Semiconductor memory device having function of generating write signal internally
First Claim
1. A semiconductor memory device receiving an external clock having a rising edge and a falling edge comprising:
- a memory cell array,a first latch circuit operatively connected to said memory cell array, for receiving a control signal designating one of a read cycle and a write cycle for said memory cell array, said first latch circuit latching said control signal in response to one of the rising edge and the falling edge of said external clock;
a second latch circuit operatively connected to said memory cell array, for receiving a write data, said second latch circuit latching said write data in response to another of the rising edge and the falling edge of said external clock; and
a write signal generating circuit operatively connected to said memory cell array and said first latch circuit, for feeding a write signal to said memory cell array when said control signal latched in said first latch circuit designates said write cycle.
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Accused Products
Abstract
A semiconductor memory device includes: a circuit for defining a cycle in response to a clock and a write enable signal and outputting a write control signal under a specific condition; a unit for inverting the clock to an inverted clock; a circuit for generating a write signal in response to the inverted clock when the write control signal is output; and a memory cell array in which a write access of data is carried out based on the write signal. Where a latch circuit is further provided which latches the write data and transmits the write data to the memory cell array in response to the clock or inverted clock and the write signal, an input terminal and an output terminal can be made common by making a latch timing of the write data different from that of the write enable signal, or the number of input terminals can be decreased by inputting the write data in a time sharing mode. This results in a decrease in scale of the whole circuit as a device. Also, by latching the write enable signal at a change in level of the clock and controlling a generation of the write signal or a prohibition of the generation at a reverse change in level thereof based on a control signal, a write operation can be cancelled, when necessary, with respect to a cell even if an address access to the cell is carried out.
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Citations
22 Claims
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1. A semiconductor memory device receiving an external clock having a rising edge and a falling edge comprising:
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a memory cell array, a first latch circuit operatively connected to said memory cell array, for receiving a control signal designating one of a read cycle and a write cycle for said memory cell array, said first latch circuit latching said control signal in response to one of the rising edge and the falling edge of said external clock; a second latch circuit operatively connected to said memory cell array, for receiving a write data, said second latch circuit latching said write data in response to another of the rising edge and the falling edge of said external clock; and a write signal generating circuit operatively connected to said memory cell array and said first latch circuit, for feeding a write signal to said memory cell array when said control signal latched in said first latch circuit designates said write cycle. - View Dependent Claims (2)
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3. A semiconductor memory device comprising:
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a cycle defining circuit for defining a read cycle and a write cycle in response to an external clock and an external write enable signal and outputting a read control signal or a write control signal based on a certain kind of defined cycle; means for inverting said clock to an inverted clock; a write signal generating circuit operatively connected to said cycle defining circuit, for generating a write signal in response to said inverted clock when said write control signal is output; a memory cell array in which a read access or write access of data is carried out based on said read control signal or said write signal; and a latch circuit operatively connected to said write signal generating circuit, for latching a write data and transmitting said write data to said memory cell array in response to said inverted clock and said write signal, whereby said write enable signal is latched at a change in level of said external clock in said write cycle and said write data is latched at a reverse change in level thereof. - View Dependent Claims (4, 5, 6, 7)
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8. A semiconductor memory device comprising:
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a cycle defining circuit for defining a cycle for carrying out a predetermined function in response to an external clock and an external write enable signal and outputting a write control signal in response to an external control signal in the defined cycle; means for inverting said clock to an inverted clock; a write signal generating circuit operatively connected to said cycle defining circuit, for generating a write signal in response to said inverted clock when said write control signal is output; and a memory cell array in which a write access of data is carried out based on said write signal, whereby said write enable signal is latched at a change in level of said external clock in said defined cycle, and a control of a generation of said write signal or a prohibition of said generation is carried out at a reverse change in level of said external clock in accordance with a logical level of said external control signal. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A semiconductor memory device comprising:
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a cycle defining circuit for defining a cycle for carrying out a predetermined function in response to an external clock and an external write enable signal, and outputting a write control signal based on a logical level of said write enable signal at the beginning of the defined cycle; means for inverting said clock to an inverted clock; a write signal generating circuit operatively connected to said cycle defining circuit, for generating a write signal in response to said inverted clock when said write control signal is output; a memory cell array in which a write access of data is carried out based on said write signal; and a latch circuit operatively connected to said write signal generating circuit, for latching a write data in response to either said external clock or said inverted clock and transmitting said write data to said memory cell array in response to said write signal, said write data being composed of a plurality of data and input in a time sharing mode, whereby a first half of said plurality of data is latched at a change in level of said external clock in said defined cycle and a second half thereof is latched at a reverse change in level thereof, and said plurality of data are simultaneously written in said memory cell array. - View Dependent Claims (20, 21, 22)
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Specification