Passive Edge Detection Circuit With Threshold Noise Rejection

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Solution Overview

Problem

Existing edge detection circuits in analogue and digital systems face challenges due to the lack of mature p-channel devices, particularly in III-nitride compound semiconductor materials, leading to reduced bandwidth and increased false triggering events from noise signals.

Innovation Solution

The development of edge detection circuits that utilize a passive differentiator circuit and a comparator circuit without operational amplifiers, allowing for the detection of rising and falling edges without p-channel devices, and incorporating a voltage reference circuit to reduce false triggering from noise signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If operational amplifiers are used in edge detection circuits, then the circuit can detect edges effectively, but the circuit requires p-channel devices which are not technologically mature in III-nitride compounds, reducing manufacturing feasibility

Engineering Contradiction:

Improveedge detection capabilityVSAvoidmanufacturing feasibility in III-nitride compounds

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and removes the operational amplifier component from the edge detection circuit, replacing it with a passive differentiator circuit consisting of a capacitor and resistor. This extraction eliminates the requirement for p-channel devices while preserving the edge detection functionality, thereby resolving the manufacturing feasibility issue in III-nitride compound technologies.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the active operational amplifier system with a passive RC differentiator system. This substitution replaces the need for complex active components with simple passive components that are compatible with III-nitride semiconductor manufacturing processes, maintaining edge detection capability while improving manufacturability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If real differentiator circuits with negative feedback resistors are used, then high frequency noise is rejected, but the bandwidth is reduced as higher frequency input signals fail to trigger output

Engineering Contradiction:

Improvenoise rejection capabilityVSAvoidbandwidth

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent changes the circuit parameters by using a passive differentiator with carefully selected RC time constants instead of a real differentiator with negative feedback. By optimizing the capacitor and resistor values, the circuit achieves noise rejection for high-frequency signals while maintaining sufficient bandwidth to detect relevant edge transitions, resolving the contradiction between noise rejection and bandwidth.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If passive differentiator circuits without operational amplifiers are used, then the circuit can be manufactured with III-nitride compounds, but the circuit may be more susceptible to false triggering from noise signals

Engineering Contradiction:

Improvecompatibility with III-nitride compoundsVSAvoidfalse triggering resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces a threshold voltage level as an intermediary element in the passive differentiator circuit. This threshold acts as a mediator that filters out small noise signals below the threshold level while allowing genuine edge transitions to trigger the output, thereby providing false triggering resistance without requiring operational amplifiers or p-channel devices.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

These circuits effectively detect edges in signals with reduced false triggering and improved noise immunity, suitable for integration with III-nitride compound semiconductor materials, enhancing the performance of edge detection in analogue and digital systems.

Implementation Method 1

a passive differentiator circuit configured to receive an input and provide a differentiator output signal that is proportional to the rate of change of the input

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

a comparator circuit operably connected to a voltage source, wherein the comparator circuit is configured to: receive the differentiator output signal; compare the differentiator output signal to a threshold voltage

Methodology Applied

Scientific EffectVoltage comparison:

Data Source

PatentUS11784637B1Edge detection circuit

Publication Date: 2023.10.10 CAMBRIDGE GAN DEVICES LIMITED

AI summary

The present disclosure relates to an edge detection circuit configured to receive an input signal comprising one or more falling or falling edges and provide an output signal comprising pulses or spikes corresponding to the one or more rising or falling edges. The edge detection circuit comprises a passive differentiator circuit configured to receive an input and provide a differentiator output signal that that is proportional to the rate of change of the input, and a comparator circuit operably connected to a voltage source. The comparator circuit is configured to receive the differentiator output signal, compare the differentiator output signal to a threshold voltage; and output a pulse or spike signal based on the comparison to the threshold voltage.