Sensor Device Series MOS Switch Capacitor Negative Feedback

Solution Overview

Problem

Conventional sensor devices fail to securely fix the output voltage to a power supply voltage or ground potential when the power supply line is disconnected, leading to incomplete detection of disconnection failures, especially in resistance type detection elements and CMOS process integrated circuits.

Innovation Solution

A series circuit of a MOS switch and a capacitor is incorporated in the negative feedback part of the output circuit, with a diode connected to the well electrode of the MOS switch, ensuring that the output voltage is fixed to either the power supply or ground potential upon disconnection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional output circuit configuration is used with resistance type detection elements, then the circuit can operate normally during normal conditions, but the output voltage cannot be fixed to power supply voltage or ground potential when the power supply line is disconnected

Engineering Contradiction:

Improvedetection accuracy of power supply disconnectionVSAvoidoutput circuit configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-configuring the output circuit with a MOS switch and capacitor in series, along with a diode connected to the well electrode. This configuration is established before power supply disconnection occurs, so that when disconnection happens, the circuit automatically fixes the output voltage to a defined potential without requiring additional detection circuitry. The MOS switch and capacitor are positioned to immediately affect the output voltage state upon power loss.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses the MOS switch and capacitor as intermediary elements between the power supply and the output terminal. When the power supply line is disconnected, these intermediary components ensure that the output voltage is pulled to a defined potential (either power supply voltage or ground potential) through the series circuit configuration and diode connection, enabling reliable failure detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If a CMOS amplifier circuit is used, then amplification performance is improved, but incomplete power supply causes voltage drop and incomplete voltage errors in the output

Engineering Contradiction:

Improveamplification accuracyVSAvoidoutput voltage stability during power supply disconnection

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-configuring the output circuit with a MOS switch and capacitor in series, along with a diode connected to the well electrode. This configuration is established before power supply disconnection occurs, so that when disconnection happens, the circuit automatically fixes the output voltage to a defined potential without requiring additional detection circuitry. The MOS switch and capacitor are positioned to immediately affect the output voltage state upon power loss.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses the MOS switch and capacitor as intermediary elements between the power supply and the output terminal. When the power supply line is disconnected, these intermediary components ensure that the output voltage is pulled to a defined potential (either power supply voltage or ground potential) through the series circuit configuration and diode connection, enabling reliable failure detection.

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

This configuration allows for reliable detection of power supply line disconnections, enabling fail-safe operation of the control system by maintaining the output voltage at a stable level, preventing incomplete voltage errors.

Implementation Method 1

a series circuit of a MOS switch (4) and a capacitor (2) is provided in a negative feedback part of an output circuit

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

an element acting as a diode (3) is connected to a well electrode of the MOS switch (4)

Methodology Applied

Scientific EffectDiode effect: Diode

Data Source

PatentUS9551735B2Sensor device with series circuit of MOS switch and capacitor

Publication Date: 2017.01.24 ASTEMO LTD

AI summary

In a related art sensor device, an output voltage of the sensor device is fixed not to a power supply voltage or a ground potential but to an intermediate potential upon disconnection of a power supply line or a ground line. A sensor device 1 is composed of: a detection element 8 whose voltage Vsen changes depending on a detected physical quantity; an output circuit configured by MOS switches 4 to 6, 7, 9, 10 and 12 to 17, capacitors 2, 11 and 18, an operational amplifier 19, a reference voltage source 20, and output NMOS transistor 21; a series circuit of the MOS switch 4 and the capacitor 2, the series circuit being arranged in a negative feedback part of the output circuit; and a diode 3 that connects a well electrode of the MOS switch 4 and a power supply terminal Vcc.