PNP Bipolar Transistor ESD Protection Circuit
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Solution Overview
Problem
Conventional semiconductor devices face challenges in achieving effective electrostatic discharge (ESD) protection without increasing chip size and cost, particularly due to limitations in ESD resistance for both high-potential and low-potential power supply terminals, leading to enlarged chip sizes and higher production costs.
Innovation Solution
The semiconductor device incorporates three types of PNP bipolar transistors with specific connections to input/output terminals and power supply terminals, along with parasitic resistances and diodes, to provide comprehensive ESD protection without enlarging the layout size of the protection circuit, utilizing inverse conductivity diffusion layers and insulating layers to separate transistor components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional PNP bipolar transistor protection circuit is used, then ESD protection is provided, but the chip size increases and cost increases
Solution Approach 1:
The patent combines multiple protection functions into a single integrated circuit block. The protection circuit includes a first PNP bipolar transistor for protecting against positive ESD surges, a second PNP bipolar transistor for protecting against negative ESD surges, and a third PNP bipolar transistor for protecting the power supply terminal, all integrated within one chip area. This merging of multiple protection mechanisms into a unified structure provides comprehensive ESD protection while minimizing chip size expansion.
Solution Approach 2:
The protection circuit is designed to provide multiple protection functions simultaneously. The first and second PNP bipolar transistors protect the input/output terminal against both positive and negative ESD surges, while the third PNP bipolar transistor protects the power supply terminal. This multi-functional design ensures comprehensive ESD protection across all critical points without requiring separate protection circuits for each function, thereby reducing overall chip size.
2Reliability
If additional protection circuits are added to improve ESD resistance, then reliability improves, but device complexity increases
Solution Approach 1:
The patent merges multiple protection functions into a single integrated circuit block. The protection circuit includes a first PNP bipolar transistor for protecting against positive ESD surges, a second PNP bipolar transistor for protecting against negative ESD surges, and a third PNP bipolar transistor for protecting the power supply terminal, all integrated within one chip area. This merging of multiple protection mechanisms into a unified structure provides comprehensive ESD protection while minimizing chip size expansion.
Solution Approach 2:
The patent utilizes the inherent parameters of PNP bipolar transistors, specifically their breakdown voltage and current gain characteristics, to provide ESD protection. By selecting appropriate transistor parameters and configuring their connections, the circuit achieves effective ESD protection without requiring complex additional components. The parasitic diodes and resistances inherent in the transistor structures are leveraged to simplify the overall circuit design.
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 achieves high ESD resistance across all modes without requiring additional protection circuits, resulting in lower costs and smaller chip sizes while ensuring reliable protection against ESD surges.
Implementation Method 1
by means of a breakdown operation of the parasitic diode 107 of the PNP type bipolar transistor 110, current flows from the emitter (high concentration P type emitter 211) connected to the input/output terminal 102, into the base (high concentration N type base 212) connected to the high-potential power supply terminal 103
Implementation Method 2
by means of a snap-back operation of the PNP type bipolar transistor 110, current flows from the emitter (high concentration P type emitter 211) connected to the input/output terminal 102, into the collector (high concentration P type collector 213) connected to the low-potential power supply terminal 104
Data Source
AI summary
In a protection circuit of an input/output terminal I/O, three types of PNP bipolar transistors are included. In a first PNP type bipolar transistor 10A, the emitter thereof is connected to the input/output terminal I/O, the base thereof is connected to a high-potential power supply terminal VDD, and the collector thereof is connected to a low-potential power supply terminal VSS. In a second PNP type bipolar transistor 10B, the emitter thereof is connected to the input/output terminal I/O, and the base and the collector thereof are connected to the high-potential power supply terminal VDD. In a third PNP type bipolar transistor 10C, the emitter thereof is connected to the low-potential power supply terminal VSS, and the base and the collector thereof are connected to the high-potential power supply terminal VDD.