Charge-Injection Temperature Sensor for Compact Low-Power Design
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Solution Overview
Problem
State-of-the-art temperature sensors are not compact and often based on static current-consuming elements, which negatively affects their energy efficiency.
Innovation Solution
A temperature sensor utilizing a charge-injection cell arrangement with a few transistors and small capacitors, operating dynamically to achieve high energy efficiency and compactness, comprising pull-down and pull-up charge-injection cells that transfer temperature-dependent charge to output capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If state-of-the-art temperature sensors are used, then temperature measurement capability is achieved, but device area and power consumption increase
Solution Approach 1:
The patent applies dynamic operation principles by using charge-injection cells that are activated only during measurement cycles rather than continuous operation. The circuit switches between different states (charging, discharging, measuring) to achieve temperature sensing with minimal active components, reducing the required device area while maintaining measurement capability.
Solution Approach 2:
The invention changes the operational parameters from static current-consuming modes to dynamic charge-injection modes. By utilizing capacitive charge transfer instead of continuous current flow, the device achieves temperature measurement with significantly reduced area requirements and improved energy efficiency.
2Measurement precision
If state-of-the-art temperature sensors are used, then temperature measurement capability is achieved, but energy efficiency deteriorates due to static current consumption
Solution Approach 1:
The patent implements periodic charge-injection cycles where the temperature sensor operates in discrete measurement intervals rather than continuously. The charge-injection cells are activated periodically to transfer charge proportional to temperature, with the circuit returning to a low-power state between measurements, thereby dramatically improving energy efficiency.
Solution Approach 2:
The charge-injection circuit uses the temperature-dependent characteristics of the transistors themselves to generate the measurement signal without requiring continuous external power for signal generation. The circuit leverages its own operational characteristics (threshold voltage variations with temperature) to perform the sensing function efficiently.
3Area of stationary object
If compact temperature sensor design is implemented, then device area is reduced, but manufacturing precision requirements increase due to minimal transistor arrangements
Solution Approach 1:
The patent employs local quality optimization by carefully designing the charge-injection circuit to minimize the impact of transistor mismatches. Specific transistors are positioned and sized to exploit matching characteristics, and the charge-injection mechanism is designed to be less sensitive to parameter variations, allowing compact implementation while managing manufacturing tolerances.
Solution Approach 2:
The measurement methodology incorporates feedback mechanisms where the charge transfer amount is measured and processed to compensate for minor transistor mismatches. By measuring the actual charge transferred and using this information in the temperature calculation, the system can achieve accurate results even with minimal transistor arrangements that have inherent manufacturing variations.
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
The solution provides a highly efficient and compact temperature sensor with low power consumption, capable of accurately measuring temperature with minimal transistor mismatch and supply voltage independence.
Implementation Method 1
a first charge-injection cell configured to transfer charge from a first source capacitor to a first output capacitor in response to a first enable pulse and a second charge-injection cell configured to transfer charge from a second source capacitor to a second output capacitor
Data Source
AI summary
A charge-injection cell-based temperature sensor (1) is provided. The temperature sensor (1) comprises one or more charge-injection cells (3, 9). The temperature sensor (1) is configured to allow charge to be transferred from one or more source capacitors (Cs,n, Cs,p) to one or more output capacitors (Cout,n, Cout,p) once transistors (M1, M2, M3, M4) of the charge-injection cells are enabled to allow current to flow through them. The temperature sensor (1) further comprises a temperature sensing unit (7) configured to determine one or more charge-injection cell output voltage values to thereby derive a temperature value from the one or more first charge-injection cell output voltage values.