Power Control Semiconductor Device Linear Voltage Adjustment
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Solution Overview
Problem
Conventional power control semiconductor devices face challenges in miniaturization and precision due to the need for increased components and resistance variations, leading to non-linear output voltage changes and potential malfunctions.
Innovation Solution
A power control semiconductor device configuration with a control circuit that includes a first divider, error amplifiers, and resistor elements formed as diffusion layers on a semiconductor substrate, where the output voltage change circuit uses a second error amplifier and transistors to adjust the output voltage linearly, reducing bias dependence and preventing malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of series resistors and switch transistors is increased to change output voltage approximately linearly, then the linearity of output voltage change is improved, but the number of elements is increased so that the elements occupy a larger area
Solution Approach 1:
The patent changes the parameter of resistance value continuously by using a diffusion resistor with variable resistance characteristics. The diffusion resistor is designed to have a resistance value that changes in proportion to the control signal, enabling linear output voltage change without increasing the number of discrete resistor elements. This resolves the contradiction by achieving linearity through parameter variation rather than through increasing component count.
2Manufacturing precision
If an external element is used to adjust output voltage value, then the output voltage can be changed linearly, but the number of components is large so that the components occupy a larger area
Solution Approach 1:
The patent merges the voltage adjustment function with the internal diffusion resistor structure. Instead of using separate external adjustment components, the diffusion resistor is designed to provide both the bias current path and the variable resistance characteristic needed for linear voltage adjustment. This integration reduces the number of components while maintaining linear output voltage change capability.
3Reliability
If diffusion resistors are used with different island potentials, then the circuit can operate with proper biasing, but the resistance values vary due to bias dependence so that precision of output voltage is lowered
Solution Approach 1:
The patent applies equipotentiality by setting the island potential of the diffusion resistor to be equal to the output voltage. This ensures that the voltage across the diffusion resistor remains constant regardless of changes in output voltage, eliminating the bias dependence effect. As a result, the resistance value of the diffusion resistor remains stable and precise, resolving the contradiction between proper biasing and voltage precision.
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 improves linearity of output voltage changes in response to control signals, reduces the number of components, and prevents malfunctions, allowing for miniaturization and stable operation without increasing power consumption.
Implementation Method 1
it has been found that a diffusion resistor formed on a semiconductor substrate has bias dependence that a resistance value changes in accordance with a change in thickness of a depletion layer
Implementation Method 2
the PN junction between the diffusion resistor and the island area is always reverse-biased. This is to prevent an undesired current from flowing into a parasitic element (PN junction)
Data Source
AI summary
A power control semiconductor device includes: a voltage control transistor connected between an input terminal and an output terminal; a control circuit that controls the voltage control transistor in accordance with a voltage of the output terminal; and an external terminal that controls an output voltage externally. The control circuit includes: a first divider which has resistor elements connected in series to the output terminal and which divides the output voltage of the output terminal; a first error amplifier that outputs a voltage corresponding to a potential difference between a predetermined reference voltage and a voltage divided by the first divider; and an output voltage change circuit that changes the divided voltage in accordance with a voltage input to the external terminal to change the output voltage in accordance with the voltage of the external terminal.