Semiconductor ESD Protection Circuit With Feedback Clamp Control
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Solution Overview
Problem
Voltage-triggered electrostatic protection circuits in semiconductor devices face challenges in achieving a suitable margin for discharge start voltage relative to power supply voltage and clamp voltage relative to breakdown withstand voltage, leading to potential operational hindrances or circuit breakdown.
Innovation Solution
Incorporating a second amplifier circuit that feedback-amplifies detection signals to enhance the discharge capability of the discharge element, allowing for a higher discharge start voltage while ensuring the clamp voltage remains within safe limits, thereby aligning the margins of discharge start voltage and clamp voltage with the power supply and breakdown withstand voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the discharge start voltage is lowered to protect against ESD noise, then the protection capability is improved, but the internal circuit operation may be hindered due to voltage conflict with power supply voltage
Solution Approach 1:
The patent divides the discharge element control into two independent triggering paths: a voltage detection circuit that monitors voltage levels and a transient detection circuit that detects rapid voltage changes. This segmentation allows the discharge element to be activated by either ESD conditions (detected by transient circuit) or EMS conditions (detected by voltage circuit) without conflict, resolving the contradiction between protection capability and operational safety.
Solution Approach 2:
The patent employs dynamic control of the discharge element through two separate detection circuits that respond to different noise characteristics. The transient detection circuit responds to sharp ESD pulses while the voltage detection circuit responds to slower EMS variations. This dynamic, multi-path approach enables the system to adapt its discharge timing and threshold based on the specific noise type, preventing operational hindrance while maintaining protection capability.
2Ease of operation
If the discharge start voltage is raised to avoid operational hindrance, then the internal circuit operation is protected, but the clamp voltage may exceed the breakdown withstand voltage during discharge
Solution Approach 1:
The patent segments the detection function into two specialized circuits: one for voltage level detection and one for transient pulse detection. This allows the system to set appropriate discharge thresholds for each noise type independently, ensuring that discharge starts at safe voltage levels for EMS noise while maintaining low clamp voltage for ESD noise through the transient circuit's rapid response.
Solution Approach 2:
The voltage detection circuit continuously monitors the voltage level and provides feedback control to the discharge element. When the voltage reaches a predetermined threshold, the circuit triggers discharge to clamp the voltage, preventing it from exceeding the breakdown withstand voltage. This feedback mechanism ensures circuit safety while maintaining operational margins.
3Adaptability or versatility
If a voltage-triggered protection circuit is used to protect against EMS noise, then the protection coverage is improved, but the discharge element cannot be driven when ESD noise occurs with sharp rise and narrow pulse width
Solution Approach 1:
The patent creates a universal protection system where the discharge element can be triggered by multiple types of noise conditions through two separate detection circuits. The voltage detection circuit handles EMS noise with slow rise, while the transient detection circuit handles ESD noise with sharp rise and narrow pulse width. This multi-functional approach ensures comprehensive protection coverage across different noise types without sacrificing reliability for any specific condition.
Solution Approach 2:
The protection system is segmented into two specialized detection paths: voltage detection for EMS noise and transient detection for ESD noise. Each detection circuit is optimized for its specific noise type, allowing the discharge element to respond appropriately to both ESD and EMS conditions. This segmentation resolves the contradiction by enabling the system to handle multiple noise types effectively.
Data Source
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.