Variable Step-Up Circuit for Wide Supply Voltage Range
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Solution Overview
Problem
Existing step-up circuits have a limited supply voltage range due to voltage exceeding the semiconductor process withstand voltage when operating near it, leading to reliability issues and inadequate voltage increase at low supply voltages.
Innovation Solution
A step-up circuit with a capacitor and a reference voltage generator circuit that adjusts the voltage increase rate relative to the supply voltage, using transistors and inverters to control the charging of sampling capacitors, allowing for a wider usable supply voltage range by varying the reference voltage based on the supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a step-up circuit increases supply voltage to a fixed ratio (e.g., twofold), then the voltage increase is sufficient at low supply voltages, but the increased voltage exceeds the semiconductor process withstand voltage when operating near the maximum supply voltage
Solution Approach 1:
The patent applies dynamics by making the voltage increase ratio variable rather than fixed. The circuit dynamically adjusts the voltage multiplication factor based on the input supply voltage level, using control logic that modifies the charging/discharging cycles of capacitors to achieve different step-up ratios, thereby adapting to varying operating conditions
Solution Approach 2:
The patent changes the parameter of voltage increase ratio from a constant value to a variable parameter that depends on the supply voltage. By monitoring the supply voltage level and adjusting the step-up ratio accordingly, the circuit maintains the increased voltage within safe operational limits across the entire supply voltage range
2Device complexity
If a step-up circuit uses a fixed voltage increase ratio, then the circuit design is simple, but the circuit cannot maintain reliable operation across a wide supply voltage range
Solution Approach 1:
The patent implements feedback by monitoring the supply voltage level and using this information to control the voltage increase ratio. The control circuit receives feedback about the input voltage conditions and automatically adjusts the step-up operation to maintain output voltage within acceptable ranges, ensuring reliable operation without excessive complexity
Data Source
AI summary
A step-up circuit includes a capacitor, a transistor connected to the capacitor, and a reference voltage generator circuit configured to supply the transistor with a reference voltage that causes a rate of voltage increase relative to supply voltage to vary in accordance with the supply voltage.