Tunable Voltage Controller for Sub-Circuits Using Doped Well Biasing
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Solution Overview
Problem
Conventional methods for providing a standby voltage to sub-circuit blocks using external junction diodes or diode-connected transistors are not optimal, especially across fabrication process variations and different applications, failing to maintain power and area advantages.
Innovation Solution
A tunable voltage controller employing a diode-connected MOS transistor within a doped well of a substrate, with a biasing unit that selectively connects the doped well to various voltage sources or a variable voltage source to adjust the voltage drop across the transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external junction diode is used to provide standby voltage, then the standby voltage can be obtained, but the voltage drop is not optimal and the device occupies more area
Solution Approach 1:
The patent merges the diode function with the MOS transistor by connecting the diode in parallel with the transistor and utilizing the transistor's body effect. The doped well (body) of the MOS transistor is connected to a selectable voltage source, allowing the transistor to provide both switching functionality and diode-like voltage drop characteristics, thereby eliminating the need for a separate external diode component.
Solution Approach 2:
The MOS transistor is designed to perform multiple functions: it acts as a switch during normal operation and as a voltage reference/diode during standby mode. By making the doped well voltage selectable, the same transistor structure can provide different voltage drops suitable for both operating and standby conditions, achieving multi-functionality without additional components.
2Area of stationary object
If a diode-connected transistor is used to provide standby voltage, then the area is reduced, but the voltage drop is not optimal across fabrication process variations
Solution Approach 1:
The patent introduces dynamic adjustability to the previously static diode-connected transistor structure. The doped well voltage can be selectively changed between different voltage sources (e.g., ground or different potential), allowing the transistor's threshold voltage and resulting voltage drop to be adjusted dynamically. This compensates for fabrication variations by enabling post-fabrication tuning to achieve optimal voltage drop.
Solution Approach 2:
The invention changes the electrical parameters of the MOS transistor by varying the doped well voltage potential. This parameter change directly affects the transistor's threshold voltage and the voltage drop across it when used in a diode-connected configuration. By providing selectable voltage sources for the doped well, the system can adjust the voltage drop parameter to compensate for manufacturing process variations.
3Device complexity
If the doped well is connected to a fixed voltage source, then the circuit is simple, but the voltage is not tunable for different applications
Solution Approach 1:
The patent transforms the static doped well connection into a dynamic, selectable connection. Multiple voltage sources are provided with the doped well, and a selection mechanism (such as switches or fusible links) allows choosing different voltage sources based on the application requirements. This adds tunability while maintaining relatively simple circuit architecture.
Solution Approach 2:
The voltage controller is designed to serve multiple applications by providing a universal interface with selectable voltage sources. The same basic circuit structure can be configured for different voltage requirements (different applications) by simply changing which voltage source is connected to the doped well, achieving versatility without requiring multiple dedicated circuits.
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 allows for tunable and efficient voltage adjustment, maintaining power and area advantages while providing optimal standby voltage, reducing voltage drop and increasing flexibility across different applications and fabrication variations.
Implementation Method 1
A diode-connected MOS transistor contained in a doped well of a substrate is configured to provide a voltage for the sub-circuit
Implementation Method 2
a biasing unit configured to adjust the voltage by selectively connecting the doped well to one of a plurality of voltage sources or to a variable voltage source
Data Source
AI summary
The present invention provides a tunable voltage controller for use with a sub-circuit. In one embodiment, the tunable voltage controller includes a diode-connected MOS transistor contained in a doped well of a substrate and configured to provide a voltage for the sub-circuit. Additionally, the tunable voltage controller also includes a biasing unit configured to adjust the voltage by selectively connecting the doped well to one of a plurality of voltage sources or to a variable voltage source.