Hybrid Memory Cell for Two Port Rams
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
A static latch used in a random-access memory (RAM) macro may have the configuration shown in Fig. 1. This cell can be used in a two-port RAM and can easily interface with logic. For larger RAM macros further optimization is desirable. A hybrid two-port RAM cell is shown in Fig. 2. The advantages of this cell are: (1) retains the two-port capability and easy interface to logic; (2) less devices and wirings - smaller silicon area; (3) avoids the potential problems of direct base coupling; (4) potentially faster; and (5) bit select is possible for both write and read. The operation of this hybrid cell is illustrated in Fig. 3. Write is by emitter coupling, and read is by Schottky coupling. Some simplistic TTL peripherals are assumed which accept the regular logic levels.