Timing Controller for High Voltage Semiconductor Edge Delay
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Solution Overview
Problem
High voltage semiconductor devices are limited by the poor figure of merit of high breakdown voltage transistors, which restricts the operating frequencies and efficiency of control circuits, particularly in applications like power management and audio amplifiers, due to their high ON resistance and gate charge, making it difficult to charge and discharge quickly.
Innovation Solution
A timing control circuit using configurable edge delay circuits in series connection to control the timing of input square wave signals, allowing for independent delay of rising and falling edges based on the ON or OFF state of an input switch, and utilizing low breakdown voltage transistors to drive high voltage devices through a parallel resistive-capacitive coupling for efficient edge and DC level information transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high breakdown voltage transistors are used to control high voltage semiconductor devices, then the high voltage devices can be controlled, but the figure of merit is poor and operating frequencies are limited
Solution Approach 1:
The patent introduces an intermediary circuit stage between the low voltage control signal and the high voltage device gate. This intermediary stage uses low breakdown voltage transistors to generate control signals that are then coupled to the high voltage device through a resistive-capacitive network, allowing indirect control that avoids the limitations of direct high voltage transistor control
Solution Approach 2:
The patent replaces the mechanical/electrical direct control approach using high voltage transistors with an electrical field-based coupling approach. The resistive-capacitive coupling network transfers edge and DC level information through electrical fields, enabling control without direct electrical connection to high voltage nodes
2Reliability
If high breakdown voltage transistors are used in control circuits, then high voltage control is achieved, but the transistors have high ON resistance and gate charge making them difficult to charge and discharge quickly
Solution Approach 1:
The patent segments the control function into two separate stages: a first stage using low breakdown voltage transistors to generate control signals with fast switching speeds, and a second stage using resistive-capacitive coupling to transfer these signals to the high voltage device gate. This segmentation allows each stage to be optimized for its specific function
Solution Approach 2:
The patent uses low breakdown voltage transistors that can be quickly charged and discharged as temporary control signal generators. These transistors are not directly connected to high voltage nodes and can be rapidly switched without the need for high breakdown voltage ratings, effectively using simpler, faster components for the control signal generation function
3Productivity
If low breakdown voltage transistors are used to drive high voltage devices, then performance and cost are improved, but timing control of edges must be precise to avoid shoot-through currents
Solution Approach 1:
The patent implements preliminary dead time control by adding delay circuits to the control signal path before the signals reach the high voltage device gates. These delay circuits are configured to ensure that one device is fully turned off before the other device is turned on, preventing shoot-through currents while maintaining the benefits of using low breakdown voltage transistors
Solution Approach 2:
The resistive-capacitive coupling network provides feedback path that ensures proper timing synchronization between complementary control signals. The RC time constants are designed to provide appropriate delay and shaping, ensuring that edge timing is precisely controlled to prevent overlap of complementary signals
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
Enables robust and efficient control of high voltage devices using low breakdown voltage transistors, improving performance and cost by allowing regeneration of timing control signals even in cases of missed edges, and maintaining proper functionality without shoot-through currents.
Implementation Method 1
the edge delay is based on a charging time of one capacitor by a current source to reach a trip point voltage of an inverter
Implementation Method 2
utilizing low breakdown voltage transistors to drive high voltage devices through a parallel resistive-capacitive coupling for efficient edge and DC level information transmission
Implementation Method 3
utilizing low breakdown voltage transistors to drive high voltage devices through a parallel resistive-capacitive coupling for efficient edge and DC level information transmission
Data Source
AI summary
Systems, methods, and apparatus for use in biasing and driving high voltage semiconductor devices using only low voltage transistors are described. The apparatus and method are adapted to control multiple high voltage semiconductor devices to enable high voltage power control, such as power amplifiers, power management and conversion (e.g. DC/DC) and other applications wherein a first voltage is large compared to the maximum voltage handling of the low voltage control transistors. According to an aspect, timing control of edges of a control signal to the high voltage semiconductor devices is provided by a basic edge delay circuit that includes a transistor, a current source and a capacitor. An inverter can be selectively coupled, via a switch, to an input and/or an output of the basic edge delay circuit to allow for timing control of a rising edge or a falling edge of the control signal.