Patent Document

This application is a division of U.S. patent application Ser. No. 11/645,599 filed on Dec. 27, 2006 now U.S. Pat. No. 7,687,924, which claims priority of Korean patent application number 10-2006-0033049 filed on Apr. 12, 2006. The disclosure of each of the foregoing applications is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a semiconductor memory device, and more particularly, to a multi-port memory device having a serial input/output interface. 
     DESCRIPTION OF RELATED ART 
     A conventional dynamic random access memory (DRAM) operates at a relatively lower speed than a chipset connected to an external device. The DRAM operates at a low frequency and forms a data input/output (I/O) path connected in parallel to an interface that is to be connected to an external device. An operating speed of the DRAM is synchronized with that of the chipset in order to increase the entire data transfer rate. However, as faster processing speed is increasingly required, parallel data I/O operation has been limited. Thus, a DRAM using a high-speed serial I/O interface has become necessary. 
     As a bottleneck phenomenon can occur in a memory system when a single I/O interface is used, it is unreasonable to use a bandwidth that is much smaller than a maximum bandwidth of a memory core. To solve these problems, there is an increasing demand for a memory device that has a plurality of I/O interfaces, i.e., multi-ports, for the purpose of multiple access. It is expected that a memory device having a serial I/O interface and multi-port will be used as a buffer memory of a display device, for example, HD-TV, LCD, etc. 
       FIG. 1  is a diagram of a package ball out configuration of a ball grid array (BGA) packaging in a conventional 60-ball DDR2 DRAM. 
     In a single-port memory device having a parallel interface, only a DRAM part operating at a low speed is packaged. Thus, power used in the DRAM is supplied to balls. 
     However, if the package ball out configuration of  FIG. 1  is applied to a multi-port memory device having a serial I/O interface, package efficiency is degraded. 
     The multi-port memory device having the serial I/O interface has transmission pins and reception pins as many as the ports. The transmission pins and the reception pins have a differential structure for data I/O operation. The operation stability can be secured when package loads of the transmission pins and the reception pins (balls) are equal to one another. In the package ball out configuration of  FIG. 1 , however, the parallel I/O interface (DQ pin) cannot be replaced with the serial I/O interface. Thus, the package loads of the transmission pins and the reception pins (balls) for the serial I/O interface are not considered. 
     In addition, because the high-speed serial I/O interface part and the low-speed DRAM part operate together, the unstable power voltage level caused by the abrupt power consumption at one side degrades the operation stability of the other side. For this reason, most of the multi-port memory devices having the serial I/O interface include separate power supplies for the serial I/O interface part and the DRAM part. If the power supplies are separately provided for the different use, it is difficult to configure a power layer that manages the power supply. When two power supplies have different levels, the above-described problems become more serious. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a multi-port memory device having a serial I/O interface, which is capable of providing an efficient package ball out configuration for a structure in which a DRAM part operating at a low frequency and a serial I/O interface part operating at a high frequency coexist. 
     In accordance with an aspect of the present invention, there is provided a multi-port memory device having a serial I/O interface, including: a first package ball out region in which a plurality of balls for a serial I/O interface part are arranged; and a second package ball out region in which a plurality of balls for a DRAM part are arranged. 
     In accordance with another aspect of the present invention, there is provided a multi-port memory device having a serial I/O interface, including: a first package ball out region in which a plurality of balls for a serial I/O interface part and a clock part are arranged; and a second package ball out region in which a plurality of balls for a DRAM part are arranged. 
     In accordance with a further aspect of the present invention, there is provided a multi-port memory device having a serial I/O interface, including: a first package ball out region in which a plurality of balls for a serial I/O interface part are arranged; and a second package ball out region in which a plurality of balls for a DRAM part and a clock part are arranged. 
