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US 2003/0197546 A1Published application
Negative voltage generator for a semiconductor memory device
AssigneeSamsung Electronics Co., Ltd.
InventorsJae-Yoon Sim, Jei-Hwan Yoo
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AssigneeSamsung Electronics Co., Ltd.
InventorsJae-Yoon Sim, Jei-Hwan Yoo
Estimating the term…
A negative voltage generator is controlled responsive to a word line precharge signal. Voltage fluctuations in a negatively biased word line scheme are reduced by using a kicker circuit to provide a predetermined amount of negative charge to shut off a word line during a precharge operation. The negative voltage generator includes first and second negative charge pumps. The second charge pump is activated responsive to the word line precharge signal. A negative voltage regulator can be used to regulate a negative voltage signal. A level shifter uses two voltage dividers and a differential amplifier to reduce response time, output ripple, and sensitivity to process and temperature variations. A negative voltage regulator cancels ripple from a charge pump to provide a stable negative bias voltage and reduce the amount of charge needed to precharge a word line.
A negative voltage level detector for a semiconductor device comprising:
A negative voltage level detector for a semiconductor device comprising:
A negative voltage level detector for a semiconductor device comprising:
A method for detecting a negative voltage in a semiconductor device comprising:
A negative voltage regulator for a semiconductor device comprising:
A negative voltage regulator according to claim 32:
A negative voltage regulator for a semiconductor device comprising:
A negative voltage regulator for a semiconductor device comprising:
A method for generating a first negative voltage in a semiconductor device comprising:
Dependencies are inferred from the claim text.
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Using resistors or capacitors, e.g. potential divider: using capacitors charged and discharged alternately by semiconductor devices with control…
Power supply arrangements , e.g. power down, chip selection or deselection, layout of wirings or power grids, or multiple supply levels: voltage…
Auxiliary circuits, e.g. for writing into memory: power supply circuits
Using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps: adapted to generate a…
Term end not estimated
1. Field of the Invention
The present invention relates generally to semiconductor memory devices, and more particularly, to a negative voltage generator for a semiconductor memory device.
2. Description of the Related Art
FIG. 1 is a diagram of a prior art negative voltage generator.
FIG. 2 is a schematic diagram of a prior art level detector.
FIG. 3 illustrates the operation of a prior art negative voltage generator and level detector.
FIG. 4 is a diagram of an embodiment of a negative voltage generator in accordance with the present invention. The embodiment of FIG. 4 includes an oscillator 10, a first negative charge pump 20 having an output Vbb, and a level detector 30 arranged as in the prior art. However, the embodiment of FIG. 4 further includes a second negative charge pump 50 having an output coupled to the output of the first negative charge pump 20, either through a Vnn generator 40 as shown in FIG. 4, or through a direct connection as shown in FIGS. 5 and 6, or through any other suitable arrangement. The second negative charge pump 50 (also referred to as a “kicker”) is activated and supplies additional negative charge for shutting off a word line responsive to a precharge command or signal. The second negative charge pump is preferably designed to provide an accurately pre-determined amount of negative charge. Thus, by providing most of the precharge current required to shut off a word line, the second charge pump dramatically reduces voltage fluctuations on the negative voltage supply.
In a preferred embodiment, the second charge pump is constructed essentially the same as the first charge pump, but it is activated responsive to a precharge command or signal. The capacitor in the second charge pump is preferably sized to discharge just the right amount of charge from a word line during a precharge operation.
Since most semiconductor memory devices operate from positive power supplies that are referenced to a power supply ground, a back bias scheme is described in terms of a negative voltage. However, as used herein, negative is understood to mean simply the reverse polarity from that applied to a word line during an access operation.