Memory having selectable output strength
First Claim
1. An output buffer circuit having an input node adapted to receive an input signal and an output node adapted to provide an output signal, comprising:
- means for producing an output signal in response to a received input signal from a memory cell, the means for producing further comprising;
first current control means for providing current to or from the output node in response to the received input signal; and
second current control means for providing current to or from the output node in response to the received input signal, the first and second current control means being connected or connectable in parallel between the input node and output node; and
means for selectably controlling current flow through the means for producing to thereby control and/or select the output signal, the means for selectably controlling further comprising means for operably connecting the first and/or second current control means to the input and output nodes in response to a control signal to enable the operably connected current control means to provide current to the output node.
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Accused Products
Abstract
An output buffer circuit of a semiconductor memory device can produce multiple output buffer drive strengths. An electronic system including a memory device in which such an output buffer circuit is implemented can include a mechanism for enabling the output buffer drive strength to be easily selected by a user of the memory device (such as an assembler of an electronic system including the memory device) from the multiple possible drive strengths. The invention thus enables a memory device to be easily configured to have an output buffer drive strength that is compatible with a wide variety of electrical loads to be driven by the output buffers of the memory device. Since the output buffer circuit of the invention allows the output buffer drive strength to be more closely tailored to the electrical load being driven, signal reflections, voltage overshoot and undershoot, and timing problems that can result from mismatch between the output buffer drive strength and the associated electrical load can be reduced.
74 Citations
10 Claims
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1. An output buffer circuit having an input node adapted to receive an input signal and an output node adapted to provide an output signal, comprising:
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means for producing an output signal in response to a received input signal from a memory cell, the means for producing further comprising; first current control means for providing current to or from the output node in response to the received input signal; and second current control means for providing current to or from the output node in response to the received input signal, the first and second current control means being connected or connectable in parallel between the input node and output node; and means for selectably controlling current flow through the means for producing to thereby control and/or select the output signal, the means for selectably controlling further comprising means for operably connecting the first and/or second current control means to the input and output nodes in response to a control signal to enable the operably connected current control means to provide current to the output node. - View Dependent Claims (2, 3, 4)
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5. A system for selectably controlling the drive strength of an output buffer, comprising:
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a memory cell; an output buffer circuit adapted to receive an input signal from the memory cell and to provide an output signal, comprising; means for producing the output signal in response to the received input signal; and means for selectably controlling the current flow through the means for producing the output signal; and means for operating the means for selectably controlling in accordance with a control signal. - View Dependent Claims (6, 7, 8, 9, 10)
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Specification