Memory Voltage Pumping Circuit for VBB Coupling 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 increased leakage current and 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
1Speed
If the pumping voltage VPP is raised to reach its target level quickly, then the voltage generation speed is improved, but the coupling characteristic impedes the negative voltage VBB from reaching its target level, causing increased leakage current
Solution Approach 1:
The patent divides the pumping voltage generation into multiple independent pumping units (first pumping unit, second pumping unit, third pumping unit) that can be controlled separately. This segmentation allows the circuit to raise VPP through staged pumping operations while managing the coupling effect on VBB, thereby reducing leakage current caused by simultaneous voltage transitions.
2Power
If multiple pumping units are used to generate voltages, then the voltage generation capability is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple pumping units with a shared oscillator and control logic into an integrated voltage generation circuit. The oscillator generates a single oscillating signal that is distributed to multiple pumping units, and the control unit manages all pumping operations centrally. This merging approach enables high voltage generation capability while minimizing the increase in circuit complexity through resource sharing.
3Object-generated harmful factors
If the negative voltage VBB reaches its target level slowly, then the coupling characteristic is avoided, but the current consumption increases due to prolonged leakage current
Solution Approach 1:
The patent employs a control unit that monitors the voltage levels of both VPP and VBB and adjusts the pumping operations accordingly. When VBB approaches its target level, the control unit modulates the pumping units to maintain the negative voltage, preventing the coupling characteristic from affecting VPP generation. This preliminary control action reduces leakage current and minimizes energy loss by avoiding prolonged voltage mismatches.
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.