Dynamic Biasing Circuit for LDO Regulator Transient Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional low drop out (LDO) regulators face challenges in managing quiescent current during standby mode and providing good transient response during active mode, often resulting in output oscillations and power-on-resets due to abrupt bias current changes, which can lead to unexpected IC states and reduced area efficiency.
Innovation Solution
A dynamic biasing circuit that monitors and selects between a standby current and an active current, using a current selector circuit with multiple current mirrors to provide a gradual and high-speed transition of the bias current, ensuring low quiescent current in standby mode and superior transient response in active mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the LDO regulator uses a fixed bias current design, then it can provide good transient response during active mode, but it results in high quiescent current during standby mode
Solution Approach 1:
The patent implements dynamic biasing by switching between a first bias current (for standby mode) and a second bias current (for active mode) based on the operational state of the digital core. This dynamic adjustment allows the LDO regulator to optimize its performance for each mode: using lower bias current during standby to reduce quiescent current consumption, and higher bias current during active mode to ensure good transient response when load current changes abruptly.
2Speed
If the LDO regulator abruptly changes bias current during mode transitions, then it can quickly adapt to load changes, but it causes output oscillations and power-on-resets
Solution Approach 1:
The patent employs a gradual transition mechanism where the bias current is switched from the first bias current to the second bias current (or vice versa) in a controlled manner rather than abruptly. This preliminary action prevents sudden current changes that would cause output voltage oscillations and power-on-resets, ensuring stable operation during mode transitions while still maintaining fast adaptation to load changes.
3Reliability
If the LDO regulator uses dynamic biasing with multiple current mirrors, then it achieves low quiescent current and good transient response, but it increases circuit complexity
Solution Approach 1:
The patent divides the biasing circuit into multiple current mirrors (first current mirror, second current mirror, third current mirror, and fourth current mirror), each responsible for generating or switching specific bias currents. This segmentation allows independent optimization of each current path and simplifies the control logic for switching between standby and active modes, making the overall complex function manageable through modular design.
Solution Approach 2:
The current mirrors in the patent serve multiple functions: they generate bias currents, switch between different bias current levels, and provide current scaling. By making these components multi-functional, the patent reduces the need for separate dedicated circuits for each function, thereby managing complexity while achieving the desired performance in both standby and active modes.
Data Source
AI summary
Dynamic biasing circuits for low drop out (LDO) regulators are described. In some embodiments, an electronic circuit may include a low drop out (LDO) regulator; and a biasing circuit coupled to the LDO regulator, the biasing circuit configured to: monitor a first electrical current and a second electrical current; select a greater of the first or second electrical currents; and provide the selected electrical current to the LDO regulator. In other embodiments, a method may include: providing a digital core and a low drop out (LDO) regulator coupled to the digital core, wherein the digital core is configured to operate in an active mode and in a standby mode; monitoring, via a current selector circuit coupled to the LDO regulator, a first current and a second current; selecting a greater of the first or second electrical currents; and providing the selected current as a biasing current to the LDO regulator.