Power Supply Clamping via Transistor Segmentation
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Solution Overview
Problem
Existing power supply technologies face challenges in efficiently regulating output voltage when the input supply voltage falls below a certain threshold, leading to increased silicon area requirements for the output pass device to minimize resistance and voltage drop, and failing to fully open the device results in significant silicon area usage.
Innovation Solution
A power supply design featuring a first and second transistor in a mirror configuration, a cutoff switch, a comparator for comparing feedback port voltage with a fixed reference voltage to control the cutoff switch, and a third transistor controlled by a second comparator to manage gate voltage, allowing for efficient pass-through mode operation and reduced silicon area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the output pass device is made large to minimize resistance and voltage drop, then the voltage drop across the device is reduced, but the silicon area required increases significantly
Solution Approach 1:
The patent divides the output pass device into two separate transistors: a first transistor that handles the majority of the load current, and a second transistor that provides fine-grained control for voltage regulation. This segmentation allows each transistor to be optimized for its specific function, reducing the total silicon area while maintaining low voltage drop.
Solution Approach 2:
The first transistor is designed to handle excessive current capacity beyond what is needed for precise regulation, while the second transistor provides the precise control. This partial action approach allows the main current-carrying device to be smaller than it would need to be if it had to provide both high current capacity and fine control.
2Area of stationary object
If the output pass device is made small to reduce silicon area, then the silicon area is minimized, but the resistance and voltage drop increase
Solution Approach 1:
By segmenting the pass device into two transistors, the patent allows the first transistor to be optimized for low resistance and high current capacity with minimal area, while the second transistor handles the control function. This resolves the contradiction by showing that area can be reduced while maintaining low voltage drop through functional division.
3Device complexity
If the first transistor remains connected when feedback voltage is low, then the circuit remains simple, but excessive current drainage occurs when in pass-through mode
Solution Approach 1:
The patent uses a comparator to monitor the feedback voltage and control the cutoff switch. When the feedback voltage drops below a threshold indicating pass-through mode, the comparator triggers the cutoff switch to disconnect the first transistor from the power supply, preventing excessive current drainage. This feedback mechanism adds minimal complexity while effectively solving the current drainage problem.
4Loss of energy
If the cutoff switch is added to disconnect the first transistor, then current drainage is prevented, but the device complexity increases
Solution Approach 1:
The cutoff switch is controlled by a comparator that monitors the feedback voltage, creating a simple feedback-based control system. This approach prevents excessive current drainage during pass-through mode while adding minimal circuit complexity, as the comparator and switch are standard components that integrate easily into the existing regulator architecture.
Data Source
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AI summary
A power supply is disclosed. The power supply includes a first switch and a second switch. The gate of the first switch is coupled to the gate of the second switch. The power supply further includes a cutoff switch coupled between the first switch and an input voltage port. A comparator is included for comparing a voltage at a feedback port with a fixed reference voltage. The comparator opens the cutoff switch when the voltage at the feedback port is lower than the fixed reference voltage.