CMOS Contact Leakage Circuit for Substrate Current Blocking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
CMOS circuits in airbag ignition circuits are prone to malfunction due to the formation of parasitic bipolar transistors when external connections experience unintended potential drops, leading to substrate currents that disrupt the functioning of adjacent electronic components.
Innovation Solution
A device is implemented in the CMOS circuit to monitor the potential of external contacts and activate an electronic switch when it falls below a reference level, diverting current away from the substrate to prevent parasitic transistor activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If n-well regions are used to prevent substrate current in prior art, then substrate current prevention is achieved, but the CMOS circuit can only be implemented in a single n-well per chip
Solution Approach 1:
The invention segments the substrate current prevention function by introducing separate leakage circuit nodes (ABK) that are independent of the n-well structures. This allows multiple n-well regions to coexist without requiring a single comprehensive n-well, enabling flexible CMOS circuit implementations while preventing substrate current through dedicated leakage paths for each contact.
Solution Approach 2:
The invention introduces intermediary leakage circuit nodes (ABK) that mediate between the contact potentials (PDH, PDL) and the substrate. These intermediary nodes provide controlled current paths that prevent substrate current injection while allowing the CMOS circuit to use multiple n-well regions for different functional blocks.
2Reliability
If substrate current flows through parasitic bipolar lateral structure, then current injection into substrate occurs, but device reliability deteriorates
Solution Approach 1:
The invention applies preliminary anti-action by detecting contact potentials (PDH, PDL) and comparing them with reference values before substrate current can flow. When a contact potential is below or equal to a reference value (which is below substrate potential), the invention proactively connects the contact to a leakage circuit node (ABK) to drain current, preventing the harmful substrate current injection before it occurs.
Solution Approach 2:
The invention implements feedback by continuously monitoring contact potentials (PDH, PDL) and dynamically controlling the connection to leakage circuit nodes based on potential comparisons. This feedback mechanism ensures that substrate current prevention is activated only when necessary (when contact potential ≤ reference value), maintaining device reliability while avoiding unnecessary current paths.
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
Prevents substrate currents that cause malfunctions by maintaining the potential of monitored nodes above the reference level, ensuring the proper functioning of the CMOS circuit and preventing failures in airbag deployment.
Implementation Method 1
detect the potential of a contact (PDH, PDL) of the integrated CMOS circuit
Implementation Method 2
connect the contact (PDH, PDL) to a leakage circuit node (ABK) to drain the current
Data Source
Figure 1a
Figure 1b~1c
Figure 2
AI summary
The invention relates to various devices and methods for preventing the injection of a substrate current into the substrate sub of a CMOS circuit. For this purpose, the devices implement different methods for preventing such injection. They detect the potential of a contact (PDH, PDL) of the integrated CMOS circuit, compare the value of the detected potential with a reference value, and connect the contact (PDH, PDL) to a leakage circuit node (ABK) to drain the current, so that it does not flow through the parasitic bipolar lateral structure, i.e., not into the substrate. The leakage circuit node can be connected, for example, to the reference potential line (GND) or to another line that has a higher potential than that of the reference potential line (GND). This electrical connection is then activated or...initiated when the potential value of the contact (PDH, PDL) is below or equal to a reference value, where this reference value is below the potential value of the substrate Sub and/or below the potential value of the reference potential line (GND) or the other line mentioned above.