Internal voltage generator for semiconductor memory device

Abstract

An internal voltage generator capable of reducing the variation width in the level of an internal voltage VPP, by performing charge pumping only a predetermined number of times in a period where an oscillator driving signal is at a logic HIGH level, and then stopping the charge pumping operation. The oscillator controller generates an oscillation control signal for stopping an oscillation operation of a ring oscillator by using an output signal of a level detector and an output signal of the ring oscillator. The ring oscillator does not generate an oscillation signal at a predetermined time point where an output signal of the level detector is at a HIGH level in response to the oscillation control signal. The charge pump circuit generates an internal voltage by performing a charge pumping operation only predetermined times in response to the oscillation signal, and then stopping the charge pumping operation.

Description

BACKGROUND [0001] 1. Technical Field [0002] An internal voltage generator for generating a high voltage VPP or a substrate voltage in a semiconductor memory device is shown and described. [0003] 2. Description of the Related Art [0004] As semiconductor memory devices become faster and lower in power usage, internal operation becomes very sensitive to noise. Semiconductor memory, particularly DRAM devices, usually include an internal voltage generator for generating an internal voltage of a predetermined level for the internal operation in addition to an external input voltage. An internal voltage generator can generate a voltage higher than an external high voltage, i.e., a high voltage VPP, or a voltage lower than an external low voltage (usually, ground voltage), i.e., a back bias voltage or a substrate voltage. An internal voltage generator generates an internal voltage of a predetermined level by employing a charge pumping mode. [0005]FIG. 1 is a block diagram illustrating the c...

AI Technical Summary

Benefits of technology

[0012] Accordingly, an internal voltage generator is disclosed which is capable of reducing the variation width in the level of an internal voltage VPP by performing charge pumping only a predetermined number of times even when an oscillator driving signal is at a logic HIGH level, and then stopping the charge pumping operation.

Problems solved by technology

As semiconductor memory devices become faster and lower in power usage, internal operation becomes very sensitive to noise.

In this case, there is a problem in that the voltage level of the internal voltage VPP undesirably increases higher than the target level because the charge pumping operation continues.

Accordingly, there is a problem in that the variation width in the level of the internal voltage VPP is greater.

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