HV PMOS Driver With Constant Gate-Source Control at High Switching Speed
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Solution Overview
Problem
High-voltage CMOS devices face challenges in achieving accurate control voltage and minimizing static power dissipation while maintaining high switching speed, particularly in applications requiring supply voltages up to 40 Volts.
Innovation Solution
A driver circuit is designed with a high voltage power transistor, a resistive load, and a control stage using differential amplifiers to maintain a constant gate-source voltage, employing current mirroring to stabilize the voltage and reduce power dissipation, and additional smaller transistors for enhanced switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high voltage CMOS devices are used with extended drain region to reach up to 40V drain-source breakdown capability, then the voltage handling capability is improved, but the gate-source voltage is limited to 5V which restricts control accuracy and switching performance
Solution Approach 1:
A level translator circuit is introduced as an intermediary between the 5V logic control signal and the high voltage power transistor gate. This circuit uses a voltage divider network with resistors R1 and R2 to scale the 5V control signal to the appropriate gate-source voltage level for the high voltage transistor, enabling accurate control while maintaining the high voltage capability.
Solution Approach 2:
The invention changes the voltage level parameter from 5V logic level to a scaled high voltage level suitable for driving the power transistor gate. By using a voltage divider configuration, the gate-source voltage can be precisely controlled at the required level (e.g., 10V, 20V, or 40V) while the control input remains at standard 5V logic levels.
2Speed
If high voltage power transistors are driven with higher gate-source voltage to improve switching speed, then the switching performance is improved, but the static power dissipation increases
Solution Approach 1:
The gate drive circuit is designed to dynamically adjust the gate-source voltage based on the switching state. During switching transitions, higher voltage is applied to achieve fast switching. During the off-state, the gate voltage is pulled down to minimize leakage current and static power dissipation. This is achieved through the level translator circuit that can rapidly switch between different voltage levels.
Solution Approach 2:
The circuit employs periodic switching action where the gate voltage is applied in controlled pulses during switching operations and then removed during steady states. This periodic application of voltage reduces the average power dissipation while maintaining high switching speeds when needed, as the high voltage is only present during the brief switching transitions.
3Device complexity
If the gate-source voltage is limited to 5V in high voltage CMOS devices, then the device structure is simplified, but the control voltage accuracy and switching speed are compromised
Solution Approach 1:
The control system is segmented into two independent parts: a simple 5V logic control input stage and a high voltage output stage. The level translator circuit acts as the interface between these segments, allowing each part to be optimized independently - the logic stage for simplicity and the power stage for high voltage control accuracy - while maintaining overall system performance.
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
The solution provides accurate control voltage and minimizes static power dissipation, enabling faster switching speeds and reduced power loss across high voltage power transistors, even at varying temperatures and process conditions.
Implementation Method 1
a control stage to achieve a constant gate-source voltage of the high voltage power transistor
Implementation Method 2
control stage using differential amplifiers to maintain a constant gate-source voltage
Implementation Method 3
employing current mirroring to stabilize the voltage and reduce power dissipation
Data Source
AI summary
Systems and methods for providing a rapid switchable high voltage power transistor driver with a constant gate-source control voltage have been disclosed. A low voltage control stage keeps the gate-source voltage constant in spite of temperature and process variations. A high voltage supply voltage can vary between about 5.5 Volts and about 40 Volts. The circuit allows a high switching frequency of e.g. 1 MHz and minimizes static power dissipation.