Shared Current Source Diode Biasing for Digital Bandgap Sensing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional temperature sensor designs face issues with diode mismatch and require accurate ADC reference voltage sources, necessitating improved methods for generating digital temperature values without these limitations.

Innovation Solution

An integrated circuit design using a single current source to bias diodes of different sizes, enabling analog-to-digital conversion of voltages across these diodes and performing arithmetic operations to generate digital bandgap and temperature values, eliminating the need for precise ADC reference voltages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a conventional temperature sensor design uses a single diode with voltage measurement, then the structure is simple, but diode mismatch occurs and accurate ADC reference voltage is required

Engineering Contradiction:

Improvestructure simplicityVSAvoidtemperature measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent combines multiple diodes with different sizes into a single temperature sensing system, where they share a common current source. By merging the measurement of multiple diodes and processing their voltage differences digitally, the system achieves temperature measurement without requiring accurate ADC reference voltages, thus resolving the contradiction between structural simplicity and measurement precision.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a digital processing circuit as an intermediary between the diodes and the output. This digital circuit performs arithmetic operations on the voltage values from multiple diodes to generate temperature readings and bandgap values, eliminating the need for precise analog reference voltages and reducing the impact of diode mismatch on measurement accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If multiple diodes with different sizes are used to reduce mismatch, then measurement accuracy improves, but device complexity increases

Engineering Contradiction:

Improvetemperature measurement accuracyVSAvoidcircuit structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes a single current source serve multiple functions by biasing multiple diodes of different sizes simultaneously. This universal current source approach allows the system to achieve temperature measurement, bandgap reference generation, and mismatch compensation without proportionally increasing circuit complexity, as one component performs multiple critical functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces complex analog reference voltage generation circuits with a simpler digital processing approach. Instead of using precise analog components to compensate for diode mismatch, the system uses digital arithmetic operations on voltage measurements, substituting complex analog mechanisms with simpler digital processing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If accurate ADC reference voltage source is used, then conversion accuracy improves, but cost and area increase

Engineering Contradiction:

ImproveADC conversion accuracyVSAvoidcost and area efficiency

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive, precise analog reference voltage sources with a simpler, more cost-effective digital processing approach. By using multiple diodes with a common current source and performing digital arithmetic on their voltage measurements, the system achieves accurate temperature readings without requiring costly high-precision ADC reference voltages, thus reducing both cost and area.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 design achieves low diode mismatch and reduces the need for accurate ADC reference voltages, providing a cost-effective and area-efficient temperature sensor with improved accuracy and reduced calibration requirements.

Implementation Method 1

The ADC is arranged to convert a first voltage across the first diode into a first diode voltage value, and convert a second voltage across the second diode into a second diode voltage value

Methodology Applied

Scientific EffectAnalog-to-digital conversion:

Data Source

PatentUS20250305887A1Integrated circuit of using same current source to bias diodes with different sizes for generating at least one of digital bandgap value and temperature value and associated signal processing method

Publication Date: 2025.10.02 AIROHA TECHNOLOGY CORPORATION

AI summary

An integrated circuit includes a current source, a diode device, a switch circuit, an analog-to-digital converter (ADC), and a processing circuit. The current source provides a reference current. The switch circuit enables the diode device to provide a first diode with a first size for receiving the reference current during a first interval, and enables the diode device to provide a second diode with a second size for receiving the reference current during a second interval. The ADC converts a first voltage across the first diode into a first diode voltage value, and converts a second voltage across the second diode into a second diode voltage value. The processing circuit performs an arithmetic operation upon the first diode voltage value and the second diode voltage value to generate a digital bandgap value.