Cascoded LDO Output Drivers for Fast Response and Low Quiescent Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional low drop-out (LDO) regulators face challenges in achieving fast response times and minimizing standby and quiescent current flow, especially in battery-operated products that operate over a wide range of supply voltages and temperatures.
Innovation Solution
The proposed solution involves an on/off output stage with a cascoded structure driven by shifting capacitors, eliminating the need for a level shifter and charge pump. This design includes two symmetrical drivers operating in alternation, a small boost pump, and a phase generator to manage operation phases, resulting in improved response time and reduced current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional LDO regulator structure is used, then voltage regulation is achieved, but response time is slow
Solution Approach 1:
The output stage is divided into multiple parallel drivers (first driver, second driver, third driver, fourth driver) that operate in alternating phases. This segmentation allows the circuit to achieve fast response times by having multiple drivers ready to act simultaneously or in rapid succession, while each individual driver can be optimized for efficiency.
Solution Approach 2:
The drivers are controlled to operate in periodic alternating phases through the phase generator and clock signal. The first and second drivers operate in one phase while the third and fourth drivers operate in another phase, creating a periodic switching pattern that maintains fast response capability while reducing average current consumption.
2Use of energy by moving object
If conventional charge pump and level shifter are used, then voltage pumping is achieved, but area and current consumption increase
Solution Approach 1:
The patent extracts and removes the conventional charge pump and level shifter components from the circuit. Instead, it uses a simplified voltage pumping mechanism through the cascoded driver structure with capacitive coupling, which significantly reduces both the area occupied and the current consumption while maintaining the essential voltage regulation function.
Solution Approach 2:
The patent applies different operational modes to different drivers based on local conditions. The first driver operates in a first mode while the second driver operates in a second mode, allowing optimization of current consumption and area usage in different parts of the circuit according to their specific functional requirements.
3Reliability
If output driver gate is continuously refreshed, then driver performance is maintained, but current consumption increases
Solution Approach 1:
The gate refreshing is performed periodically rather than continuously. The phase generator controls the timing of gate refresh operations to coincide with specific phases of the driver operation, ensuring that drivers are refreshed only when necessary to maintain performance while minimizing the time that refreshing current is drawn.
Solution Approach 2:
The gates are refreshed in advance during idle phases before they are needed for high-current operation. This preliminary action ensures that the drivers are ready to operate at full performance when required, while the actual refreshing current is drawn during low-demand periods, reducing overall standby current consumption.
Data Source
AI summary
A LDO regulator circuit comprises an input comparator and driver circuitry including transistors having a current flow path therethrough coupled to an output node of the regulator. First and second driver each comprises: driver transistors having the current flow paths therethrough coupled to the output node, capacitive boost circuitry that applies to the drive transistors a voltage-pumped replica of the comparison signal. Voltage refresh transistor circuitry coupled to the capacitive boost circuitry transfer thereon the voltage-pumped replica. The first and second drivers can be controllably switched between a first mode of operation, during which the current flow path through the driver transistors is conductive or non-conductive based on the voltage-pumped replica of the comparison signal, and a second mode, during which the voltage refresh transistor circuitry is activated to transfer the voltage-pumped replica of the comparison signal, and the current flow path through the driver transistors is non-conductive.