Switching Regulator Low Start-Up Voltage Charge Pump
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Solution Overview
Problem
Existing switching regulators require low threshold voltage transistors for low start-up voltage, which increases manufacturing costs and leads to undesirable leakage current at normal input voltages.
Innovation Solution
A switching regulator design using a power stage with a low threshold voltage transistor as a power switch, where the threshold voltage is adjusted without additional manufacturing masks, and a switch control circuit that includes oscillators and charge pumps to generate control signals, reducing the need for low threshold voltage transistors and minimizing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If low threshold voltage transistors are used for low start-up voltage, then the start-up voltage is reduced, but the manufacturing cost increases and leakage current occurs at normal input voltages
Solution Approach 1:
The patent uses a charge pump circuit to dynamically change the threshold voltage parameter of the power switch transistor. During start-up, the threshold voltage is lowered to enable operation at low input voltages. During normal operation, the threshold voltage returns to its original value to prevent leakage current and eliminate the need for special low-threshold-voltage transistors, thus resolving the manufacturing cost issue while maintaining low start-up voltage capability
2Temperature
If low threshold voltage transistors are used for low start-up voltage, then the start-up voltage is reduced, but leakage current is generated at normal input voltages
Solution Approach 1:
The patent implements a dynamic threshold voltage adjustment mechanism where the power switch transistor's threshold voltage changes based on operating conditions. During start-up, the threshold voltage is dynamically lowered to enable low-voltage operation. During normal operation, the threshold voltage is dynamically restored to its original level, preventing leakage current. This dynamic adjustment resolves the contradiction between low start-up voltage and leakage current prevention
3Temperature
If low threshold voltage transistors are used, then low start-up voltage is achieved, but extra manufacturing steps and masks are required
Solution Approach 1:
The patent uses a standard-threshold-voltage transistor as a template and creates the low-threshold-voltage state temporarily through the charge pump circuit rather than manufacturing a completely different low-threshold-voltage transistor. This approach copies the functional behavior of low-threshold-voltage transistors during start-up without requiring the extra manufacturing steps and masks, thus resolving the device complexity issue while maintaining low start-up voltage capability
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 allows for a low start-up voltage without the need for extra manufacturing steps, reducing costs and minimizing leakage current, while maintaining efficient operation across varying input voltages.
Implementation Method 1
the first charge pump is configured to operably generate a second input voltage related signal according to the first clock signal, wherein a voltage level of the second input voltage related signal is higher than a voltage level of the first input voltage related signal
Data Source
AI summary
A switching regulator having a low start-up voltage includes a power stage and a switch control circuit. The switch control circuit includes a power control switch. The power control switch is formed by a low threshold voltage transistor having a first conductivity type in a semiconductor substrate. The low threshold voltage transistor having the first conductivity type includes a first lightly doped region having a second conductivity type which forms a channel region of the low threshold voltage transistor having the first conductivity type. The semiconductor substrate includes a second lightly doped region having the second conductivity type which is formed by a same manufacturing process as the first lightly doped region having the second conductivity type. The second lightly doped region having the second conductivity type forms adrift region of a high-voltage transistor having the second conductivity type in the semiconductor substrate.