Overvoltage Switch Leakage Current Compensation Circuit
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Solution Overview
Problem
Integrated circuits (ICs) are vulnerable to overstress events such as electrostatic discharge (ESD) and electromagnetic interference (EMI), which can cause damage due to overvoltage conditions and high power dissipation, leading to issues like gate oxide punch-through, junction damage, and latch-up, necessitating protection without impacting performance.
Innovation Solution
An integrated circuit with a protection device featuring a first and second semiconductor well of opposite conductivity types, along with a leakage current compensation circuit that controls the voltage level of the second well based on the input node's voltage to inhibit leakage current, thereby reducing the impact of overstress events while maintaining minimal performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection device is added to protect against overstress events, then reliability is improved, but leakage current increases causing performance degradation
Solution Approach 1:
A compensation circuit is introduced as an intermediary element between the protection device and the protected circuit. This compensation circuit actively counteracts the harmful leakage current by generating an equal and opposite current, thereby eliminating the net harmful effect while preserving the protection function
Solution Approach 2:
The invention dynamically adjusts the compensation current parameter based on the operating conditions. By monitoring the voltage across the protection device and adjusting the compensation circuit accordingly, the system maintains optimal cancellation of leakage current across different operating states
2Reliability
If a protection device is used to prevent damage from overstress, then reliability is improved, but input bias current increases affecting precision amplifier performance
Solution Approach 1:
The compensation circuit acts as an intermediary that isolates the precision amplifier from the harmful effects of the protection device. By inserting this active compensation stage between the amplifier and protection device, the amplifier sees a virtual ground that eliminates the impact of leakage and bias currents on its performance
3Reliability
If conventional protection devices are implemented, then overstress protection is provided, but leakage current becomes significant at high temperatures
Solution Approach 1:
The compensation circuit implements a feedback mechanism that continuously monitors the voltage across the protection device and adjusts the compensation current in real-time. This feedback control ensures that the compensation current accurately tracks and cancels the temperature-dependent leakage current, maintaining effective compensation even as temperature varies
Solution Approach 2:
The active compensation circuit serves as a temperature-insensitive intermediary that counteracts the temperature-sensitive leakage current of the protection device, effectively decoupling the system's overall temperature dependence from the protection device's inherent thermal characteristics
Data Source
AI summary
Apparatus and methods for overvoltage switches with active leakage current compensation are provided. In certain configurations, an IC includes an input node and a protection device or overvoltage switch electrically connected to the input node. The protection device includes a first well and a second well. The second well is positioned adjacent to the first well and has a conductivity type opposite that of the first well. Additionally, a first terminal of the protection device is electrically connected to the first well and to the input node of the IC. The protection device further includes a leakage current compensation circuit that is used to control a voltage level of the second well based on a voltage level of the first terminal to inhibit a leakage current of the first terminal of the protection device.