Integrated Clamp Circuit for Transistor Voltage Spike Protection

Solution Overview

Problem

Power transistor devices are vulnerable to voltage spikes during transitions between on and off states, which can exceed their voltage blocking capability, leading to potential damage or degradation, and designing for higher blocking capability increases conduction losses and costs.

Innovation Solution

An electronic circuit with a first transistor device and a clamping circuit, where a second transistor device with a parallel load path is controlled by a drive circuit to prevent voltage spikes by clamping the load path voltage within a threshold, integrating both devices in a semiconductor die.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the voltage blocking capability of the transistor device is increased to withstand voltage spikes, then the reliability of the transistor device is improved, but the conduction losses and manufacturing cost increase

Engineering Contradiction:

Improvevoltage blocking capabilityVSAvoidconduction losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The protection function is segmented from the main transistor device by introducing a separate clamping circuit with a second transistor device. This secondary device specifically handles voltage spike protection, allowing the first transistor device to be optimized for low conduction losses without needing excessive voltage blocking capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The clamping circuit acts as an intermediary protective layer between the voltage spikes and the first transistor device. When voltage spikes occur during switching transitions, the clamping circuit activates to limit the voltage, preventing direct exposure of the main transistor device to damaging overvoltages.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the voltage blocking capability of the transistor device is increased to withstand voltage spikes, then the reliability of the transistor device is improved, but the manufacturing cost increases

Engineering Contradiction:

Improvevoltage blocking capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The protection function is segmented from the main transistor device by introducing a separate clamping circuit with a second transistor device. This secondary device specifically handles voltage spike protection, allowing the first transistor device to be optimized for low conduction losses without needing excessive voltage blocking capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The clamping circuit uses a second transistor device that can be designed with lower voltage blocking requirements since it only needs to handle transient voltage spikes. This allows using more cost-effective transistor designs for the protection function rather than requiring the main device to be over-engineered for worst-case scenarios.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Productivity

If the transistor device switches faster from on-state to off-state, then the productivity is improved, but the voltage spikes increase

Engineering Contradiction:

Improveswitching speedVSAvoidvoltage spikes

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The clamping circuit converts the harmful voltage spikes generated by fast switching into a controlled protective mechanism. By detecting the voltage increase and activating the second transistor device, the circuit uses the spike itself as the trigger for protection, turning the adverse effect into the activation signal for the safety mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The clamping circuit acts as an intermediary protective layer between the voltage spikes and the first transistor device. When voltage spikes occur during switching transitions, the clamping circuit activates to limit the voltage, preventing direct exposure of the main transistor device to damaging overvoltages.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12431886B2Electronic circuit with a transistor device and a clamp circuit and method

Publication Date: 2025.09.30 INFINEON TECH AUSTRIA AG

AI summary

An electronic circuit and a method are disclosed. The electronic circuit includes: a first transistor device having a load path between a first load path node and a second load path node; and a clamping circuit connected to the load path of the first transistor device. The clamping circuit includes: a second transistor device having a load path connected in parallel with the load path of the first transistor device, and a control node; and a drive circuit configured to drive the second transistor device. The drive circuit includes a clamping element and a resistor connected in series between the first and second load path nodes of the first transistor device. The drive circuit is configured to drive the second transistor device dependent on a voltage across the resistor. The first transistor device and the clamping circuit are integrated in a same semiconductor die.