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uTwo DIMM designs with Single PCB

IP.com Disclosure Number: IPCOM000130346D
Original Publication Date: 2005-Nov-25
Included in the Prior Art Database: 2005-Nov-25
Document File: 2 page(s) / 1M

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

Memory requirements of computers are increasing day by day. In order to get higher memory densities it is required to design new memory cards to accommodate more memory on DIMMs (Dual In-Line Memory Modules). For different separate designs the cost of producing and logistics is high. Therefore, it is proposed to use a special PCB (Printed Circuit Board) design to make two cards as a variation of a single PCB. A 4 Giga Byte Registered DIMM (Using 36 planar 1 Giga bit DRAMs) and a 8 Giga Byte Registered DIMM (Using 36 Stacked 2 Giga bit DRAMs) are made using a single PCB, which can be assembled during production/assembly line as a 2R (Rank) Module or 4R Module just by changing the BOM (Bill of material).The 4GByte Module is made as a 2Rank module and the 8Gbyte module is made as 4Rank module. The Control Signals, Lines and Nets are connected differently in 2Rank or 4Rank modules as shown in figure 1. The 2Rank Module has 2 CS (Chip Select), 2 CKE (Clock Enable) and 2 ODT (On Die Termination), whereas the 4Rank module has 4CS, 2CKE and 2ODT. The Implementation, an example of changing CS, is shown in figure 1 and 2:

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uTwo DIMM designs with Single PCB

Idea: Abdallah Bacha, DE-Munich; Simon Muff, DE-Munich, Ch. Siva Raghu Ram, DE-Munich;

Peter Fettich, DE-Munich

Memory requirements of computers are increasing day by day. In order to get higher memory densities it is required to design new memory cards to accommodate more memory on DIMMs (Dual In-Line Memory Modules). For different separate designs the cost of producing and logistics is high.

Therefore, it is proposed to use a special PCB (Printed Circuit Board) design to make two cards as a variation of a single PCB. A 4 Giga Byte Registered DIMM (Using 36 planar 1 Giga bit DRAMs) and a 8 Giga Byte Registered DIMM (Using 36 Stacked 2 Giga bit DRAMs) are made using a single PCB, which can be assembled during production/assembly line as a 2R (Rank) Module or 4R Module just by changing the BOM (Bill of material).The 4GByte Module is made as a 2Rank module and the 8Gbyte module is made as 4Rank module. The Control Signals, Lines and Nets are connected differently in 2Rank or 4Rank modules as shown in figure 1. The 2Rank Module has 2 CS (Chip Select), 2 CKE (Clock Enable) and 2 ODT (On Die Termination), whereas the 4Rank module has 4CS, 2CKE and 2ODT.

The Implementation, an example of changing CS, is shown in figure 1 and 2:

The positions of R401 and R402 are changed from 1-2 to 1-3. The values of R105-R107 are changed from 0Ω to 10Ω. The values of R405-R407 are changed from 0Ω to 10Ω Ohm and their position from 1-2 to 1-3...