Semiconductor memory device

• US 6,317,377 B1
• Filed: 04/11/2000
• Issued: 11/13/2001
• Est. Priority Date: 04/12/1999
• Status: Expired due to Term

• Current Assignee: Longitude Licensing Limited (Vector Capital Corporation)
• Original Assignee: NEC Corporation
• Inventors: Kobayashi, Shotaro
• Primary Examiner(s): Fears, Terrell W.
• Application Number:
  US09/546,915
• Time in Patent Office: 581 Days
• Field of Search: 365/51, 365/205, 365/231, 365/63, 365/220
• US Class Current: 365/220
• CPC Class Codes: G11C 7/1006 Data managing, e.g. manipulating data before writing or reading out, data bus switches or control circuits therefor

Abstract

The purpose of the present invention is to provide a semiconductor memory device which is capable of suppressing an increase in chip surface area and in power consumption resulting from peripheral circuitry even when the capacity thereof becomes large, and which, moreover, does not experience discrepancies in clock skew and the like between I/Os, and which is capable of high speed operation. 4-bit parallel data comprising a 0th through 3rd bit are exchanged simultaneously between memory cell arrays with respect to each I/O pin in DQ0-DQ7. Data of the 0th bit through 3rd bit are inputted and outputted with the exterior in that order via input/output interface circuit 5-1. At data load signal LOAD, flip flop groups 12-0 through 12-3 incorporate the 0th through 3rd bit data corresponding to 8 I/O pins. It is necessary to initially read out the 0th bit parallel data to the exterior, so that flip flop group 12-0 is disposed in closest proximity to the input/output interface circuit 5-1. The 8 bits are shifted together from flip flop group 12-3 to flip flop group 12-0 synchronously with clock signal CLOCK, and the 0th through 3rd bit data are outputted.

Claims

1. A semiconductor memory device having a plurality of input/output pads for receiving and outputting serial data, said memory device comprising:

a plurality of memory cell arrays which store and transfer data in a parallel format;

at least one serial-to-parallel converter/parallel-to-serial converter combination, wherein said serial-to-parallel converter converts said serial input data into said parallel format for transfer internal to said memory device and said parallel-to-serial converter converts said internal parallel data into serial format as output data from said memory device, and

a temporary storage unit integral to each said serial-to-parallel converter/parallel-to-serial converter combination, said temporary storage unit comprising a plurality of flipflops to store data in parallel format,

wherein each said serial-to-parallel converter/parallel-to-serial converter combination and integral temporary storage unit serve at least two said memory cell arrays that are adjacent, and

wherein said plurality of flipflops in said temporary storage unit are disposed in position such that said flipflops storing data which are initially outputted to the exterior are positioned in closest proximity to said input/output pads.

2. A semiconductor memory device in accordance with claim 1, wherein those of said flipflops storing data simultaneously exchanged with the exterior are disposed together with respect to all said input/output pads.

3. A semiconductor memory device in accordance with claim 1, wherein a control signal for controlling conversion operations by said serial-to-parallel converter/parallel-to-serial converter is supplied from a side of those said flipflops disposed in closest proximity to said input/output pads.

4. A semiconductor memory device in accordance with claim 1, wherein said serial-to-parallel converter/parallel-to-serial converter conducts conversion between said parallel data and said serial data by shifting data stored in said plurality of flipflops in accordance with a clock signal having a predetermined frequency, and

a direction in which said clock signal is supplied in order to said flipflops is opposite to a direction in which data stored in said flipflops are shifted.

5. A semiconductor memory device in accordance with claim 1, wherein said serial-to-parallel converter/parallel-to-serial converter is provided with a signal for selecting a memory cell array from among said adjacent memory cell arrays to conduct exchange of said parallel data.

6. A semiconductor memory device in accordance with claim 1, wherein said plurality of flipflops comprise shift registers.

7. A semiconductor memory device in accordance with claim 1, wherein said plurality of flipflops comprise a first shift means, which shifts said parallel data read out from said memory arrays and outputs said serial data in succession, and a second shift means, which conducts shifting, while successively incorporating said serial data supplied through said input/output pads and converts these to said parallel data;

and

said first shift means and said second shift means are disposed so that a shift direction of said first shift means and a shift direction of said second shift means are identical.

8. A semiconductor memory device in accordance with claim 7, wherein said first shift means and said second shift means comprise identical shift registers, and wherein the conversion operation from said parallel data to said serial data and the conversion operation from said serial data to said parallel data are conducted in a time-divided fashion.

9. A semiconductor memory device according to claim 1, wherein said input/output pads are disposed in such a manner as to be gathered at a central portion of a package and wherein said semiconductor memory device is sealed.