Transistor Drain Center Tap and Capacitance Compensation

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Solution Overview

Problem

Existing transistor devices face inefficiencies due to parasitic effects, such as internal resistances causing voltage drops and power dissipation, which limit their ability to handle high currents and voltages effectively, especially as they operate at increasing speeds.

Innovation Solution

The introduction of a center tap on the drain with varying gate-to-drain capacitances, where current enters at a midpoint and flows symmetrically outward, compensating for different resistive paths by adjusting the width of the backend metal layer along the drain to maintain a balanced RC time constant across the transistor length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If transistors are operated at increasing speeds to meet performance demands, then processing speed and current delivery capability are improved, but parasitic effects such as internal resistance cause increased voltage drops and power dissipation

Engineering Contradiction:
Improvetransistor operating speedVSAvoidpower dissipation
Core Design Contradiction:
SpeedVSLoss of energy

Solution Approach 1:

The patent applies local quality by varying the gate-to-drain capacitance at different locations along the drain length. The capacitance is adjusted locally to compensate for position-dependent resistive effects, with different capacitance values applied to different segments of the drain to optimize performance at each location while managing overall power dissipation

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the capacitance parameter along the drain length to compensate for parasitic effects. By varying the gate-to-drain capacitance as a function of position, the patent optimizes the RC time constant distribution to maintain consistent delay characteristics across different operating conditions and reduce power loss

Inventive Principle:
Principle #35Parameter changes

2Power

If transistors are designed to deliver large amounts of current at very high speeds, then current delivery capability is improved, but internal resistance causes increased voltage drops that limit device size

Engineering Contradiction:
Improvecurrent delivery capabilityVSAvoiddevice size constraints
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent uses local quality by implementing position-dependent gate-to-drain capacitance along the drain. This allows different regions of the transistor to be optimized for their specific function, enabling high current delivery without requiring uniform design parameters that would constrain device size

Inventive Principle:
Principle #3Local quality

3Power

If transistors must manage high power levels and high voltages, then power management capability is improved, but parasitic effects increase and existing solutions are not optimal

Engineering Contradiction:
Improvepower management capabilityVSAvoidparasitic effects
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The patent changes the capacitance parameter along the drain length to compensate for parasitic effects that become more significant at high power levels. This parameter variation optimizes the RC time constant distribution, maintaining consistent delay characteristics and reducing the impact of parasitic resistance and capacitance in high-voltage applications

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces power loss and maintains a consistent delay across the transistor, enhancing its performance by balancing resistive paths and stabilizing the device, particularly in high-voltage applications.

Implementation Method 1

varying gate-to-drain capacitances, where current enters at a midpoint and flows symmetrically outward, compensating for different resistive paths by adjusting the width of the backend metal layer along the drain to maintain a balanced RC time constant across the transistor length

Methodology Applied
Scientific EffectRC time constant: Capacitance

Data Source

PatentEP3195362B1Transistor devices and methods
Publication Date: 2018.07.18 QUALCOMM INC
  • EP3195362B1 patent drawingFigure 1~2B
  • EP3195362B1 patent drawingFigure 3
  • EP3195362B1 patent drawingFigure 4~5

AI summary

The present disclosure includes transistor devices and methods. In one embodiment, a transistor includes a gate, a source, and a drain. According to one aspect of the disclosure, different resistive paths in the drain are compensated using different gate-to-drain capacitances. According to another aspect of the disclosure, current enters a drain at a center tap point and flows symmetrically outward under two adjacent gates to two adjacent sources.