Oscillator-Based Temperature Sensor Without ADC Conversion

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Solution Overview

Problem

Conventional temperature sensors requiring Analog-to-Digital Convertors (ADCs) face issues such as space, weight, energy consumption, complexity, cost, and reduced accuracy due to ADC sensitivity to temperature, along with nonlinear resistor behavior.

Innovation Solution

A temperature sensor using a controlled oscillator that generates a digital temperature signal without an ADC, utilizing a bandgap circuit and controlled oscillators to produce temperature-dependent clock signals, which are counted to determine temperature in a binary format.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an ADC is used to convert temperature signal to digital format, then digital temperature output is achieved, but space requirements, weight, energy consumption, complexity, and cost increase

Engineering Contradiction:
Improvedigital temperature output accuracyVSAvoidcircuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and removes the ADC component from the temperature sensing system. Instead of using a separate ADC to convert the temperature signal, the invention integrates the conversion function directly into the oscillator circuit, where the temperature-dependent resonant frequency directly provides the digital output signal, eliminating the need for additional conversion hardware and reducing overall system complexity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The oscillator circuit serves multiple functions simultaneously: it acts as both the temperature sensing element (detecting temperature through resonant frequency changes) and the signal conversion device (directly outputting digital frequency signals). This multi-functionality eliminates the need for separate ADC components, reducing space, weight, and complexity while maintaining digital output capability

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If an ADC is used to convert temperature signal, then digital output is obtained, but energy consumption increases

Engineering Contradiction:
Improvedigital temperature measurement accuracyVSAvoidenergy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent removes the energy-consuming ADC component from the system. The temperature measurement is achieved through passive detection of resonant frequency changes in the oscillator, which naturally varies with temperature. This eliminates the need for active conversion processes that consume significant energy, resulting in a low-power temperature sensing solution

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If ADC is used for temperature conversion, then digital signal is generated, but ADC sensitivity to temperature reduces measurement accuracy

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoidADC temperature sensitivity
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the temperature-sensitive ADC component from the measurement chain and replaces it with a temperature-insensitive oscillator-based measurement system. The oscillator's resonant frequency is used directly as the measurement parameter, which is less susceptible to temperature drift effects compared to ADC conversion processes, thereby improving overall measurement accuracy

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent implements a feedback mechanism where the oscillator frequency is continuously monitored and used to adjust the measurement process. The frequency output directly reflects temperature changes through the resonant characteristics of the oscillator circuit, providing a self-correcting measurement system that compensates for environmental variations and maintains high accuracy without requiring temperature-compensated ADCs

Inventive Principle:
Principle #23Feedback

4Measurement precision

If conventional temperature sensor with resistor is used, then temperature signal is generated, but nonlinear behavior prevents linear measurement

Engineering Contradiction:
Improvetemperature signal generationVSAvoidmeasurement linearity
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent replaces the electrical resistor-based temperature sensing mechanism with a mechanical resonance-based oscillator system. The resonant frequency of the oscillator circuit exhibits linear behavior with temperature changes, unlike the nonlinear resistance-temperature relationship of conventional resistors. This substitution provides inherently linear temperature measurements without requiring complex linearization circuits or algorithms

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 approach eliminates the need for ADCs, reducing space, weight, and energy consumption while providing accurate, linear temperature measurement.

Implementation Method 1

a bandgap circuit configured to generate a first input signal that varies based on a temperature

Methodology Applied
Scientific EffectBandgap reference:

Implementation Method 2

one or more controlled oscillators including a first controlled oscillator configured to receive the first input signal and generate a first clock signal

Methodology Applied
Scientific EffectControlled oscillation:

Implementation Method 3

one or more counters including a first counter configured to receive the first clock signal from the clock generating circuit and a first enable signal for a first time period, wherein the first counter is further configured to generate at least a first count signal based at least on the first clock signal and the first enable signal

Methodology Applied
Scientific EffectFrequency counting:

Data Source

PatentEP4653831A1Temperature sensor using a controlled oscillator
Publication Date: 2025.11.26 STMICROELECTRONICS INT NV
  • EP4653831A1 patent drawingFigure 1
  • EP4653831A1 patent drawingFigure 2~3
  • EP4653831A1 patent drawingFigure 4~5

AI summary

Apparatuses, systems, and methods for temperature sensors are provided, including temperatures sensors using a controlled oscillator. An exemplary temperature sensor may comprise: a clock generating circuit comprising: a bandgap circuit to generate a first input signal that varies based on a temperature; a first controlled oscillator configured to receive the first input signal and generate a first clock signal; a first counter configured to receive the first clock signal and a first enable signal, wherein the first counter generates a first count signal based on the first clock signal and the first enable signal; a processor and a non-transitory memory including computer coded instructions, the computer coded instructions, with the processor, cause the processor to: determine the temperature based at least on the first count signal; and generate a temperature signal based at least on the temperature, wherein the temperature signal is a binary signal.