LDO Regulator Sensing Circuit for Fast Droop Response and Stability
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Solution Overview
Problem
Designing a low-dropout (LDO) voltage regulator that can support a wide range of output capacitance and load current while maintaining performance and stability is challenging, especially in systems with high frequency voltage droops and unpredictable load currents.
Innovation Solution
The LDO voltage regulator incorporates an open-loop control circuit with adaptive zero mechanism, which allows for rapid response to high frequency voltage droops and accurate measurement of load current profiles. This design includes voltage sensing and calibration operations to enhance the performance of the open-loop control circuit and measurement circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional LDO voltage regulator design is used, then the device can cover a wide range of output capacitance, but it cannot achieve fast response time to high frequency voltage droops
Solution Approach 1:
The patent divides the voltage regulation function into two independent branches: a closed-loop feedback branch for DC voltage regulation and an open-loop branch for AC voltage droop suppression. This segmentation allows each branch to be optimized independently - the open-loop branch provides fast response to high frequency droops while the closed-loop branch maintains stability across wide capacitance ranges.
Solution Approach 2:
The patent implements dynamic control by using a capacitor that can be selectively connected or disconnected based on operating conditions. The capacitor is connected during transient states to provide fast response and disconnected during steady-state to maintain stability, enabling the system to adapt its characteristics dynamically rather than being fixed.
2Speed
If an open-loop branch is added to improve response time, then fast response to high frequency voltage droops is achieved, but mismatch between predicted and actual load current degrades performance
Solution Approach 1:
The patent combines open-loop and closed-loop control architectures where the closed-loop feedback continuously monitors the output voltage and corrects DC errors, while the open-loop branch handles fast AC transient response. This dual-loop approach ensures that even when open-loop predictions mismatch actual load conditions, the feedback loop compensates to maintain overall system reliability and accuracy.
3Measurement precision
If current measurement is included in LDO voltage regulator design, then load current profile measurement capability is provided, but measurement accuracy cannot be achieved at acceptable cost
Solution Approach 1:
The patent introduces a dedicated current measurement circuit that acts as an intermediary between the power management system and the control logic. This separate measurement circuit provides accurate load current profile data without complicating the core LDO regulation circuitry, allowing precise measurements while maintaining acceptable overall design complexity.
Data Source
AI summary
Some embodiments include an apparatus having a low-dropout (LDO) voltage node; a driver including an output node coupled to the LDO voltage node to provide a current at the LDO voltage node; a comparator including an input node coupled to the output node of the driver and an output node coupled to an input node of the driver; a current generator coupled to the driver to generate a second current based on the first current; and a frequency compensation network coupled to the comparator and the current generator.