Tetsu Udagawa

A 23-ns 1-Mb BiCMOS DRAM

A 1-Mb BiCMOS DRAM having a 23-ns access time is described. The DRAM uses a direct sensing technique and a nonaddress-multiplexing configuration. This technique combines the NMOS differential circuit on each pair of data lines with a common highly sensitive bipolar circuit. The resulting chip has been verified to have high-speed characteristics while maintaining a wide operating margin and a relatively small chip size of 62.2 mm/sup 2/, in spite of a 1.3- mu m lithography level. >

A 23ns 1Mbit BiCMOS DRAM

I -_JLd Lioduction Bit density oi DRAMs has continued to be improved by a factor of four times every three years. In contrast with these remarkable improvemenls in bit densitv, improvements in access and cycle times of DRAMs available in the market are insufficient for higher performance applications. For improving DRAM speed with reasonable process complexity, a 1.3ßm 1Mbit BiCMOS DRAM has been reported (I). However, performance of the previous DRAM is insufficient, although BiCMOS technology was verified as having advantages for improving speed, power dissipation and soft error rate (2)(3). In this paper, a 23ns 1.3 fi m 1Mbit BiCMOS DRAM, suitable for imss production, is described. First, high-speed sensing circuit techniques combined with a non