Digital ICs/DSP: Registered DDR SDRAM Module Packs 1 Gbit In Small Surroundings

Organized as 16 Mwords by 72 bits, a novel registered double-data-rate (DDR) SDRAM module comes in speed grades of 200, 225, or 250 MHz. The W3E16M72SR-XBM multichip solution comes in a 32- by 25-mm, 219-contact plastic ball grid array. In the same footprint, the company will offer a 32-Mword by 72-bit version. Both feature bidirectional data strobes (DQS) transmitted per byte; DQS edge-aligned with data for Reads, and center-aligned with data for Writes. Internally, the memory module uses a pipelined DDR architecture with two data accesses per clock cycle and four internal banks for concurrent operation. In lots of 1000, the multichip module costs less than $200 each. Production lead time is six to eight weeks.