Variable Feedback Divider in Voltage Regulators to Suppress Overshoot
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Solution Overview
Problem
Voltage regulators in semiconductor integrated circuits experience overshoot when external power-supply voltage fluctuates, leading to circuit instability and increased circuit scale due to the need for additional components like zener diodes or operational amplifiers.
Innovation Solution
A voltage regulator with a feedback loop circuit and a voltage-dividing ratio changing circuit that adjusts the feedback voltage using a voltage-controlled current source to maintain the feedback loop during power-supply voltage fluctuations, preventing overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a zener diode or voltage detection circuit is used to prevent overshoot, then overshoot is suppressed, but circuit area increases
Solution Approach 1:
The patent changes the resistance values of the voltage dividing resistors dynamically based on the input voltage level. When input voltage is low, the dividing ratio is adjusted to prevent the feedback voltage from exceeding the reference voltage, thereby suppressing overshoot without requiring additional components like zener diodes or operational amplifiers.
Solution Approach 2:
The voltage dividing ratio is made variable rather than fixed. The patent uses switching circuits to change the resistance configuration of the voltage dividing section according to input voltage conditions, enabling dynamic adaptation that prevents overshoot while maintaining a compact circuit structure.
2Device complexity
If a fixed voltage dividing ratio is used, then circuit is simple, but feedback voltage exceeds reference voltage when input voltage fluctuates causing overshoot
Solution Approach 1:
The voltage dividing ratio is made variable rather than fixed. The patent uses switching circuits to change the resistance configuration of the voltage dividing section according to input voltage conditions, enabling dynamic adaptation that prevents overshoot while maintaining a compact circuit structure.
Solution Approach 2:
The voltage dividing circuit automatically adjusts its own configuration based on input voltage levels without requiring external control circuits. The switching is performed internally within the voltage dividing section itself, eliminating the need for separate control mechanisms and maintaining circuit simplicity.
3Reliability
If voltage dividing ratio is changed to prevent overshoot, then voltage stability is improved, but circuit complexity increases
Solution Approach 1:
The overshoot prevention function is merged into the existing voltage dividing circuit rather than being implemented as a separate control circuit. The switching elements are integrated within the voltage dividing section, combining the voltage division and overshoot suppression functions in a single circuit block.
Solution Approach 2:
The resistance values of the voltage dividing resistors are changed dynamically based on input voltage conditions. By adjusting the resistance parameters within the existing circuit structure, the patent achieves overshoot suppression without adding complex control mechanisms.
Data Source
AI summary
A voltage regulator outputs a target voltage corresponding to a reference voltage Vref from a power-supply voltage Vin. The voltage regulator includes a feedback loop circuit, in which the reference voltage Vref is input, a feedback voltage after an output voltage Vout is divided is fed back, and the output voltage is controlled in correspondence with the reference voltage; and a voltage-dividing ratio changing circuit, which changes the feedback voltage by changing a voltage-dividing ratio of the output voltage Vout. When the power-supply voltage Vin drops and the target voltage cannot be maintained, the feedback voltage is increased according to the power-supply voltage by the voltage-dividing ratio changing circuit, thereby reducing the target voltage.