ESD Protection Circuit With Dual Amplifiers for Clamp Voltage Control
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Solution Overview
Problem
Existing electrostatic protection circuits in semiconductor devices struggle to simultaneously maintain a discharge start voltage that is higher than the power supply voltage while ensuring the clamp voltage does not exceed the breakdown withstand voltage of the internal circuit, particularly when facing ESD and EMS noise.
Innovation Solution
The introduction of a second amplifier circuit in the electrostatic protection circuit, which operates in conjunction with a first amplifier circuit to adjust the discharge start voltage and clamp voltage, ensuring compatibility with the power supply voltage and breakdown withstand voltage by separately controlling the operation of both amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the discharge start voltage is set lower than the power supply voltage to ensure the internal circuit operates normally during discharge, then the ease of operation is improved, but the reliability deteriorates because the internal circuit may be damaged by excessive discharge current
Solution Approach 1:
The discharge element's ON resistance is dynamically controlled by adjusting the drive signal voltage. The control circuit varies the gate voltage of the discharge element based on the detected voltage level, enabling the resistance to adapt between different states. This dynamic control allows the discharge start voltage to be higher than the power supply voltage while maintaining safe discharge current levels, resolving the contradiction between ease of operation and reliability
2Reliability
If the discharge start voltage is set higher than the power supply voltage to improve protection effectiveness, then the reliability is improved, but the ease of operation deteriorates because the internal circuit operation may be hindered during discharge
Solution Approach 1:
The system dynamically adjusts the discharge element's ON resistance based on the voltage detection results. When voltage exceeds the power supply voltage, the control circuit increases the drive signal to lower the ON resistance, enabling effective discharge protection. The dynamic control ensures that despite the higher discharge start voltage, the internal circuit operates normally by maintaining appropriate current levels through real-time resistance adjustment
3Device complexity
If a single amplifier circuit is used to detect voltage and drive the discharge element, then the device complexity is reduced, but the ability to independently control discharge start voltage and clamp voltage deteriorates
Solution Approach 1:
The voltage detection and control function is divided into two independent amplifier circuits: a first amplifier for detecting voltage and generating a first drive signal, and a second amplifier for detecting voltage and generating a second drive signal. This segmentation allows independent optimization of each amplifier's parameters, enabling separate control of discharge start voltage and clamp voltage while maintaining manageable overall circuit complexity
Data Source
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AI summary
The present invention provides both a margin of a discharge start voltage with respect to a power supply voltage and a margin of a clamp voltage with respect to a breakdown withstand voltage of an internal circuit. The semiconductor device according to the embodiment includes a first amplifier circuit for amplifying a detection signal and outputting a drive signa, a second amplifier circuit for feedback-amplifying the detection signal to be input to the first amplifier circuit, and a discharge element whose discharge capability changed according to the magnitude of the drive signal.