Dynamic Charge Pump Control for Low Dropout Voltage Regulators
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Solution Overview
Problem
Current linear voltage regulators with NMOS pass devices face challenges in achieving low drop-out voltage while minimizing quiescent current consumption and die area, as they require large charge pump blocks that consume significant power and increase die size due to high voltage requirements.
Innovation Solution
The proposed solution dynamically switches charge pump blocks ON and OFF based on need, uses a multiple input floating gate NMOS pass device to lower the effective threshold voltage, and employs a filter to reduce switching noise, thereby reducing quiescent current consumption and optimizing regulator performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a charge pump block is used to generate high voltage for NMOS pass device gate drive, then the regulator can achieve low drop-out voltage, but the quiescent current consumption increases significantly
Solution Approach 1:
The charge pump block is operated periodically rather than continuously. A controller monitors the regulator output voltage and activates the charge pump only when the output voltage drops below a threshold, indicating insufficient gate drive voltage. This periodic operation dramatically reduces quiescent current while maintaining the ability to achieve low drop-out voltage when needed
Solution Approach 2:
The system dynamically adjusts the charge pump operation based on real-time regulator performance. The controller adapts the charge pump activation timing and duration according to load conditions and output voltage levels, optimizing the balance between maintaining low drop-out capability and minimizing power consumption
2Area of stationary object
If a large charge pump block is used to ensure sufficient voltage drive, then the regulator maintains stability, but the die area increases
Solution Approach 1:
The charge pump functionality is segmented into a compact integrated block rather than a large discrete implementation. The charge pump is designed with minimal capacitance values and optimized transistor sizing to reduce area while providing sufficient voltage multiplication capability for gate drive, thereby reducing die area without compromising regulator stability
3Use of energy by moving object
If switching charge pump blocks ON and OFF dynamically, then quiescent current is reduced, but switching noise is introduced
Solution Approach 1:
A noise filtering network is introduced as an intermediary between the switching charge pump block and the regulator output. This filtering network attenuates the high-frequency switching noise generated by the charge pump while allowing the useful gate drive voltage to pass through, thereby reducing quiescent current through dynamic switching without significantly introducing harmful switching noise to the regulated output
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces quiescent current consumption by averaging charge pump current, allows for smaller transistor sizes, and minimizes die area while maintaining low drop-out voltage and improved transient performance, resulting in more efficient and competitive voltage regulators.
Implementation Method 1
a charge pump block (213) that includes associated circuits like an oscillator etc.
Implementation Method 2
filtering a charge pump output to reduce an impact of a switching noise of the charge pump on a regulator output
Data Source
AI summary
A charge pump driven Linear Voltage Regulator (LVR) system with a cascoded n-type output pass device includes an error amplifier; a voltage feedback network; a dynamically controlled charge pump block that is ON only when required and OFF otherwise; a gate drive system configured to ensure that the charge pump drives only gate of a cascode transistor and no DC or static current load such that a voltage is preserved for a duration; and a filter at the charge pump output to reduce an impact of the switching noise of the charge pump on the regulator output, wherein the filter is outside a main servo loop of the regulator, wherein an n-type pass element and/or cascode element in the cascoded n-type output pass device comprises at least one of a Metal Oxide Semiconductor (MOS) Field Effect Transistor (FET), a bipolar junction transistor, an LDMOS, or a FinFET device.