Browse Prior Art Database

Dynamic RAM LSI With Wide Window for RAS Trailing Edge Timing

IP.com Disclosure Number: IPCOM000121206D
Original Publication Date: 1991-Aug-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 3 page(s) / 83K

Publishing Venue

IBM

Related People

Miyatake, H: AUTHOR [+2]

Abstract

The RAS (Row Address Strobe) signal low-to-high transition or trailing edge, which indicates the start of the RAS precharge phase in conventional Dynamic Random Access Memory (DRAM) LSIs, is gated by an internal signal which is driven to true state when the chip can go into the RAS precharge phase.

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Dynamic RAM LSI With Wide Window for RAS Trailing Edge Timing

      The RAS (Row Address Strobe) signal low-to-high
transition or trailing edge, which indicates the start of the RAS
precharge phase in conventional Dynamic Random Access Memory (DRAM)
LSIs, is gated by an internal signal which is driven to true state
when the chip can go into the RAS precharge phase.

      The timing when the chip can start the RAS precharge phase may
depend on each design of a DRAM, so the internal signal above can be
different from design to design.  For example, it is so formed that
it becomes "true" when the bit switch is turned off in ordinary read/
write (early write) operation or when the sense amplifier finishes
sensing in refresh operation and becomes "false" when the RAS signal
is activated.  Here, the bit switch is a pair of switch transistors
which control the connection between the bit line pair and the data
line pair and is selected by a column address.  Fig. 1 shows a
logical circuit diagram for the RAS signal gating, Fig. 2 shows a
timing chart for the internal RAS gating signal as defined above,
called RASPASS here, and Fig. 3 illustrates a logical circuit diagram
to generate the signal RASPASS.

      The advantage of this RAS trailing edge gating is that the user
may return the RAS signal to the inactive state any time after RAS
activation.  In other words, there is a very wide window for the RAS
signal trailing edge.  This is extremely beneficial especial...