Schmitt Trigger Inverter Circuit With Shoot-Through Current Limiting

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Solution Overview

Problem

The existing Schmitt trigger inverter circuits experience unnecessary current consumption due to shoot-through voltage, which is problematic in the context of reducing power consumption.

Innovation Solution

Incorporating a CMOS inverter with a first transistor and a current limiting element in series, along with additional transistors and current limiting elements, to limit the current flow and suppress shoot-through voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transistors MN2 and MN3 are both turned on during switching transitions, then the Schmitt trigger inverter circuit can achieve threshold voltage switching functionality, but shoot-through voltage causes unnecessary current consumption

Engineering Contradiction:

Improvethreshold voltage switching functionalityVSAvoidcurrent consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

A diode is introduced as an intermediary element between transistor MN3 and ground. This diode acts as a mediator that prevents direct current flow from VCC to ground when both MN2 and MN3 are on, thereby eliminating shoot-through current while preserving the threshold voltage switching functionality of the Schmitt trigger inverter circuit.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the potentially harmful shoot-through current condition (when both MN2 and MN3 are on) into a beneficial state by using the diode to redirect the current flow. The diode allows the circuit to utilize the simultaneous conduction state for proper threshold switching while preventing energy waste through the harmful direct current path.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Stability of the object's composition

If transistor MN3 is kept on to maintain output at high level, then output stability is improved, but power consumption increases due to continuous current flow

Engineering Contradiction:

Improveoutput stabilityVSAvoidpower consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The diode serves as an intermediary that enables transistor MN3 to remain on for output stability while preventing continuous current flow to ground. The diode blocks the direct current path when MN2 is off, allowing MN3 to maintain the output at high level without causing continuous power consumption.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10979035B2Schmitt trigger inverter circuit

Publication Date: 2021.04.13 FUJI ELECTRIC CO LTD

AI summary

To suppress the generation of a shoot-through current in a Schmitt trigger inverter circuit, a Schmitt trigger inverter circuit SINVa includes: a CMOS inverter CI having the input and output connected to the input and output of the Schmitt trigger inverter circuit, respectively; a first transistor MN3 having the gate connected to the output of the CMOS inverter; and a first current limiting element DEP1 connected to the first transistor in series.