Switching Regulator Current Detection With Low-Side Level Shifting
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Solution Overview
Problem
Existing semiconductor circuit devices for switching regulators face challenges in maintaining the characteristics of the differential amplifier circuit, particularly when the load is low or the power supply is turned on, leading to a decrease in output voltage and potential degradation of circuit performance.
Innovation Solution
The semiconductor circuit device includes a current detecting circuit, a differential amplifier circuit with a MOS transistor between a power supply node and an output node, a level shifter that shifts the output voltage to a low potential side, and a comparing circuit that generates a switching signal based on the current detection voltage and the level-shifted voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a level shifter level-shifts the output voltage of the differential amplifier to a higher voltage, then the voltage matching for subsequent stages is improved, but the output voltage of the differential amplifier decreases and its characteristics may degrade
Solution Approach 1:
The patent changes the voltage level parameter by introducing a level shifter that converts the differential amplifier's output voltage from a high level to a low level, enabling proper voltage matching for subsequent circuit stages while preserving the differential amplifier's operating characteristics
Solution Approach 2:
The level shifter acts as an intermediary component between the differential amplifier and the comparator, transforming the voltage level to enable proper signal transmission without directly modifying the differential amplifier's internal operation or output capability
2Device complexity
If the output voltage of the differential amplifier circuit is low, then the circuit structure is simplified, but the characteristics of the differential amplifier circuit degrade and switching regulator performance is compromised
Solution Approach 1:
The patent utilizes parameter changes in the transistor operating regions, allowing the differential amplifier to operate with low output voltage while maintaining proper transistor saturation through adjusted biasing and level shifting, thereby preserving circuit characteristics without increasing structural complexity
Data Source
AI summary
A semiconductor circuit device includes a current detecting circuit that converts an inductor current into a voltage and outputs the voltage as a current detection voltage, a differential amplifier circuit that amplifies a difference between a voltage corresponding to the output voltage and a reference voltage, a level shifter, and a comparing circuit that compares the current detection voltage with a level-shifted voltage and outputs a switching signal for a switching device. The differential amplifier circuit includes a MOS transistor provided between a power supply node and an output node. The level shifter level-shifts a voltage at the output node of the differential amplifier circuit to a low potential side and outputs the level-shifted voltage.