I/O Cell Diode Array Clamping for High-Frequency Overvoltage Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrated circuits face challenges in protecting domains from overvoltages without disrupting high-frequency signal transmission, particularly in high-speed input/output cells.
Innovation Solution
An input/output cell with a diode array and control circuit that autonomously short-circuits diodes to limit voltage, using MOS transistors and resistors to manage overvoltages, and a capacitor to handle rapid voltage changes, ensuring protection without power supply intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diode array with high threshold voltage is used to protect the domain, then the domain is protected against overvoltages, but the leakage current increases
Solution Approach 1:
The protection circuit is segmented into multiple diodes connected in series, where each diode contributes a portion of the total threshold voltage. This segmentation allows the circuit to achieve high protection voltage while maintaining low leakage current, as each individual diode operates at its optimal low-voltage threshold.
Solution Approach 2:
The patent changes the electrical parameters of the protection circuit by using diodes with specific threshold voltage characteristics and configuring them in series. This parameter optimization allows the circuit to maintain low leakage current while providing sufficient overvoltage protection threshold.
2Reliability
If the number of diodes is increased to raise the threshold voltage, then the protection level increases, but the device complexity increases
Solution Approach 1:
Multiple diodes are merged in series configuration to achieve the desired threshold voltage. This merging approach provides high protection level while keeping the circuit structure simple and compact, as the diodes are integrated into the existing I/O cell architecture without requiring additional complex components.
3Reliability
If a protection circuit is added to limit overvoltages, then the domain is protected, but the transmission of high-frequency signals is restricted
Solution Approach 1:
The protection circuit exhibits local quality by having different operational characteristics for different voltage conditions. At normal operating voltages, the diodes are non-conductive and transparent to high-frequency signals. When overvoltage occurs, the diodes conduct locally to clamp the voltage, thus providing protection without affecting normal signal transmission.
Solution Approach 2:
The protection circuit is dynamic in its behavior, transitioning from a non-conductive state during normal operation to a conductive state during overvoltage events. This dynamic characteristic allows the circuit to protect against overvoltages while maintaining transparency to high-frequency signals during normal operation.
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
Effectively protects integrated circuit domains from overvoltages while maintaining high-frequency signal transmission by autonomously managing voltage levels and minimizing current leakage.
Implementation Method 1
An array of N diodes, for example, four diodes, connected in series between the second signal terminal and a cold power supply point, typically ground, the array having an overall threshold voltage greater than V1
Implementation Method 2
configured, in the presence of a voltage V2, for example, 5 volts or more, on the first signal terminal greater than the voltage V1, to automatically and autonomously short-circuit at least one of the diodes to limit the voltage on the second signal terminal to a value V3 less than V1
Implementation Method 3
a capacitor to handle rapid voltage changes
Data Source
AI summary
In embodiments, an integrated circuit is provided that includes an input/output cell having a first signal terminal and a second signal terminal connected to a domain and capable of withstanding a maximum voltage greater than the power supply voltage. The input/output cell further includes an array of N diodes coupled in series between the second signal terminal and a cold power supply point. The array has an overall threshold voltage greater than the maximum voltage. The integrated circuit further includes a control circuit connected between the first signal terminal and the array of diodes. The control circuit is configured, in the presence of a second voltage on the first signal terminal greater than the maximum voltage, to automatically and autonomously short-circuit at least one of the diodes in the array to limit the voltage on the second signal terminal to a third voltage less than the maximum voltage.