Single-Comparator Voltage Threshold Detection With Hysteresis

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Solution Overview

Problem

Existing electronic circuits face challenges in comparing an input voltage against multiple reference voltages due to the need for multiple comparators, which is not desirable when area on a die/chip is limited.

Innovation Solution

A single comparator-based comparison circuit is used to compare an input voltage against multiple reference voltages, utilizing branch circuits and a mode selector to determine the specific reference voltage being compared, with hysteresis for stable detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple comparators are used to compare input voltage against multiple reference voltages, then comparison accuracy and reliability are improved, but device area and complexity increase

Engineering Contradiction:

Improvevoltage comparison reliabilityVSAvoiddie area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

A single comparator circuit is designed to perform multiple comparison functions by sequentially comparing the input voltage against different reference voltages stored in a reference voltage register. The comparator is controlled by a counter and decoder to select different reference voltages from the register, allowing one comparator to replace multiple comparators while maintaining comparison reliability across multiple voltage thresholds.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Multiple comparison operations are merged into a single comparator by combining the reference voltage storage (register), selection logic (decoder), and comparison function into one integrated circuit block. This merging reduces the total component count and die area while preserving the ability to perform multiple voltage threshold comparisons.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If multiple comparators are used to compare input voltage against multiple reference voltages, then comparison coverage is improved, but device complexity increases

Engineering Contradiction:

Improvevoltage level detection capabilityVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The single comparator circuit achieves multi-functionality by using a reference voltage register that can store multiple reference voltages and a decoder that selects which reference voltage to compare against based on the counter value. This allows the circuit to detect multiple voltage levels (e.g., under-voltage, over-voltage conditions) using one comparator instead of requiring separate comparators for each threshold.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The circuit dynamically switches between different reference voltages during operation using a counter that increments through different values, with each value corresponding to a specific reference voltage selection. This dynamic switching allows the single comparator to sequentially perform multiple comparison tasks that would otherwise require multiple static comparators.

Inventive Principle:

Principle #15Dynamics

3Area of stationary object

If a single comparator is used to compare input voltage against multiple reference voltages, then area and power consumption are reduced, but detection stability may worsen

Engineering Contradiction:

Improvedie areaVSAvoiddetection stability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The circuit incorporates hysteresis feedback by connecting the comparator output back to its positive input terminal through a feedback network. This hysteresis creates different threshold levels for rising and falling voltage transitions, preventing oscillation and false triggering when the input voltage is near the comparison threshold. This feedback mechanism maintains detection stability and reliability even though only a single comparator is used.

Inventive Principle:

Principle #23Feedback

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 efficiently compares input voltages against multiple reference voltages with reduced power consumption and area, providing stable detection of under-voltage and over-voltage conditions.

Implementation Method 1

A comparator is a circuit which generates a first logic value if a comparator input voltage is greater than a comparator reference voltage, and a second logic value otherwise

Methodology Applied

Scientific EffectVoltage comparison:

Implementation Method 2

with hysteresis for stable detection

Methodology Applied

Scientific EffectHysteresis: Hysteresis

Data Source

PatentUS20260019084A1Single comparator based comparison of an input voltage against multiple reference voltages

Publication Date: 2026.01.15 NINGBO AURA SEMICON CO LTD

AI summary

According to an aspect, a comparison circuit includes (A) a comparator to compare a comparator input with a comparator reference and generate a comparator output; (B) a mode selector to generate as a mode value, a first logic value if an input voltage (provided at a first node) is below a mid-voltage and a second logic value otherwise; (C) a first branch (coupled between the first node and a second node) to generate a first voltage drop approximately equaling a difference between a first reference voltage and the comparator reference; (D) a second branch (coupled between the first node and a second node) to generate a second voltage drop approximately equaling a difference between a second reference voltage and the comparator reference; and (E) a selection circuit to couple one of the second node or the third node as the comparator input according to the mode value.