Memory Voltage Pumping Circuit for VBB Leakage Suppression
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Solution Overview
Problem
In semiconductor memory apparatuses, the coupling characteristic between the drain and back bias terminal impedes the negative voltage VBB from reaching its target level, leading to leakage current and increased current consumption due to the pumping voltage VPP not reaching its target level in a timely manner.
Innovation Solution
A voltage generation circuit with multiple pumping units, a sensing unit, an oscillator, and a control unit that selectively outputs oscillator signals based on active, power-up, and mode register set signals to manage voltage levels and reduce leakage current by controlling the pumping operations of first, second standby, and active pumping units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the pumping voltage VPP is raised to the target level, then the transistor can operate properly, but the negative voltage VBB cannot reach its target level due to coupling characteristic, causing leakage current
Solution Approach 1:
The patent divides the voltage generation into separate pumping units (first pumping unit for VPP, second pumping unit for VBB) that can be independently controlled. This segmentation allows each voltage to be regulated separately, preventing the coupling effect from causing both voltages to fail to reach their target levels simultaneously.
Solution Approach 2:
The patent applies preliminary action by first generating the negative voltage VBB to its target level before raising the pumping voltage VPP to its target level. This sequence is controlled through sensing units that monitor voltage levels and control units that activate pumping units in a specific order, ensuring VBB is stabilized first to prevent leakage current.
2Loss of energy
If the negative voltage VBB is raised to the target level, then leakage current is reduced, but the pumping voltage VPP may not reach its target level timely
Solution Approach 1:
The patent implements preliminary action by prioritizing the generation of negative voltage VBB to its target level before activating the pumping voltage VPP. The control unit monitors voltage levels and activates the second pumping unit for VBB first, ensuring leakage current is minimized before the system fully operates, thereby reducing energy loss without excessive delay.
Solution Approach 2:
The patent uses periodic action through oscillating signals generated by oscillators in each pumping unit. These oscillating signals continuously pump charges to maintain voltage levels, allowing the system to efficiently reach and sustain target voltages through periodic charge transfer rather than continuous operation.
3Manufacturing precision
If multiple pumping units are used to generate voltages, then voltage level control is improved, but the device complexity increases
Solution Approach 1:
The patent segments the voltage generation function into multiple independent pumping units, each with its own sensing unit and control unit. This modular segmentation improves voltage level control precision for each voltage (VPP and VBB) while organizing the complexity into manageable, repeatable modules that can be independently optimized and maintained.
Solution Approach 2:
The patent applies universality by designing pumping units with similar structures that can perform multiple functions - each pumping unit can generate different voltages (VPP or VBB) depending on activation. The sensing units and control units also serve universal purposes of monitoring and regulating voltage levels, reducing the need for entirely separate control circuits for each voltage.
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
The solution effectively suppresses the coupling characteristic between the drain and back bias terminal, reducing leakage current and decreasing current consumption by ensuring the negative voltage VBB reaches its target level efficiently.
Implementation Method 1
a sensing unit configured to sense a voltage level of an output node and generate a pumping enable signal
Implementation Method 2
an oscillator configured to generate an oscillator signal in response to the pumping enable signal
Implementation Method 3
a first standby pumping unit configured to perform a pumping operation in response to the oscillator signal, and output a voltage generated by the pumping operation, to the output node
Data Source
AI summary
A voltage generation circuit of a semiconductor memory apparatus includes a plurality of pumping units configured to provide voltages to an output node; a sensing unit configured to sense a voltage level of the output node and generate a pumping enable signal; an oscillator configured to generate an oscillator signal in response to the pumping enable signal; and a control unit configured to selectively output the oscillator signal to the plurality of pumping units in response to an active signal, a power-up signal and a mode register set signal.