Semiconductor Device Standby Power Reduction via Virtual Nodes
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Solution Overview
Problem
In normally-off computing systems using MRAM, peripheral circuits exhibit power consumption due to leak paths in the standby state, which is not present in the MRAM itself, necessitating a solution to reduce power consumption in these circuits.
Innovation Solution
The implementation of a semiconductor device with a row decoder and read/write circuit that utilize PMOS transistors and capacitors to manage power supply voltage, reducing leak current by controlling the pulse width of signal pulses and maintaining charge in virtual power supply nodes, thereby minimizing power consumption during standby states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If MRAM is used as nonvolatile memory in normally-off computing, then power consumption in standby state is reduced, but peripheral circuits still exhibit power consumption due to leak paths
Solution Approach 1:
The patent applies preliminary action by pre-charging virtual power supply nodes (VDD1, VDD2) to a voltage level before the active cycle begins. Capacitors (C1, C2) store charge on these virtual power supply nodes during the standby state, so that when the active cycle starts, the peripheral circuits can operate without immediate power supply, thereby reducing leak current consumption during standby.
Solution Approach 2:
The patent introduces virtual power supply nodes (VDD1, VDD2) as intermediaries between the main power supply and the peripheral circuits. These virtual power supply nodes act as mediators that can be independently controlled and charged during standby state, allowing the peripheral circuits to be isolated from the main power supply and thus reducing leak current while maintaining operational capability when needed.
2Productivity
If power supply voltage is continuously applied to peripheral circuits, then they can operate without interruption, but power consumption increases due to leak paths in standby state
Solution Approach 1:
The patent implements periodic action by applying power supply voltage to the peripheral circuits only during active cycles rather than continuously. The virtual power supply nodes are charged periodically before each active cycle, allowing the circuits to operate intermittently without continuous power supply, thereby reducing power consumption during standby states while maintaining operational capability when needed.
3Loss of energy
If voltage on word and column selection lines is reduced to minimize leak current, then power consumption decreases, but read disturb may occur
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the voltage level on word and column selection lines based on the operational state. During standby state, the voltage is reduced to minimize leak current, while during active cycles, the voltage is restored to appropriate levels for normal operation. This dynamic parameter adjustment allows the system to reduce power consumption without causing read disturb, as the low voltage condition only exists when no read operations are being performed.
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 effectively reduces power consumption in the standby state and prevents read disturb by maintaining a lower voltage level in word and column selection lines, allowing for quick reactivation and efficient operation without the need for additional clamp circuits.
Implementation Method 1
a first capacitor connected between the second node and a reference potential
Implementation Method 2
The first transistor is turned on in the initial stage of an active cycle, and is turned off by applying the power supply voltage to the second node
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first transistor of a first conductivity type, and a first logical circuit. The first transistor of the first conductivity type is connected between a first node to which a power supply voltage is applied and a second node. The first transistor is turned on in the initial stage of an active cycle, and is turned off by applying the power supply voltage to the second node. The first logical circuit is driven by the power supply voltage applied to the second node. The first logical circuit outputs a voltage which is lower than the power supply voltage in the active cycle based on an input signal supplied thereto.