solution Approach 1:
The patent introduces a feedback mechanism by connecting the output of the last inverter back to the input of the first inverter, forming a closed loop. This feedback structure allows the oscillator to self-regulate and maintain stable oscillation frequency despite element variations, while keeping power consumption low compared to PLL circuits.
Solution Approach 2:
The patent utilizes the hysteresis characteristic of the Schmitt trigger inverter, where the threshold voltage changes based on the input signal state. This parameter change mechanism creates a stable oscillation condition that is less sensitive to element variations, resolving the contradiction between low power consumption and frequency stability.
2Reliability
If a PLL circuit is used, then the oscillatory frequency becomes stable, but the power consumption increases
Solution Approach 1:
The patent extracts only the essential feedback mechanism needed for frequency stability from the complex PLL circuit structure. By implementing a simplified ring oscillator with Schmitt trigger inverters and a feedback loop, it achieves frequency stability without requiring the additional components and power consumption of a full PLL circuit.
3Reliability
If element variations occur, then the oscillatory frequency fluctuates, but using more complex circuits to stabilize frequency increases power consumption
Solution Approach 1:
The Schmitt trigger inverter provides self-service by automatically adjusting its threshold voltage based on its own output state. This self-regulating characteristic compensates for element variations without requiring external control circuits, maintaining frequency stability while keeping the circuit simple and power consumption low.
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 improves tolerance to element variations and reduces power consumption, achieving stable oscillations while being less dependent on element thresholds, and can be integrated into imaging apparatuses like digital cameras for efficient operation.
Implementation Method 1
The one inverter is a schmitt trigger inverter. The schmitt trigger inverter includes a current source, and a resistor in which current supplied by the current source flows. A hysteresis width of the schmitt trigger inverter depends on the current which flows in the resistor.
Data Source
AI summary
An oscillator includes: inverters that are connected in a loop shape and of which the number is an odd number greater than or equal to three; and a delay section that delays change in a voltage which is input to one inverter of the odd number of inverters. The one inverter is a schmitt trigger inverter. The schmitt trigger inverter includes a current source, and a resistor in which current supplied by the current source flows. A hysteresis width of the schmitt trigger inverter depends on the current which flows in the resistor.