LDO Regulator Leakage Compensation via Thermal Coupling
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Solution Overview
Problem
Low-dropout (LDO) regulators face challenges in efficiently compensating for leakage current at high temperatures without increasing power consumption or complex control, especially in ultra-low-power designs, as existing solutions either consume additional current or require complex circuitry.
Innovation Solution
A method involving a non-proportional-to-temperature (non-PTAT) type sink current generator thermally coupled with the LDO regulator on the same semiconductor substrate, providing a sink current that matches the temperature characteristic of the output transistor leakage current, allowing for optimized quiescent current consumption and scalable leakage current compensation across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage monitor and clamping circuitry is used to compensate leakage current, then leakage current compensation is achieved, but additional current consumption increases
Solution Approach 1:
The output transistor's own leakage current is utilized to compensate for leakage current through a feedback mechanism. The leakage current flowing through the output transistor is sensed and fed back to the error amplifier, which automatically adjusts the drive signal to compensate for the leakage, eliminating the need for external monitoring circuitry and reducing additional current consumption.
2Adaptability or versatility
If a LDO regulator with source-sink output stage is used, then sink capability is improved, but device complexity and current consumption increase
Solution Approach 1:
The output stage dynamically adapts its characteristics based on operating conditions. By utilizing the inherent leakage current of the source output transistor and feeding it back to the error amplifier, the circuit automatically adjusts to provide effective sink capability without requiring a separate sink transistor or complex dual-output-stage circuitry, thereby maintaining simplicity while achieving adaptability.
3Reliability
If a constant-current sink with fixed value is used, then maximum leakage current compensation is achieved, but quiescent current consumption increases
Solution Approach 1:
Instead of using a fixed constant-current sink, the compensation mechanism dynamically adjusts the compensation current based on the actual leakage current of the output transistor. The error amplifier modulates the drive signal to the output transistor based on feedback from its leakage current, ensuring optimal compensation at all temperatures while minimizing quiescent current consumption, as the compensation current varies with temperature and load conditions rather than remaining fixed.
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 approach enables a low quiescent current LDO regulator with high output drive capability at high temperatures, minimizing power consumption and avoiding the need for additional monitoring or complex control, while maintaining stable operation and reducing current consumption.
Implementation Method 1
A method involving a non-proportional-to-temperature (non-PTAT) type sink current generator thermally coupled with the LDO regulator on the same semiconductor substrate
Data Source
AI summary
Circuits and methods to compensate leakage current of a LDO regulator are disclosed. The compensation is achieved by a temperature dependent sink current generation, matched with its temperature dependency characteristic to the LDO regulator output transistor leakage, which has a nearly zero current consumption increase of about 50 nA at room temperature and starts sink current at temperatures about above 85 to 125 degrees Celsius, which is corresponding to a range of temperature wherein leakage currents come into account.