Temperature-Compensated LDO Circuit for Stable Ultra-Low Power Output
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Solution Overview
Problem
Existing low dropout regulators (LDOs) have complex structures and high power consumption, making them unsuitable for applications requiring low power consumption.
Innovation Solution
The LDO design includes a reference voltage generating circuit and a source follower, where the reference voltage changes with temperature to offset voltage changes, omitting the operational amplifier and resistor divider feedback network, resulting in a simpler circuit with ultra-low power consumption and stable output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional LDO structure with operational amplifier and resistor divider feedback network is used, then output voltage stabilization is achieved, but circuit complexity and power consumption increase
Solution Approach 1:
The patent extracts and removes the operational amplifier and resistor divider feedback network from the traditional LDO structure, retaining only the essential components (transistor, reference voltage source, and emitter resistor) needed for voltage regulation. This simplification reduces circuit complexity while maintaining core functionality through the transistor's inherent voltage regulation characteristics.
Solution Approach 2:
The patent utilizes the transistor's own characteristics (base-emitter voltage temperature dependence) to achieve temperature compensation and output voltage stabilization without requiring external feedback circuits. The emitter resistor leverages the transistor's natural behavior to self-regulate the output voltage, eliminating the need for additional active components.
2Reliability
If traditional LDO structure with operational amplifier and feedback network is used, then output voltage stabilization is achieved, but power consumption increases
Solution Approach 1:
The patent removes the power-hungry operational amplifier and feedback network from the circuit, reducing static power consumption significantly. The simplified structure relies on the transistor's natural voltage regulation and the temperature-compensating characteristics of the reference voltage source and emitter resistor, eliminating continuous power consumption associated with active feedback control.
Solution Approach 2:
The circuit uses the transistor's inherent voltage regulation capability and the temperature-dependent characteristics of the reference voltage source to automatically stabilize output voltage without requiring additional power for active control circuits. The emitter resistor provides automatic temperature compensation using the transistor's own operating characteristics.
3Reliability
If reference voltage changes with temperature is implemented, then temperature drift compensation is achieved, but circuit design complexity increases
Solution Approach 1:
The patent deliberately designs the reference voltage source to have a controlled temperature coefficient that changes with temperature. By selecting components with specific temperature characteristics (such as a bandgap reference or a voltage source with positive temperature coefficient), the circuit achieves automatic temperature drift compensation. The emitter resistor's temperature-dependent voltage drop counteracts the transistor's Vbe temperature variation, stabilizing the output voltage across temperature ranges.
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
This design achieves a stable output voltage that does not change with temperature, enabling the LDO to be applied in low power consumption scenarios, while simplifying the circuit structure and reducing power usage.
Implementation Method 1
the reference voltage generating circuit is configured to generate a reference voltage that changes with temperature, to offset a voltage change caused by a voltage between the first terminal and the second terminal of the source follower changing with temperature
Data Source
AI summary
Provided are an LDO, an MCU, a fingerprint module and a terminal device. The LDO includes: a reference voltage generating circuit and a source follower connected to the reference voltage generating circuit. The reference voltage generating circuit is used to generate a reference voltage that changes with temperature to offset a voltage change caused by a voltage between a first terminal and a second terminal of the source follower changing with time, so that an output voltage of the second terminal of the source follower does not change with temperature. The LDO omits an operational amplifier EA and a resistor divider feedback network in the prior art, which not only has a simple circuit structure, but also can achieve ultra-low power consumption.