Voltage-Mode LDO Control Node Circuit for Low Quiescent Current
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Solution Overview
Problem
Current voltage regulator circuits, particularly low-dropout (LDO) regulators, face challenges in reducing quiescent current consumption, especially in low-power modes and when operating in the dropout region, leading to high power dissipation and stability issues due to complex sensing networks and dynamic biasing limitations.
Innovation Solution
The proposed solution involves a voltage regulator circuit that adjusts the voltage level of a control node by sourcing and sinking currents, using a switch device coupled between the input and regulated power supply nodes, with a control circuit generating feedback signals and error signals to dynamically adjust the current, thereby reducing quiescent current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LDO regulators use complex sensing networks and dynamic biasing to maintain regulation, then voltage regulation stability is improved, but quiescent current consumption increases
Solution Approach 1:
The patent extracts and removes the complex sensing networks and dynamic biasing circuits from the LDO regulator, replacing them with a simplified control mechanism that uses a small capacitor at the control node to achieve voltage regulation with minimal quiescent current consumption
Solution Approach 2:
The patent changes the operating parameters by using a small capacitor to rapidly change the control node voltage, enabling the regulator to achieve both stability and low quiescent current by operating in a different regime than conventional LDOs
2Loss of energy
If LDO regulators operate in the dropout region to reduce voltage headroom, then power supply efficiency is improved, but regulation stability deteriorates
Solution Approach 1:
The patent introduces dynamic behavior through the small capacitor at the control node, which can rapidly change voltage in response to load changes, enabling stable regulation even when operating in the dropout region where conventional LDOs would fail
3Measurement precision
If conventional regulators use continuous biasing circuits to maintain control voltage, then regulation precision is improved, but power consumption increases
Solution Approach 1:
The patent replaces continuous biasing with periodic action through the small capacitor that charges and discharges in response to error signals, providing precise voltage control only when needed rather than maintaining continuous current flow
Solution Approach 2:
The control node capacitor serves itself by maintaining voltage through its stored charge and only requiring brief current injections from the pass transistor to correct deviations, eliminating the need for external continuous biasing circuits
Data Source
AI summary
A voltage regulator circuit includes a switch device that is coupled between an input power supply and a regulated power supply node. The voltage regulator circuit adjusts a value of a current flowing from the input power supply to the regulated power supply node by modifying a voltage level of a control node coupled to the switch device. A control circuit adjusts the voltage level of the control node using an error signal based on a comparison of the voltage level of the regulated power supply node and a reference voltage. To improve the response time of the voltage regulator circuit to changes in load current, the control circuit additionally sources current to and/or sinks current from the control node based on a voltage level of the control node.