Bootstrapped Multiplexer Circuit for Low-Voltage Read Current
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Solution Overview
Problem
Conventional multiplexer circuits face challenges in maintaining high-speed operation due to power supply headroom limitations, particularly in low voltage applications, which degrades their ability to generate sufficient read currents and slows down read speeds.
Innovation Solution
The proposed multiplexer circuit employs a combination of low voltage and high voltage NMOS transistors, along with native transistors, to utilize bootstrapping and increase current flow, thereby maintaining high-speed operation without increasing transistor size, and includes a discharge circuit to ensure bootstrapping occurs at the start of each read cycle and a disable circuit to reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high voltage transistors with thick gate oxides and high threshold voltages are used in multiplexer pass devices, then high voltage isolation is provided, but power supply headroom is limited and read current generation is insufficient
Solution Approach 1:
The pass device is segmented into multiple transistor stages (first pass transistor, second pass transistor, and native transistor) connected in series. This segmentation allows each transistor to handle a portion of the voltage and current requirements, enabling high voltage isolation while maintaining sufficient power headroom for read current generation through the distributed architecture.
Solution Approach 2:
The invention changes the electrical parameters of the transistor chain by using native transistors with zero threshold voltage and configuring the gate connections to create voltage multiplication effects. This parameter transformation allows the system to achieve both high voltage isolation and adequate power headroom by dynamically adjusting the effective threshold voltages and gain characteristics of the transistor stages.
2Speed
If transistor size is increased to improve read speed, then read current generation is enhanced, but area consumption increases
Solution Approach 1:
Native transistors are introduced as intermediary elements between the control logic and the pass transistors. These native transistors act as voltage amplifiers that boost the gate drive voltage to the pass transistors, enabling higher read currents and faster read speeds without requiring larger transistor dimensions. The intermediary native transistors provide the necessary voltage multiplication to drive the pass devices more effectively.
3Use of energy by moving object
If low voltage operation is implemented to reduce power consumption, then power efficiency is improved, but read current generation becomes insufficient
Solution Approach 1:
The invention transforms the voltage parameters through the native transistor stage, which provides voltage multiplication and boosting. Even though the supply voltage is low, the native transistor configuration creates higher effective gate voltages that drive the pass transistors to generate sufficient read currents. This parameter transformation allows low voltage operation to coexist with adequate read current generation capability.
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 solution enables high-speed operation with low power consumption and high voltage isolation, improving read speeds and reducing area consumption, while effectively addressing power supply headroom limitations and leakage issues.
Implementation Method 1
The multiplexer circuit utilizes bootstrapping to provide high speed operation in the presence of low power supply. The native transistors are coupled to the pass transistors for increasing a control voltage supplied to a gate terminal of the pass transistors.
Data Source
AI summary
A multiplexer circuit provided herein includes a plurality of pass devices coupled in parallel between a power supply and a ground supply. According to one embodiment, each pass device may include a first pair of transistors, which is coupled in series between the power supply and the ground supply, and a second pair of transistors, which is coupled to the first pair of transistors for controlling a current passed there through. In general, the second pair of transistors may be configured for increasing the amount of current passed through the first pair of transistors. For example, the second pair of transistors may utilize a bootstrapping effect to increase a pair of control voltages supplied to the gate terminals of the first pair of transistors. The increased control voltages function to over-drive the gate terminals of the first pair of transistors, thereby increasing the amount of current passed there through. A memory device comprising the multiplexer circuit and method for operating the multiplexer circuit are also provided herein.