Self-adjustable Current Source Control Circuit for LDO Regulators
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Solution Overview
Problem
Low-dropout (LDO) regulators face inefficiencies due to continuous power consumption and heat generation from control circuitry during high load current conditions, as existing solutions require complex and continuously active control circuits to manage sink current.
Innovation Solution
A self-adjustable current source control circuit using a replica output stage transistor, a reference current source, and a negative feedback circuit that automatically turns off the sink current during high load conditions, reducing power consumption and heat generation without needing a complex control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current source circuitry is continuously active to maintain regulated output voltage, then output voltage stability is improved, but power consumption and heat generation increase during high load conditions
Solution Approach 1:
The current source circuitry transitions from a static continuously-active state to a dynamic state that automatically adjusts based on load conditions. The patent employs voltage-dependent control where the current source activation level is dynamically determined by the voltage difference between the output terminal and a reference terminal, enabling the circuit to adapt its power consumption characteristics to match actual regulatory needs.
Solution Approach 2:
The patent implements a feedback mechanism where a portion of the output voltage is fed back to control the current source circuitry. The control voltage is generated by comparing the output voltage with a reference voltage, and this feedback signal automatically adjusts the current source activation level, creating a closed-loop system that responds to load conditions without requiring complex external control circuits.
2Use of energy by moving object
If complex control circuitry is used to turn off sink current during high load conditions, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The current source control circuit is designed to be self-regulating, using the regulator's own output voltage to control its operation. The patent eliminates the need for external control circuits by having the current source circuitry automatically respond to voltage conditions at the output terminal, making the system self-sufficient and avoiding additional complexity.
Solution Approach 2:
The patent integrates multiple functions into the existing regulator components. The differential amplifier serves both its traditional error correction function and additionally controls the current source circuitry. The output stage transistor simultaneously performs voltage regulation and current sourcing functions, reducing the need for separate dedicated control circuits.
Data Source
AI summary
A self-adjustable current source control circuit utilizes a replica output stage, a sink current source that generates a reference current, and a negative feedback circuit to generate a sink current between a linear regulator output terminal and ground only when a load circuit connected to the linear regulator is in a low power consuming state. The replica output stage includes an 1:N scaled replica of the linear regulator's NMOS (or NPN) output stage transistor, and the negative feedback circuit utilizes two PMOS (or PNP) negative feedback transistors having the same N:1 size ratio and connected as a common gate amplifier, whereby one of the two negative feedback transistors turns on to draw the desired sink current from the regulator output terminal only when the load current falls below N times the reference current (i.e., only the load current is drawn through the output stage transistor during high load current conditions).