GaN Substrate Clamp Bias Circuits for Stable Switch Voltage

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Solution Overview

Problem

The electrical performance of semiconductor-based circuits is affected by unpredictable voltage changes on the semiconductor substrate, leading to undesirable performance variations.

Innovation Solution

A clamping circuit is implemented on a GaN substrate with a bidirectional switch, utilizing mirrored diode and switch circuits to control positive and negative voltage excursions, stabilizing the substrate voltage during transient events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a clamping circuit is implemented to stabilize substrate voltage, then voltage stability and circuit reliability are improved, but device complexity increases due to additional bias generator circuits and transistors

Engineering Contradiction:

Improvecircuit reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The clamping circuit is segmented into two separate bias generator circuits - a first bias generator circuit for clamping positive voltage excursions and a second bias generator circuit for clamping negative voltage excursions. Each bias generator circuit independently controls one polarity of voltage variation, allowing the complex function of bidirectional voltage clamping to be divided into manageable, specialized sub-circuits that can be optimized separately

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bias generator circuits act as intermediary components between the bidirectional switch and the substrate. These intermediary circuits generate compensating bias voltages that are applied to the substrate to counteract voltage excursions caused by the bidirectional switch, thereby isolating the substrate from direct voltage fluctuations while maintaining overall system functionality

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If bias generator circuits are used to control substrate voltage, then voltage excursion control is improved, but manufacturing complexity increases due to additional circuit components

Engineering Contradiction:

Improvevoltage control precisionVSAvoidease of manufacture

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The bias generator circuits dynamically adjust the substrate voltage parameter in response to detected voltage excursions. By changing the substrate voltage parameter in real-time based on the operating conditions and the polarity of voltage variations, the system achieves precise voltage control while adapting to different manufacturing tolerances and operational scenarios

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250216883A1Circuits and methods for generating bias voltages in substrate clamp circuits

Publication Date: 2025.07.03 NAVITAS SEMICON LTD

AI summary

An electronic device includes a gallium nitride (GaN) substrate having a GaN-based top layer attached to a silicon-based bottom layer, a bidirectional switch formed on the GaN-based top layer and including a first source node, a second source node and a common drain node, a first bias generator circuit arranged to couple the first source node to the silicon-based bottom layer, and a second bias generator circuit arranged to couple the second source node to the silicon-based bottom layer. In one aspect, when a voltage of the first source node is at a higher voltage than the second source node, the first bias generator circuit brings a voltage at the silicon-based bottom layer close to the voltage at the second source node.