High-Voltage Amplifier Circuit With Precharged Isolated Drive
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Solution Overview
Problem
Existing high voltage amplifier circuits face challenges in achieving high response speed when varying the voltage value of the output signal, due to the weak output current from photocouplers leading to slow electrical charge storage in transistor input capacitance.
Innovation Solution
The high voltage amplifier circuit incorporates a constant current circuit with a light-emitting device, a light-responsive electricity generating device, and a transistor to continuously supply a constant current signal, allowing for quicker charge storage and enhanced responsiveness to voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photocoupler is used to drive the push-side field-effect transistor, then electrical isolation is achieved, but the response speed is slow due to weak output current
Solution Approach 1:
The patent divides the driving function into two separate circuits: a constant current circuit that continuously charges the input capacitance, and a push-pull circuit that performs the actual voltage amplification. This segmentation allows the photocoupler to operate in a stable constant current mode while the push-pull circuit provides the necessary current drive capability, resolving the contradiction between electrical isolation and response speed.
Solution Approach 2:
The constant current circuit performs preliminary action by continuously charging the input capacitance of the push-side field-effect transistor before a voltage variation request occurs. This pre-charging ensures that when voltage changes are needed, the transistor is already in a state ready for rapid response, eliminating the delay caused by slow photocoupler current charging.
2Reliability
If a high voltage resistance floating power supply is used, then the circuit can operate at high voltage, but the circuit size increases and noise is introduced
Solution Approach 1:
The patent extracts and eliminates the high voltage resistance floating power supply from the circuit by redesigning the constant current circuit to operate without it. The constant current circuit uses a light-emitting device and light responsive electricity generating device with ground potential supply, removing the source of coupling noise and reducing circuit complexity while maintaining high voltage operation capability through the push-pull circuit architecture.
Solution Approach 2:
The patent converts the potential harm of needing a complex floating power supply into a benefit by using a simpler ground-referenced constant current circuit. The light-emitting device and photodetector provide the necessary isolation and current control without requiring high voltage floating supplies, turning a potential complexity issue into a simplified design advantage.
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 design enables faster response times to requests for voltage variations, reduces circuit size by eliminating the need for a high voltage resistance floating power supply, and minimizes noise introduction, thereby improving overall performance and efficiency.
Implementation Method 1
a light-emitting device having one end supplied with the constant voltage signal and another end supplied with ground potential
Implementation Method 2
a light responsive electricity generating device for outputting a drive signal in response to light emitted by the light-emitting device
Data Source
AI summary
An amplifier circuit includes a constant current circuit for outputting a constant current signal at its output terminal, an operational amplifier for outputting an amplified control signal based on the first voltage signal, and an amplified voltage output circuit for outputting a second voltage signal based on both the constant current signal and the amplified control signal. The constant current circuit has a light-emitting device having one end supplied with the constant voltage signal and another end supplied with ground potential, a light responsive electricity generating device for outputting a drive signal in response to light emitted by the light-emitting device, a first transistor generating the constant current signal based on the amplified voltage signal applied thereto and to output the constant current signal; and a current control circuit for detecting the value of the constant current signal and controlling the supply of the drive signal based on the detection.