Digital LDO Current Measurement Using DAC Code Feedback
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Solution Overview
Problem
Existing current measurement systems for digital low dropout regulators (LDOs) lack an efficient method to accurately measure the output current, which is crucial for maintaining stability and efficiency in voltage regulation.
Innovation Solution
A current measurement system for digital LDOs that includes a current determination unit configured to receive the DAC code signal and generate an output current signal, utilizing a current mirror scheme for precise current control and an average current determination unit with an IIR filter for smoothing the output current measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current measurement system is added to the digital LDO, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent creates a digital copy of the output current information by capturing the DAC code that controls the current sources. Instead of measuring the actual current flow, the system copies the control signal (DAC code) and uses it to determine the output current, thereby avoiding complex physical measurement circuits while achieving precise measurement.
Solution Approach 2:
The patent introduces an intermediary approach by using the DAC code as a proxy for direct current measurement. The DAC code serves as an intermediate representation that contains all necessary information about the output current without requiring direct electrical measurement, thus simplifying the overall system architecture.
2Stability of the object's composition
If real-time current feedback is implemented, then stability is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback by monitoring the DAC code and using it to determine output current information. This feedback mechanism allows the system to maintain stability by having real-time knowledge of the output current state without requiring complex additional feedback circuits, as the feedback is derived from existing control signals.
Solution Approach 2:
The system uses its own internal DAC code signals to provide current measurement and feedback functionality. Rather than requiring external measurement circuits, the digital LDO leverages its existing control architecture to generate the measurement information, making the system self-sufficient and reducing overall complexity.
3Reliability
If limit cycling is reduced through precise measurement, then voltage regulation performance is improved, but measurement precision requirements increase device complexity
Solution Approach 1:
The patent achieves precise measurement by copying the DAC code, which inherently contains precise information about the intended current output. This copying approach provides high measurement precision without requiring complex measurement hardware, as the precision is derived from the digital control signal itself rather than analog measurement circuits.
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
The proposed system enables accurate measurement of output current, improving the stability and efficiency of digital LDOs by providing real-time feedback and reducing limit cycling, thus enhancing overall voltage regulation performance.
Implementation Method 1
The current mirror scheme 138 comprises transistors 140, current sources 142, a capacitor 144, an amplifier 146 and a sink buffer 148
Implementation Method 2
an average current determination unit with an IIR filter for smoothing the output current measurement
Data Source
AI summary
A current measurement system for a digital low dropout regulator (LDO) for receiving a reference voltage and generating an output voltage, the output voltage of the digital LDO being dependent on a first DAC code signal, the current measurement system comprising a current determination unit configured to receive the first DAC code signal, and generate an output current signal using the first DAC code signal.