Multiple-Input Regulator Circuit With Single NFET Power Paths
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Solution Overview
Problem
Conventional multiple input LDO regulator circuits require multiple power transistors in series, leading to increased integrated circuit device area and higher costs due to the need for power multiplexers to select and isolate input power sources, which also results in back power leakage.
Innovation Solution
The proposed solution involves a regulator circuit configuration with a single power transistor in each power path, using switches to connect the body terminal of the transistor to ground potential based on enable signals, allowing for power source selection and regulation while preventing back power leakage, and utilizing a single NFET device instead of PFET to minimize device area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple power transistors are used in series in the power path for power source selection, then the power source selection and isolation function is achieved, but the integrated circuit device area increases significantly
Solution Approach 1:
The patent combines the power source selection function and the power isolation function into a single power transistor per path. The power transistor serves dual purposes: conducting power when selected and isolating the power path when not selected, eliminating the need for separate isolation transistors and reducing overall device area.
Solution Approach 2:
Each power transistor is designed to perform multiple functions: it acts as the primary power conduction element when its associated power source is selected, and simultaneously serves as the isolation element for unselected power paths. This multi-functionality reduces the total number of transistors required in the circuit.
2Reliability
If multiple power transistors are used in series for power path selection, then the power isolation function is achieved, but back power leakage occurs from active to inactive power paths
Solution Approach 1:
The patent extracts the isolation function from being a separate component and integrates it directly into the power transistor's operation. By controlling the gate voltage of each power transistor, the isolation capability is achieved through the transistor's inherent off-state characteristics, eliminating the need for additional isolation transistors and reducing back power leakage paths.
3Adaptability or versatility
If PFET devices are used for power conduction, then the power source selection function is achieved, but the device area is larger compared to NFET devices
Solution Approach 1:
The patent changes the transistor type parameter from PFET to NFET for the power conduction transistors. NFET devices generally occupy less area than PFET devices for the same current handling capability. This parameter change maintains the power conduction function while reducing the overall device area of the integrated circuit.
Data Source
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AI summary
The embodiments described herein relate to an improved circuit technique for a multiple input regulator circuit having multiple power paths therein. The multiple input regulator circuit may be configured to minimize integrated circuit area by utilizing a single power transistor in the power path from each of the power sources to the output of the regulator circuit. The single power transistor is adapted to provide both power source selection and power source regulation functions, thus replacing the power selection transistor and the power regulation transistor of conventional designs.