Boosting LDO Regulator With Voltage-Drop Compensation
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Solution Overview
Problem
Conventional low-dropout regulators face challenges in maintaining a stable output voltage during transient high load conditions in gate driver applications, requiring high bandwidth and increased current consumption or large capacitance, which is not feasible in integrated circuit implementations.
Innovation Solution
A high-speed low-impedance boosting low-dropout regulator is designed with a differential amplifier, feedback circuit, and a compensation stage to provide a first output current and a boosted output current during different intervals, compensating for voltage drops and reducing output impedance through complementary control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the bandwidth of conventional low-dropout regulator is increased to 100 MHz to handle switching transient, then the dynamic performance of gate driver is maintained, but the average current consumption is substantially increased
Solution Approach 1:
The regulator dynamically switches between two operational modes: a high-bandwidth mode for handling transient load changes and a low-bandwidth mode for steady-state operation. The mode selection is controlled by detecting the rate of change of the output voltage, enabling the system to adapt its bandwidth characteristic to the instantaneous operating conditions, thus achieving fast response only when necessary and reducing average current consumption during normal operation
Solution Approach 2:
The patent changes the bandwidth parameter of the regulator based on operating conditions. By detecting dV/dt and switching between different bandwidth settings (100 MHz for transients, lower for steady-state), the system optimizes the trade-off between dynamic performance and power consumption, achieving high-speed response only when load transients occur
2Stability of the object's composition
If bypass capacitance is increased to supply necessary current during transient events, then output voltage stability is improved, but the circuit becomes incompatible with integrated circuit implementation and increases pin count and board area
Solution Approach 1:
The patent extracts the function of large bypass capacitance from the physical capacitor component and implements it through an active current boosting circuit. By using a booster amplifier to generate compensating current during transients, the system achieves voltage stability without requiring large external capacitors, thereby eliminating the need for additional pins and reducing PCB area while maintaining integrated circuit compatibility
Solution Approach 2:
The patent replaces the passive mechanical/electrical solution of large bypass capacitance with an active electronic control system. The booster amplifier and control circuitry dynamically generate compensating current to maintain output voltage stability, substituting the static energy storage approach with a dynamic current generation approach that is more suitable for integrated circuit implementation
3Speed
If booster amplifier is used to generate boost current in response to output voltage drop, then the response to transient load is improved, but a substantial glitch of regulator output voltage occurs due to voltage drop required to trigger boost current
Solution Approach 1:
The patent implements preliminary action by detecting the rate of change of output voltage (dV/dt) and proactively activating the booster amplifier before a significant voltage drop occurs. This predictive approach allows the system to prepare compensating current in advance, preventing voltage glitches rather than reacting to them, thus maintaining both fast response and output voltage stability
Solution Approach 2:
The patent uses feedback by continuously monitoring the output voltage and its rate of change. The dV/dt detection circuit provides feedback about transient conditions, enabling the control system to activate the booster amplifier at the optimal moment. This feedback mechanism ensures that boost current is generated based on actual transient needs, preventing both over-response (glitches) and under-response (poor transient handling)
Data Source
AI summary
A method for regulating a voltage reference signal includes providing a first output current during a first interval and a boosted output current during a second interval to generate a low-dropout voltage reference signal based on a first power supply voltage, a second power supply voltage, and a reference voltage level. The method includes, during the second interval, compensating for a voltage drop caused by providing the boosted output current. The first output current may be provided in a first mode of operation. The boosted output current and voltage drop compensation may be provided in a boosted mode of operation.