DRAM Sense Amplifier Over-Drive Control Circuit
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Solution Overview
Problem
Existing semiconductor devices with low power supply voltage face challenges in high-speed operation due to insufficient switching performance of PMOS and NMOS transistors, leading to delayed voltage amplification and increased sensitivity to source voltage variations, which are exacerbated by manufacturing variations and the complexity of over-drive control circuits.
Innovation Solution
Implementing a semiconductor device with a sense amplifier that includes a power supply circuit, a sense amplifier dummy circuit, and a power supply control circuit to precisely control over-drive operations by varying power supply voltages over time, using both over-drive methods for PMOS and NMOS transistors to enhance amplification feedback and reduce the impact of element performance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power supply voltage of the sense amplifier is set to a low voltage to suppress power consumption, then power consumption is reduced, but the switching performance of transistors becomes insufficient and the operation speed is delayed
Solution Approach 1:
The patent applies preliminary action by providing an over-drive power supply voltage to the sense amplifier before the normal read operation begins. This initial high voltage boost prepares the transistors for optimal switching performance, ensuring that when the normal low voltage operation starts, the transistors are already in a state that enables fast response. The over-drive phase pre-charges the internal nodes and positions the transistors in their最佳 operating region, thereby resolving the contradiction between low power consumption and fast operation speed.
2Use of energy by moving object
If the power supply voltage is low, then power consumption is reduced, but the sense amplifier becomes highly sensitive to source voltage variations which adversely influences high-speed operation
Solution Approach 1:
The patent implements beforehand cushioning by introducing an over-drive power supply voltage that creates a buffer or cushion against voltage variations. During the over-drive phase, the elevated voltage provides a safety margin that compensates for potential fluctuations in the power supply. This cushioning effect ensures that even when the sense amplifier operates at low voltage to reduce power consumption, it remains robust against voltage variations and maintains reliable high-speed operation.
3Speed
If an over-drive method is used to improve switching performance, then sufficient current supply capability is attained and operation speed increases, but the complexity of controlling the over-drive timing increases
Solution Approach 1:
The patent applies self-service by designing the over-drive control mechanism to automatically manage its own timing without requiring complex external control circuits. The sense amplifier's internal nodes and transistor states naturally indicate when over-drive is needed and when it should be terminated. This self-managing approach allows the system to achieve fast operation speed through over-drive while minimizing the complexity of control circuits, as the system essentially controls itself based on its internal state.
Data Source
AI summary
A semiconductor device includes a DRAM cell configured to store a data; and a sense amplifier activated in response to supply of power supply voltages and configured to sense the data stored in the DRAM cell. A power supply circuit supplies the power supply voltages to the sense amplifier. A sense amplifier dummy circuit provides a replica of a state of the sense amplifier immediately after the activation of the sense amplifier; and a power supply control circuit controls the power supply circuit based on the replica such that the power supply voltages are varied with time.