LDO Architecture With DAC Current for Voltage Undershoot Mitigation
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Solution Overview
Problem
Low-power Dynamic Voltage Scaling (DVS) systems face voltage undershoot issues during transitions from high to low voltage, causing digital circuits to malfunction due to LDO load current and output capacitance, which existing comparative LDO architectures fail to adequately mitigate.
Innovation Solution
Incorporating a digital-to-analog converter (DAC) to modify the load current generated by a low-dropout regulator, allowing for controlled voltage transitions and reducing undershoot by adjusting the DAC current based on control inputs, thereby stabilizing the output voltage during voltage level changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a low-dropout regulator is used in low-power Dynamic Voltage Scaling systems, then power consumption is reduced, but voltage undershoot occurs during transitions from high to low voltage
Solution Approach 1:
The patent applies preliminary action by detecting the start of a voltage transition before the undershoot occurs and activating a compensatory current source in advance. The system monitors the LDO output voltage and, upon detecting a transition from high to low voltage, enables a current source that injects current into the output node to counteract the impending undershoot, thereby preventing the voltage from dropping below the minimum threshold
Solution Approach 2:
The patent implements preliminary anti-action by introducing a compensatory current that opposes the undershoot effect before it fully manifests. The current source is activated at the detection of voltage transition and provides an opposing current flow that counterbalances the load current's effect on the output voltage, preventing the harmful undershoot from occurring
2Reliability
If multiple on-chip LDOs are employed to mitigate undershoot, then voltage stability is improved, but device complexity and external component cost increase
Solution Approach 1:
The patent applies self-service by enabling a single LDO to compensate for its own undershoot through an integrated current source and control circuitry. The system monitors its own output voltage and automatically activates the compensatory current mechanism when a transition is detected, eliminating the need for multiple LDOs or external compensation components
Solution Approach 2:
The patent implements multi-functionality by designing a circuit where a single LDO performs both voltage regulation and self-compensation functions. The integrated current source and control logic enable the same LDO to handle both its primary regulation task and the compensatory action needed to mitigate undershoot, replacing the need for multiple specialized components
3Quantity of substance
If capacitorless LDO design is used, then external component count is reduced, but undershoot mitigation capability is weakened
Solution Approach 1:
The patent applies self-service by providing the LDO with an integrated compensatory current source and control circuitry that enables it to mitigate its own undershoot without relying on external capacitors. The system detects voltage transitions and automatically activates the current source to counteract undershoot, making the LDO self-sufficient in addressing its inherent instability
4Reliability
If DAC current is used to modify load current, then undershoot is mitigated, but device complexity increases
Solution Approach 1:
The patent introduces a DAC as an intermediary component that translates digital control signals into analog current adjustments. The DAC receives digital codes from a controller and converts them into proportional currents that modify the LDO's load current, providing precise and programmable control over the compensatory current without requiring complex analog circuitry
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
The solution effectively mitigates voltage undershoot by up to 99.34% and reduces transition time by 69.23%, ensuring stable operation of digital circuits during voltage transitions while maintaining low power consumption.
Implementation Method 1
a digital-to-analog converter (DAC) configured to receive a control input, and output a DAC current to the low-dropout regulator based on the control input
Data Source
AI summary
A low-dropout regulator architecture with undershoot mitigation. In one embodiment, a system including a low-dropout regulator and a digital-to-analog converter (DAC). The low-dropout regulator is configured to generate a load current and output a voltage at an output node. The digital-to-analog converter (DAC) is configured to receive a control input, and output a DAC current to the low-dropout regulator based on the control input. The DAC current is configured to modify the load current and mitigate an undershoot of the voltage that is output at the output node while the voltage transitions from a high voltage level to a low voltage level.