     When the multi-port memory device includes the high-speed serial I/O interface part and the low-speed DRAM part, the part for supplying power to the high-speed serial I/O interface part is independently separated from the part for supplying power to the low-speed DRAM part, thereby making it easy to configure the power layer in the package. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a diagram of a package ball out configuration of a BGA packaging in a conventional 60-ball DDR2 DRAM; 
         FIG. 2  is a diagram of a package ball out configuration of a multi-port memory device having a serial I/O interface in accordance with a first embodiment of the present invention; and 
         FIG. 3  is a diagram of a package ball out configuration of a multi-port memory device having a serial I/O interface in accordance with a second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A multi-port memory device in accordance with exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 2  is a diagram of a package ball out configuration of a multi-port memory device having a serial I/O interface in accordance with a first embodiment of the present invention. 
     The package ball out configuration in accordance with the first embodiment of the present invention includes a first package ball out region  100  and a second package ball out region  200 , which are arranged at the left and right sides of a vertical center line, respectively. 
     Balls  110  for a serial I/O interface part and balls  150  for a clock interface part are arranged in the first package ball out region  100 , and balls for a DRAM interface part are arranged in the second package ball out region  200 . 
     In the first package ball out region  100 , the balls  110  for the serial I/O interface part include serial data balls  111  and serial power/ground balls  112 . The serial data balls  111  are used for serial data communication TX 0 +/TX 0 −, RX 0 +/RX 0 −, TX 1 +/TX 1 −, RX 1 +/RX 1 −, TX 2 +/TX 2 −, RX 2 +/RX 2 −, TX 3 +/TX 3 − and RX 3 +/RX 3 −. The serial power/ground balls  112  are used to supply power voltage VDDQ and ground voltage VSSQ to the serial data balls  111 . 
     The balls  150  for the clock interface part include clock interface balls  151  and clock power/ground balls  152 . The clock interface balls  151  are used to transfer clock signals CK and /CK, and the clock power/ground balls  152  are used to supply power voltage VDDA and ground voltage VSSA to the clock interface balls  151 . 
     In the package ball out configuration of  FIG. 2 , the first package ball out region  100  having the power/ground balls VDDQ and VSSQ of the high-speed serial I/O interface is independently separated from the second package ball out region  200  having the power/ground balls VDD and VSS of the low-speed DRAM part. This makes it easy to configure the power layer of the package. 
     In addition, the serial data balls  111  are arranged in a differential structure (TX+/TX−, RX+/RX−) for data I/O operation. The data I/O parts of the serial I/O interface are separated into the transmit pins (TX+, TX−) and the receive pins (RX+, RX−) in each port. Therefore, the stability of the data I/O operation can be secured. That is, because TX 0 +/TX 0 −, RX 0 +/RX 0 −, TX 1 +/TX 1 −, RX 1 +/RX 1 −, TX 2 +/TX 2 −, RX 2 +/RX 2 −, TX 3 +/TX 3 − and RX 3 +/RX 3 − are separately arranged, the loads of the I/O package ball out can be equal to one another. 
       FIG. 3  illustrates a package ball out configuration of a multi-port memory device having a serial I/O interface in accordance with a second embodiment of the present invention. 
     The package ball out configuration in accordance with the second embodiment of the present invention includes a first package ball out region  300  and a second package ball out region  400 , which are arranged at the left and right sides of a vertical center line, respectively. 
     Balls  310  for a serial I/O interface are arranged in the first package ball out region  300 . Balls  450  for a clock interface part and balls  410  for a DRAM interface part are arranged in the second package ball out region  400 . Since the package ball out configuration of  FIG. 3  is different from that of  FIG. 2  only in terms of the arrangement of the balls  450  for the clock interface part, its detailed description will be omitted for conciseness. 
     As described above, the power layer of the package can be easily configured by separately arranging the high-speed serial I/O interface part and the low-speed DRAM part. Moreover, the data I/O configuration of the independent serial I/O interface part is separately arranged, thereby securing the data stability. 
     The present application contains subject matter related to Korean patent application No. 2006-33049, filed in the Korean Intellectual Property Office on Apr. 12, 2006, the entire contents of which are incorporated herein by reference. 
     While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.

Technology Category: 5