Bandgap Reference Circuit With Substrate Current Suppression

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Solution Overview

Problem

Unnecessary substrate current is generated in reference voltage generation circuits, leading to malfunctions, particularly in semiconductor devices with avalanche photodiodes, due to parasitic transistors and fluctuations in substrate potential.

Innovation Solution

A substrate current suppression circuit is introduced, comprising transistors with opposite polarities and a fixed voltage line to suppress substrate current, integrated with a bandgap reference circuit to stabilize reference voltages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a reference voltage generation circuit is formed in a semiconductor substrate, then reference voltage generation function is achieved, but unnecessary substrate current is generated causing circuit malfunction

Engineering Contradiction:

Improvecircuit reliabilityVSAvoidsubstrate current

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and removes the harmful substrate current from the system by introducing a suppression circuit that specifically targets and eliminates the unwanted current path, allowing the reference voltage generation circuit to function without the harmful side effect

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The suppression circuit acts as an intermediary element between the reference voltage generation circuit and the substrate, mediating the current flow to prevent harmful substrate current while maintaining the necessary voltage generation function

Inventive Principle:

Principle #24Intermediary (Mediator)

2Power

If high negative voltage is applied to the substrate, then substrate current increases, but circuit malfunction occurs

Engineering Contradiction:

Improvesubstrate voltageVSAvoidcircuit reliability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The suppression circuit is designed to preemptively counteract the harmful effects of high negative voltage by establishing a protective mechanism that activates when such voltage conditions occur, preventing substrate current increase before it can cause damage

Inventive Principle:

Principle #9Preliminary anti-action

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

The solution effectively suppresses unnecessary substrate current, stabilizing reference voltages and preventing malfunctions in semiconductor devices, especially those with avalanche photodiodes.

Implementation Method 1

a circuit that generates a reference voltage utilizing a difference in band gap between two diodes of the same type or two bipolar transistors of the same type

Methodology Applied

Scientific EffectBand gap difference:

Implementation Method 2

The fixed voltage is a voltage higher than the base voltage of the third transistor and the fourth transistor when the first polarity is p type, and is a voltage lower than the base voltage when the first polarity is n type

Methodology Applied

Scientific EffectParasitic transistor blocking:

Data Source

PatentUS12393220B2Substrate current suppression circuit, reference voltage generation circuit, and semiconductor device

Publication Date: 2025.08.19 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A substrate current suppression circuit includes: a fixed voltage line that supplies a fixed voltage to the collectors of the third and fourth transistors. The fixed voltage is a voltage higher than the base voltage of the third and fourth transistors when the first polarity is p type, and is a voltage lower than the base voltage when the first polarity is n type.