On-Chip Temperature Sensing via Dual-Oscillator Frequency Ratio
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Solution Overview
Problem
Conventional temperature sensing techniques in integrated circuits require an external clock signal, which is not always available due to cost constraints and instability, necessitating an on-chip temperature sensing device without an external reference clock signal.
Innovation Solution
An on-chip temperature sensing device comprising a reference generating circuit, two oscillators, and an arithmetic logic unit that generates control voltages to control the bias currents of the oscillators, allowing the device to calculate environmental temperature based on the frequency ratio of oscillation signals from the oscillators, which are stable and independent of external clock signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional temperature sensing technique is used with external clock signal, then temperature sensing can be achieved, but the system requires external reference clock signal which increases cost and reduces reliability
Solution Approach 1:
The patent extracts the temperature sensing functionality from the external clock signal dependency, creating a self-contained sensing mechanism using only internal oscillators and logic circuits. The temperature sensing is achieved by comparing oscillation frequencies of two oscillators with different temperature characteristics, eliminating the need for external reference clocks.
Solution Approach 2:
The system performs self-service by using its own internal oscillators to generate the reference and measurement signals needed for temperature sensing. The arithmetic logic unit processes the oscillation signals internally, making the system autonomous and independent of external clock sources.
2Measurement precision
If external reference clock signal is used, then temperature sensing is enabled, but the system becomes dependent on external signals which may not be stable or available
Solution Approach 1:
The patent introduces oscillators as intermediary elements that convert temperature variations into measurable frequency changes. Instead of directly measuring temperature or relying on external clocks, the oscillators serve as mediators that translate thermal effects into electrical signals suitable for digital processing.
Solution Approach 2:
The system exploits parameter changes in oscillator frequency with temperature variations. By designing oscillators with different temperature coefficients, the system converts temperature changes into frequency ratio changes, enabling precise temperature measurement through frequency comparison rather than direct voltage or current measurement.
3Productivity
If temperature compensation is implemented, then circuit performance improves, but the system requires accurate temperature sensing which traditionally needs external references
Solution Approach 1:
The patent merges the temperature sensing function with the existing digital logic infrastructure of the integrated circuit. The arithmetic logic unit, already present for other processing tasks, is utilized to compute temperature from oscillator frequency ratios, combining multiple functions into a unified system that reduces overall complexity.
Solution Approach 2:
The oscillator-based temperature sensing system serves multiple functions: it provides temperature measurement for compensation, generates clock signals for digital logic, and can be used for frequency calibration. This multi-functionality reduces the need for separate dedicated temperature sensing circuits.
Data Source
AI summary
An on-chip temperature sensing device is disclosed. The disclosed on-chip temperature sensing device is capable of sensing an environmental temperature of the chip. The device comprises a reference generating circuit, a first oscillator, a second oscillator, and an arithmetic logic unit. The reference generating circuit is configured to generate a first control voltage to control the first oscillator and the second oscillator. The bias current of the first oscillator and the bias current of the second oscillator are both controlled by the first control voltage so that the bias current of the first oscillator is directly proportional the bias current of the second oscillator regardless the environmental temperature. The first oscillator generates a first oscillation signal, while the second oscillator generates a second oscillation signal. The arithmetic logic unit may calculate the environmental temperature according to the first oscillation signal and the second oscillation signal.