Back-Bias Generator Circuit for Full-Range Voltage Control
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Solution Overview
Problem
Current transistor designs, particularly those with back-gate terminals, face limitations in applying a full range of positive and negative voltages, restricting their ability to operate in both forward and reverse back-bias modes simultaneously, which hampers the adjustment of threshold voltage and efficiency in power, performance, and area (PPA) optimization.
Innovation Solution
A circuit structure comprising multiple voltage generators, multiplexer cells, and a digital-to-analog converter (DAC) that generates and controls a full range of biasing voltages from −1.8V to 1.8V at a single output node, enabling transistors with back-gate terminals to operate in forward and reverse back-bias modes by multiplexing positive and negative voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a full range of positive and negative voltages is applied to the back-gate terminal, then the threshold voltage can be precisely controlled and transistors can operate in both forward and reverse back-bias modes, but the circuit complexity increases due to the need for multiple voltage generators and multiplexer cells
Solution Approach 1:
The voltage generation function is segmented into multiple independent voltage generators (first voltage generator for positive voltage, second voltage generator for negative voltage), each capable of operating independently. This segmentation allows the circuit to provide full-range back-bias voltages while maintaining modular architecture, resolving the contradiction between voltage range and circuit complexity.
Solution Approach 2:
The circuit employs multiplexer cells that dynamically switch between different voltage sources based on control signals from the DAC. This dynamic switching capability enables the circuit to adaptively provide the required voltage range without permanently connecting all voltage generators, thereby reducing the effective circuit complexity while maintaining full adaptability.
2Measurement precision
If multiple voltage generators and multiplexer cells are used to provide full-range back-bias voltages, then precise threshold voltage control is achieved, but the device area increases
Solution Approach 1:
Each voltage generator is designed to be multi-functional, capable of providing both positive and negative voltage outputs. The multiplexer cells serve multiple functions by switching between different voltage sources and routing them to the back-gate terminal. This universality reduces the total number of dedicated components needed, thereby controlling circuit area while maintaining precise threshold voltage control capability.
3Productivity
If the threshold voltage is reduced to improve power consumption and drive strength, then the transistor can operate with smaller gate to source voltage and higher frequency, but the leakage or stand-by current increases when the transistor is off
Solution Approach 1:
The circuit enables dynamic adjustment of the threshold voltage parameter by applying variable back-bias voltages through the voltage generators and multiplexer system. This allows the threshold voltage to be optimized for different operating conditions - reduced for high-performance modes and increased for low-leakage modes - resolving the contradiction between transistor performance and leakage current through parameter modulation rather than structural changes.
Data Source
AI summary
Embodiments of the disclosure provide a circuit structure for producing a full range biasing voltage including: a logic control node; first and second voltage generators, coupled to the logic control node, the first and second voltage generators configured to generate a positive voltage output at a positive voltage node and a negative voltage output at a negative voltage node; first and second multiplexer cells, coupled to the logic control node, configured to multiplex the positive voltage level received from the first or the second positive voltage node and the negative voltage level received from the first or the second negative voltage node to provide a multiplexed output; and an output node coupled to each of the first multiplexer cell and the second multiplexer cell configured to receive the multiplexed output to provide a biasing voltage range to at least one transistor having a back-gate terminal.