Power Converter Startup Circuit Using Negative-Threshold Transistors
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Solution Overview
Problem
Traditional high voltage start up circuits for power converters suffer from significant power loss due to the use of high resistance resistors, which are not suitable for integration into circuits, necessitating a high efficiency solution for integrated circuits.
Innovation Solution
A start up circuit comprising a first transistor with negative-threshold voltage, a second transistor, a third transistor, and a diode, where the resistive device provides bias voltage to turn on the transistors, allowing for efficient power management and integration into an integrated circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a high resistance resistor is used to reduce power loss, then power consumption is reduced, but the resistor cannot be integrated into an integrated circuit
Solution Approach 1:
The patent changes the electrical parameters of the circuit by using a negative-threshold voltage transistor instead of a high resistance transistor. This parameter change allows the circuit to achieve low power consumption without requiring high resistance values that cannot be integrated. The negative threshold voltage characteristic enables the transistor to operate in a mode that minimizes power loss while maintaining integrability into standard IC processes.
Solution Approach 2:
The patent replaces the mechanical/discrete high resistance resistor with an electronic solution using a negative-threshold voltage transistor. This substitution allows the circuit to achieve the same power loss reduction function while being compatible with integrated circuit fabrication, as the transistor can be manufactured using standard IC processes rather than requiring external high resistance components.
2Use of energy by moving object
If a transistor is used to control the start up circuit, then power consumption is reduced after start up, but power loss occurs during the turning off process
Solution Approach 1:
The patent employs periodic action through the use of a negative-threshold voltage transistor that automatically transitions between on and off states based on the voltage conditions. During start-up, the transistor is on to provide current; after the control circuit voltage reaches a certain level, the transistor automatically turns off. This periodic operation reduces power consumption while minimizing switching losses through the unique negative threshold voltage characteristic.
Solution Approach 2:
The negative-threshold voltage transistor performs self-service by automatically turning off the start-up circuit when the control circuit voltage reaches the appropriate level. The transistor monitors its own operating conditions and transitions states without requiring external control signals, thereby reducing power consumption while eliminating the need for additional control circuitry that would increase power loss.
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 reduces power consumption and enables integration into an integrated circuit by using a resistive device to manage bias voltage effectively, minimizing power loss and enhancing efficiency.
Implementation Method 1
The first transistor has a negative-threshold voltage. The third transistor is connected in serial with the first transistor to output a voltage VD in response to the voltage source VIN to provide a supply voltage to the control circuit
Implementation Method 2
The diode is coupled from a transformer winding of the power converter to provide a further supply voltage to the control circuit of the power converter
Implementation Method 3
The resistive device provides a bias voltage to turn on the third transistor and the first transistor when the second transistor is turned off
Data Source
AI summary
A start up circuit of power converters is presented. It includes a first transistor, a resistive device, a second transistor, a third transistor and a diode. The first transistor is coupled to a voltage source. The third transistor is connected in serial with the first transistor to output a supply voltage to a control circuit of the power converter in response to the voltage source. The diode is connected from a transformer winding of the power converter to supply a further supply voltage to the control circuit of the power converter. The second transistor is coupled to control the first transistor and the third transistor in response to a control signal. The resistive device provides a bias voltage to turn on the first transistor and the third transistor when the second transistor is turned off. Once the second transistor is turned on, the third transistor is turned off and the first transistor is negative biased.