LDO Voltage Regulator Current Detection with Segmented Transistors
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Solution Overview
Problem
Conventional LDO voltage regulators face challenges in achieving accurate current detection due to varying current density and resistance in output transistors, especially when input voltage changes, leading to inconsistent pair properties and reduced detection accuracy.
Innovation Solution
The proposed LDO voltage regulator employs a configuration with multiple transistors and amplifying circuits to maintain equal voltages across different transistors, using a comparator and resistor circuit to adjust resistance states based on voltage differences, ensuring accurate current detection across a wider range of current values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the output transistor size is increased to pass high current, then the current carrying capacity is improved, but the pair properties between output transistor and detecting transistor cannot be ensured due to size mismatch
Solution Approach 1:
The patent divides the current detection function into multiple stages by introducing an intermediate detecting transistor that is size-matched with the output transistor, while a second detecting transistor handles the detection signal. This segmentation allows each transistor to operate within its optimal size range, ensuring accurate pair matching while maintaining high current capacity.
2Power
If the output transistor size is increased, then the current carrying capacity is improved, but the current density varies and resistance becomes variable
Solution Approach 1:
The patent introduces an intermediate detecting transistor as a mediator between the large output transistor and the detection circuitry. This intermediate transistor is sized to match the output transistor, ensuring consistent current density and resistance characteristics. The second detecting transistor then accurately detects the voltage across this intermediate transistor, enabling precise current measurement despite the large size of the output transistor.
3Device complexity
If conventional LDO voltage regulator configuration is used, then the structure is simple, but accurate current detection cannot be achieved when input voltage varies
Solution Approach 1:
The patent implements a dynamic current detection system that adapts to varying input voltages. By using multiple detecting transistors with different sizing relationships and multiple amplifying circuits that can be selectively activated, the system dynamically adjusts its detection mechanism based on operating conditions, maintaining high measurement precision across different voltage scenarios.
Solution Approach 2:
The patent changes the detection parameters by switching between different detecting transistors and amplifying circuits based on the input voltage level. When input voltage is high, one set of detection parameters is used, while when input voltage is low, another set is activated. This parameter adaptation ensures accurate current detection across the full voltage range without requiring a single complex detection circuit.
Data Source
AI summary
The voltage regulator includes a resistor circuit that switches between a first state and a second state according to the comparison result signal. In the first state, a resistance between a second end of a first controlling transistor and a fixed potential is set at a first resistance, and a second end of a second controlling transistor and the fixed potential are disconnected from each other. In the second state, the second end of the first controlling transistor and the fixed potential are disconnected from each other, and a resistance between the second end of the second controlling transistor and the fixed potential is set at a second resistance.