Cross-Coupled Capacitor Cell Structure for IC Noise and Latch-Up
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrated circuits (ICs) face significant voltage noise issues due to transient currents, which can degrade noise margins and lead to circuit malfunction, despite the use of filtering or de-coupling capacitors.
Innovation Solution
The implementation of a cross-coupled de-coupling structure using PMOS and NMOS transistors, which form a capacitor cell that provides MOS capacitance and series channel-resistance to enhance electrostatic discharge (ESD) protection and reduce gate leakage current, while also forming low resistance paths to prevent latch-up and improve immunity to noise-induced latch-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filtering or de-coupling capacitors are used between power supply lines, then voltage fluctuations are reduced, but device complexity increases
Solution Approach 1:
The patent combines multiple capacitor cells with different capacitance values into a single integrated de-coupling structure. The first capacitor cell (first capacitance value) and second capacitor cell (second capacitance value) are merged to provide multi-frequency noise filtering, reducing the need for separate capacitor components and simplifying the overall device architecture while maintaining effective voltage fluctuation reduction.
Solution Approach 2:
The de-coupling capacitor structure performs multiple functions simultaneously: it provides charge reservoir functionality for transient current suppression, filters voltage noise across different frequency ranges (through dual capacitance values), and integrates ESD protection and latch-up immunity features. This multi-functional design reduces the need for separate dedicated components for each function.
2Reliability
If de-coupling capacitors are added to prevent momentary voltage drops, then power supply stability is improved, but manufacturing complexity increases
Solution Approach 1:
The de-coupling capacitor is divided into multiple discrete capacitor cells (first capacitor cell with first capacitance value, second capacitor cell with second capacitance value), each optimized for specific frequency ranges or functional requirements. This segmentation allows for standardized fabrication of individual cells using常规 CMOS processes, while the modular structure simplifies integration and testing compared to a single complex capacitor design.
Solution Approach 2:
The patent utilizes different capacitance values (first capacitance value and second capacitance value) to address different aspects of power supply stability. By varying the capacitance parameter across multiple cells, the structure achieves broad-spectrum noise filtering and transient response optimization without requiring complex fabrication processes, as capacitance variation can be achieved through standard design parameter adjustment in CMOS technology.
3Reliability
If cross-coupled de-coupling structure with PMOS and NMOS transistors is implemented, then ESD protection and latch-up immunity are enhanced, but device complexity increases
Solution Approach 1:
The patent merges the de-coupling capacitor functionality with ESD protection and latch-up immunity features into a single integrated structure. The cross-coupled PMOS and NMOS transistors are combined with the capacitor cells to form a unified circuit block that simultaneously provides charge reservoir functionality, electrostatic discharge protection, and latch-up prevention, eliminating the need for separate protection circuits.
Solution Approach 2:
The cross-coupled transistor configuration serves multiple protective functions: it provides ESD protection by clamping voltage transients, prevents latch-up through controlled current paths, and maintains de-coupling functionality. This multi-functional design achieves comprehensive protection without requiring separate dedicated circuits for each protection mechanism, thereby reducing overall device complexity despite the sophisticated transistor arrangement.
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 reduces power supply noise, enhances ESD protection, and increases latch-up immunity, thereby improving the reliability and stability of ICs by providing robustness against high current conduction triggered by noise sources.
Implementation Method 1
The capacitor cell provides the MOS capacitance and the series channel-resistance
Implementation Method 2
the capacitor cell provides MOS capacitance and series channel-resistance to enhance electrostatic discharge (ESD) protection
Implementation Method 3
forming low resistance paths to prevent latch-up and improve immunity to noise-induced latch-up
Data Source
AI summary
Capacitor cells are provided. A first PMOS transistor is coupled between a power supply and a first node, and has a gate directly connected to a second node. A first NMOS transistor is coupled between a ground and the second node, and has a gate directly connected to the first node. A second PMOS transistor is coupled between the second node and the power supply, and has a gate directly connected to the second node. A second NMOS transistor is coupled between the first node and the ground, and has a gate directly connected to the first node. Sources of the first and second NMOS transistors share an N+ doped region in the P-type well region. The first NMOS transistor is disposed between the second NMOS transistor and the first and second PMOS transistors. Source of the first PMOS transistor is directly connected to the power supply.