Semiconductor Integrated Circuit Threshold Voltage Control
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Solution Overview
Problem
Conventional semiconductor integrated circuits face challenges in reducing power consumption in standby mode while minimizing noise and leakage current, as the use of high threshold voltage transistors for switching can cause ground bounce noise and inefficient current supply.
Innovation Solution
The semiconductor integrated circuit incorporates a logic circuit portion with NMOS and PMOS transistors of different threshold voltages, along with a control mechanism that applies bulk voltages to adjust the threshold voltage of these transistors, ensuring high threshold voltages are maintained in standby mode to block leakage current and transition smoothly to low threshold voltages during active states to reduce noise and enhance current supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a device is scaled down to improve performance and reduce power consumption, then operation speed is improved and power consumption is reduced, but threshold voltage increases causing the transistor to not turn off completely resulting in large leakage current
Solution Approach 1:
The patent applies different threshold voltages to different transistors within the same circuit. Specifically, it uses low threshold voltage transistors for drive transistors to ensure fast switching and high-speed operation, while using high threshold voltage transistors for switch transistors to minimize leakage current when off. This local differentiation of transistor characteristics resolves the contradiction between speed and leakage.
Solution Approach 2:
The patent changes the threshold voltage parameter of transistors based on their functional requirements. By selecting transistors with appropriate threshold voltages for different circuit positions and dynamically controlling threshold voltage through body biasing, the patent optimizes both operation speed and leakage current characteristics simultaneously.
2Loss of energy
If high threshold voltage transistors are used to reduce leakage current in standby mode, then leakage current is reduced, but noise increases and current supply becomes inefficient during active state
Solution Approach 1:
The patent dynamically adjusts the threshold voltage of transistors based on the operational state of the circuit. During standby mode, high threshold voltage is maintained to minimize leakage current. During active state, the threshold voltage is reduced to improve current supply efficiency and minimize noise. This dynamic adaptation resolves the contradiction between leakage reduction and noise generation.
Solution Approach 2:
The patent employs periodic switching between different threshold voltage states corresponding to standby and active modes. The body bias voltage is periodically adjusted to match the operational requirements, ensuring low leakage during standby and low noise during active operation.
3Loss of energy
If threshold voltage is lowered to maintain complete transistor turn-off, then leakage current is reduced, but operation speed decreases significantly
Solution Approach 1:
The patent assigns different threshold voltage characteristics to different transistors based on their specific functions. Drive transistors use low threshold voltage to ensure fast switching and high-speed operation, while switch transistors use high threshold voltage to ensure complete turn-off and minimal leakage current. This localized optimization resolves the speed-leakage trade-off.
Data Source
AI summary
A semiconductor integrated circuit with low power consumption is provided. In one embodiment, the semiconductor integrated circuit includes a logic circuit portion that is connected between a first power line and a virtual ground line. The logic circuit portion includes at least one NMOS transistor having a first threshold voltage and at least one PMOS transistor having a second threshold voltage. The semiconductor integrated circuit further includes a first MOS transistor, which is connected between the virtual ground line and a ground voltage, where the first MOS transistor has the first threshold voltage and applies the ground voltage to the virtual ground line in an active state. Also included in the semiconductor integrated circuit is a controller that is connected to the first MOS transistor, where the controller applies the ground voltage to the first MOS transistor in the active state and applies a bulk voltage supplied from a bulk power line in a standby state to control a threshold voltage of the first MOS transistor.