Segmented Gate Transistors with Distributed Resistors for Stability

Solution Overview

Problem

High power, high frequency transistors face challenges in maintaining high frequency performance and reliability due to increased current densities and electromigration issues associated with wider gate fingers, which can lead to instability and reduced gain.

Innovation Solution

The implementation of a transistor design with segmented gate fingers and distributed series gate resistors and odd mode resistors, where the gate signal is fed at multiple locations along the gate finger, and series gate resistors are positioned between gate splits to break up long feedback loops, reducing instability and current density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If gate fingers are made wider to increase output power, then power handling capability is improved, but high frequency performance deteriorates and electromigration occurs

Engineering Contradiction:

Improveoutput powerVSAvoidhigh frequency performance

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The gate finger is divided into multiple segments along its length, with each segment independently connected to the gate electrode. This segmentation reduces the effective gate width that carries full current while maintaining the physical gate periphery for power handling, thereby improving high frequency performance and reducing electromigration effects

Inventive Principle:

Principle #1Segmentation

2Power

If gate fingers are made wider to increase output power, then power handling capability is improved, but current density increases causing electromigration

Engineering Contradiction:

Improveoutput powerVSAvoidelectromigration

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The gate finger is divided into multiple segments along its length, with each segment independently connected to the gate electrode. This segmentation reduces the effective gate width that carries full current while maintaining the physical gate periphery for power handling, thereby improving high frequency performance and reducing electromigration effects

Inventive Principle:

Principle #1Segmentation

3Power

If gate fingers are made wider to increase output power, then power handling capability is improved, but stability deteriorates due to feedback loops

Engineering Contradiction:

Improveoutput powerVSAvoiddevice stability

Core Design Contradiction:

PowerVSStability of the object's composition

Solution Approach 1:

The gate finger is divided into multiple segments along its length, with each segment independently connected to the gate electrode. This segmentation reduces the effective gate width that carries full current while maintaining the physical gate periphery for power handling, thereby improving high frequency performance and reducing electromigration effects

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Resistors are introduced as intermediary elements between the gate electrode segments and the gate finger segments. These resistors act as lossy elements that dampen feedback loops and improve device stability while maintaining the segmented gate structure

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20230253490A1Bypassed gate transistors having improved stability

Publication Date: 2023.08.10 MACOM TECH SOLUTIONS HLDG INC

AI summary

A transistor device includes a plurality of gate fingers that extend in a first direction and are spaced apart from each other in a second direction, each of the gate fingers comprising at least spaced-apart and generally collinear first and second gate finger segments that are electrically connected to each other. The first gate finger segments are separated from the second gate finger segments in the first direction by a gap region that extends in the second direction. A resistor is disposed in the gap region.