Temperature-Compensated Ring Oscillator Using Bias and Voltage Control
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Solution Overview
Problem
Conventional ring oscillator designs for generating ultra-low current reference clock signals struggle to maintain stable frequency characteristics with respect to temperature changes, requiring multiple resistance elements that are difficult to implement effectively.
Innovation Solution
A temperature-compensated oscillator design that includes an oscillation unit with an odd number of inverters connected in series, a bias circuit to increase operating current with temperature, and a voltage generation unit to adjust operating voltage, ensuring the frequency remains stable across temperature changes by offsetting variations in operating current and voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional temperature-compensated current circuit is used in ring oscillator, then frequency stability with respect to temperature is improved, but circuit complexity and current consumption increase
Solution Approach 1:
The patent merges the temperature compensation function into the existing ring oscillator circuit by using the same inverter chain for both oscillation and temperature compensation. The oscillation unit generates both the clock signal and the temperature compensation signal, eliminating the need for separate compensation circuits and reducing overall circuit complexity.
Solution Approach 2:
The inverter chain in the oscillation unit serves multiple functions: generating the clock signal, providing temperature compensation, and generating the compensation signal for the current source. This multi-functionality reduces the number of dedicated components needed for temperature compensation while maintaining frequency stability.
2Stability of the object's composition
If multiple resistance elements are used for temperature compensation, then frequency stability is improved, but manufacturing difficulty and area increase
Solution Approach 1:
The patent extracts the temperature compensation function from traditional resistor-based circuits and implements it using transistor-based current sources and inverter chains. This eliminates the need for multiple high-value resistance elements (several MΩ to tens of MΩ), simplifying the manufacturing process and reducing the circuit area.
Solution Approach 2:
The patent changes the implementation approach from using resistance elements to using transistor parameters (threshold voltages, channel widths, lengths) to achieve temperature compensation. By adjusting transistor dimensions and characteristics, the desired temperature compensation effect is obtained without requiring large resistance values that are difficult to manufacture.
3Use of energy by moving object
If ultra-low current operation is implemented, then power consumption is reduced, but frequency stability with respect to temperature deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the oscillation unit generates a temperature compensation signal based on the actual temperature conditions, which is then fed back to the current source to adjust the bias current. This closed-loop feedback ensures frequency stability across temperature variations while maintaining ultra-low current operation, as the compensation is adaptive rather than requiring excessive static current.
Solution Approach 2:
The patent uses dynamic temperature compensation where the compensation amount adjusts automatically with temperature changes rather than using fixed high current levels. The bias circuit dynamically modifies the current based on temperature, allowing ultra-low current operation at nominal temperatures while providing adequate compensation when temperature varies, thus maintaining stability without continuously consuming high current.
Data Source
AI summary
A temperature-compensated oscillator and a device including the same include an oscillation unit configured to generate an oscillation signal using an operating current and an operating voltage, a bias circuit configured to control the operating current so that a frequency of the oscillation signal increases as a temperature increases, and a voltage generation unit configured to generate the operating voltage that varies with the temperature.