Reconfigurable Series-Shunt LDO for PSRR and Reverse Isolation
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Solution Overview
Problem
Conventional low-dropout regulators (LDOs) face a trade-off between achieving high power-supply rejection ratio (PSRR) and good reverse isolation, often sacrificing one performance for the other, and may consume excessive power.
Innovation Solution
The development of LDOs with a core circuitry and a reverse isolation circuitry that are configured to provide high PSRR and good reverse isolation simultaneously, with the reverse isolation circuitry being configurable to adjust current flow in response to output node ripples, allowing for a trade-off between power consumption and leakage current, and featuring a transistor structure with a gate voltage controlled by the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LDO design is used to achieve high PSRR, then power-supply rejection ratio is improved, but reverse isolation deteriorates
Solution Approach 1:
The LDO is divided into two independent circuits: a core LDO circuit responsible for voltage regulation and PSRR, and a separate reverse isolation circuit responsible for blocking reverse current. This segmentation allows each circuit to optimize its specific function without compromising the other, achieving both high PSRR and good reverse isolation simultaneously.
Solution Approach 2:
A reverse isolation circuit is introduced as an intermediary component between the output node and ground. This circuit acts as a mediator that selectively blocks reverse current while allowing the core LDO circuit to maintain its voltage regulation function, thus improving reverse isolation without affecting PSRR.
2Object-generated harmful factors
If reverse isolation circuitry is added to improve reverse isolation, then reverse isolation is improved, but power consumption increases
Solution Approach 1:
The reverse isolation circuit employs dynamic control through a control signal that adjusts the isolation strength based on operating conditions. The circuit can switch between different isolation modes (e.g., different transistor configurations) to optimize the trade-off between reverse isolation performance and power consumption, rather than maintaining fixed isolation throughout all operating states.
Solution Approach 2:
The reverse isolation circuit allows dynamic adjustment of key parameters such as the isolation current and transistor gate voltages. By changing these parameters based on system requirements, the circuit can achieve high reverse isolation when needed while reducing power consumption during normal operation, thus resolving the contradiction between isolation performance and power usage.
3Object-generated harmful factors
If reverse isolation circuitry responds quickly to ripples, then reverse isolation is improved, but bandwidth requirements increase
Solution Approach 1:
The frequency response is segmented between the core LDO circuit and the reverse isolation circuit. The core circuit handles low-frequency regulation with limited bandwidth, while the reverse isolation circuit specifically targets high-frequency ripple suppression. This segmentation allows the reverse isolation circuit to respond quickly to ripples without requiring the entire LDO system to have high bandwidth across all frequencies.
Solution Approach 2:
The reverse isolation circuit provides excessive isolation capability at high frequencies where ripples occur, while the core circuit maintains adequate low-frequency regulation. This partial focus on specific frequency ranges allows the system to achieve effective ripple suppression without the penalty of requiring high bandwidth across the entire frequency spectrum.
Data Source
AI summary
A low-dropout regulator (LDO) capable of providing high power-supply rejection ratio (PSRR) and good reverse isolation. The LDO may include a core circuitry and a reverse isolation circuitry. The core circuitry may include a PSRR circuitry coupled to an output node and configured to provide high PSRR at the output node. The reverse isolation circuitry may be configured to provide good reverse isolation at the output node by, for example, providing current in response to ripples at the output node. The reverse isolation circuitry may be configured with bandwidth higher than that of the core circuitry such that it can provide fast transient response. The reverse isolation circuitry may be configurable and/or reconfigurable for a desirable reverse isolation performance. The reverse isolation circuitry may be configurable and/or reconfigurable to trade off between power consumed by the reverse isolation circuitry and a leakage current flowing through the core circuitry.