Schmitt Trigger Charging Assistance for Fast Low-Current Switching

Solution Overview

Problem

Schmitt triggers face challenges in achieving low static current consumption while maintaining high switching speeds, as improving switching speeds often results in increased area consumption and slower transitions due to the need for larger transistors to supply sufficient charging currents.

Innovation Solution

Incorporating a charging assistance circuit that provides supplemental charging currents during transitions, contributing no static current consumption between transitions, thus enabling fast operation with minimal additional area consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the Schmitt trigger uses larger transistors to supply sufficient charging currents for high switching speeds, then switching speed is improved, but area consumption increases

Engineering Contradiction:

Improveswitching speedVSAvoidarea consumption

Core Design Contradiction:

SpeedVSArea of stationary object

Solution Approach 1:

The charging current supply function is segmented into two parts: the main transistor branch for static operation and the parallel transistor branch for supplemental charging during transitions. This segmentation allows each branch to be optimized independently - the main branch uses smaller transistors for low static current, while the parallel branch provides high current only when needed for fast switching.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The parallel transistor branch operates periodically - activated only during transition periods when switching is needed, and deactivated during stable periods. This periodic operation provides high charging currents when required for fast switching while maintaining low static current consumption during stable states.

Inventive Principle:

Principle #19Periodic action

2Speed

If the Schmitt trigger uses larger transistors to supply sufficient charging currents, then switching speed is improved, but static current consumption increases

Engineering Contradiction:

Improveswitching speedVSAvoidstatic current consumption

Core Design Contradiction:

SpeedVSUse of energy by stationary object

Solution Approach 1:

The charging current supply function is segmented into two parts: the main transistor branch for static operation and the parallel transistor branch for supplemental charging during transitions. This segmentation allows each branch to be optimized independently - the main branch uses smaller transistors for low static current, while the parallel branch provides high current only when needed for fast switching.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The parallel transistor branch operates periodically - activated only during transition periods when switching is needed, and deactivated during stable periods. This periodic operation provides high charging currents when required for fast switching while maintaining low static current consumption during stable states.

Inventive Principle:

Principle #19Periodic action

3Use of energy by stationary object

If the Schmitt trigger is designed for low static current consumption, then static current consumption is reduced, but switching speed decreases

Engineering Contradiction:

Improvestatic current consumptionVSAvoidswitching speed

Core Design Contradiction:

Use of energy by stationary objectVSSpeed

Solution Approach 1:

The charging current supply function is segmented into two parts: the main transistor branch for static operation and the parallel transistor branch for supplemental charging during transitions. This segmentation allows each branch to be optimized independently - the main branch uses smaller transistors for low static current, while the parallel branch provides high current only when needed for fast switching.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The parallel transistor branch operates periodically - activated only during transition periods when switching is needed, and deactivated during stable periods. This periodic operation provides high charging currents when required for fast switching while maintaining low static current consumption during stable states.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11901900B2Schmitt trigger with current assistance circuit

Publication Date: 2024.02.13 STMICROELECTRONICS INT NV

AI summary

An integrated circuit includes an input pad and a Schmitt trigger coupled to the input pad. The Schmitt trigger includes a main PMOS branch that charges an intermediate node of the Schmitt trigger responsive to voltage transitions at the input node. The Schmitt trigger includes a charging assistance circuit that helps to rapidly charge the intermediate node of the Schmitt trigger. The charging assistance circuit includes a parallel PMOS branch in parallel with the main PMOS branch.