Sense Amplifier Power Decoupling for Stable DRAM Read Timing
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Solution Overview
Problem
The reduction in power voltage in semiconductor memory devices, such as DRAMs, leads to noise-induced instability and increased RAS to CAS delay time, particularly in bank compress mode operations, where multiple sense amplifiers operate simultaneously, causing power voltage drops and affecting device stabilization.
Innovation Solution
A circuit comprising a sense amplifying circuit, a power supplying unit, and a decoupling unit that generates and applies a decoupling noise independent of the power voltage to compensate for noise generated by peak currents during sense amplifier operation, using a driving circuit with serially connected inverters and an NMOS transistor type capacitor to maintain the decoupling noise for a predetermined period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple sense amplifiers operate simultaneously in bank compress mode, then productivity is improved, but power voltage stability deteriorates due to noise-induced drops
Solution Approach 1:
A decoupling capacitor is introduced as an intermediary energy storage element between the power voltage supply and the sense amplifiers. This capacitor acts as a local energy reservoir that mediates the power delivery, supplying instantaneous current during simultaneous sense amplifier operations without causing voltage drops on the main power supply line, thus maintaining power voltage stability while enabling high-productivity bank compress mode testing
Solution Approach 2:
The decoupling capacitor is pre-charged to the power voltage level before the sense amplifiers operate. This preliminary energy storage preparation allows the capacitor to immediately supply compensating current when multiple sense amplifiers are activated simultaneously, preventing voltage drops before they can affect circuit operation and maintaining stable power delivery during high-speed testing
2Use of energy by moving object
If power voltage is reduced to lower operating voltage, then energy consumption is improved, but noise susceptibility increases causing instability
Solution Approach 1:
The decoupling capacitor serves as an intermediary that isolates the low-voltage sense amplifier circuit from power supply noise. By providing a local energy reservoir, it prevents external noise from coupling into the sensitive low-voltage circuit while maintaining stable power delivery, thus enabling operation at reduced voltages without increasing noise susceptibility
3Reliability
If decoupling noise is generated to compensate power voltage drops, then power voltage stability is improved, but device complexity increases
Solution Approach 1:
The decoupling capacitor is connected to existing power supply nodes (power voltage and ground voltage) without requiring additional dedicated power supply circuits or control logic. This intermediary component achieves power voltage stabilization by leveraging already-available power rails, thus improving reliability while minimizing the increase in device complexity
Solution Approach 2:
The decoupling capacitor automatically performs noise compensation and voltage stabilization without requiring external control signals or active management. The capacitor self-charges and self-discharges in response to power demand fluctuations, providing autonomous voltage regulation that improves stability without adding complex control circuitry
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 inhibits power voltage drops and maintains stability, thereby preventing deterioration of RAS to CAS delay time even at low power voltages and in parallel test modes like bank compress mode.
Implementation Method 1
a decoupling unit generating a decoupling noise with a second power and providing the decoupling noise to the first power voltage
Implementation Method 2
employing serially connected inverters and an NMOS transistor type capacitor to provide decoupling noise
Data Source
AI summary
The present invention discloses a circuit providing a power for a sense amplifier that stabilizes a power voltage supplied to the sense amplifier by compensating a noise generated in the power voltage when the sense amplifier operates with an selectively generated decoupling noise. The circuit providing a power for a sense amplifier includes a sense amplifying circuit sensing and amplifying data loaded on a bit line with a first power. A power supplying unit provides the first power to the sense amplifying circuit. A decoupling unit generates a decoupling noise with a second power and provides the decoupling noise to the first power voltage. The decoupling noise is maintained for a period including a time point of an operation of the sense amplifying circuit and a predetermined time thereafter.