Driver Efficiency via Serial Low Voltage Transistors

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Solution Overview

Problem

Conventional switching regulators used in drivers for AMOLED panels face inefficiency due to high voltage transistors, which result in significant switching losses and reduced efficiency, especially under varying load conditions.

Innovation Solution

The use of serially connected low voltage transistors to replace high voltage transistors and the dynamic adjustment of high voltage transistor sizes through parallel sub-transistors to minimize parasitic capacitance and switching losses, thereby enhancing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If high voltage transistors are used to handle high voltage across the switching nodes, then the voltage conversion function is achieved, but the gate-source parasitic capacitance and gate-drain parasitic capacitance increase, resulting in significant switching loss and reduced efficiency

Engineering Contradiction:

Improvevoltage handling capabilityVSAvoidswitching loss

Core Design Contradiction:

Stress or pressureVSLoss of energy

Solution Approach 1:

The patent divides a single high voltage transistor into multiple low voltage transistors connected in series. Each low voltage transistor handles a portion of the total voltage, reducing the voltage stress on individual devices. This segmentation allows the use of low voltage transistors with smaller parasitic capacitances, thereby reducing switching losses while maintaining the required voltage handling capability of the overall circuit

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the voltage parameter specification from high voltage to low voltage by using multiple low voltage transistors in series. Each transistor operates within its low voltage rating, but the series combination achieves the required high voltage handling. This parameter change enables the use of transistors with optimized parasitic capacitance characteristics, improving switching efficiency

Inventive Principle:

Principle #35Parameter changes

2Power

If high voltage transistors are used to ensure voltage conversion capability, then the circuit can operate at required voltage levels, but the switching efficiency deteriorates especially under light loading conditions

Engineering Contradiction:

Improvevoltage conversion capabilityVSAvoidswitching efficiency

Core Design Contradiction:

PowerVSProductivity

Solution Approach 1:

The patent segments the high voltage transistor into multiple series-connected low voltage transistors, where each transistor handles a fraction of the total voltage. This segmentation reduces the parasitic capacitance of each individual transistor, leading to faster switching speeds and improved efficiency, particularly under light loading conditions where switching losses have a more significant impact on overall efficiency

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates a composite transistor structure by combining multiple low voltage transistors in series to function as a single high voltage transistor. This composite structure achieves both the required voltage handling capability and the improved switching characteristics of low voltage devices, optimizing both power capability and productivity

Inventive Principle:

Principle #40Composite materials

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 significantly improves the efficiency of the driver, with maximum efficiency increased by up to 90%, reducing switching losses and maintaining circuit area, while effectively handling varying load conditions.

Implementation Method 1

a high voltage transistor has larger parasitic capacitances between its gate and source and between its gate and drain

Methodology Applied

Scientific EffectParasitic capacitance: Capacitance

Implementation Method 2

Switching regulators have been widely applied in various power supplies and drivers, to convert an input voltage to a regulated output voltages by switching one or more power switches

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS8952670B2Efficiency improvement of a driver by using serially connected low voltage transistors or dynamic transistor size control

Publication Date: 2015.02.10 RICHTEK TECH

AI summary

Serially connected low voltage transistors are used to replace a high voltage transistor in a voltage conversion circuit for a driver, or parallel connected sub-transistors are used to establish a high voltage transistor having an effective size dynamically adjusted according to loading of the driver, to reduce switching loss and thereby improve the efficiency of the driver.