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Write-Through Function for Fast Data Access in Multi-port RAM

IP.com Disclosure Number: IPCOM000107675D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Singh, RP: AUTHOR [+2]

Abstract

Write-through access time is improved by precharging write and read bit lines, and by writing a 'one' in the decoded word line with the self- timed clock pulses in the first half of the clock cycle.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 96% of the total text.

Write-Through Function for Fast Data Access in Multi-port RAM

       Write-through access time is improved by precharging
write and read bit lines, and by writing a 'one' in the decoded word
line with the self- timed clock pulses in the first half of the clock
cycle.

      The figure shows a typical write-through path for multiport
SRAM.  Operation is as follows:  During the initial phase of the
clock cycle, the write and read word lines are selected.  The read
and write bit lines are precharged to VDD and a 'one' is written in
the selected cell.  The data output is also precharged to one.  In
the second half of the cycle, the write-through access of zero data
consists of delay from cell's data input port 'DI' to sense amp
output port 'DO'.  Word line and bit line addressing does not
contribute to write-through access time. The design of the
write-through circuits is skewed toward writing and reading a zero.
The timing is further enhanced by the sense amplifier device TX which
isolates capacitive Dot-ORed Read bitlines from the sense transistor
TP.  Sense amplifier input TP is precharged to VDD while read bit
lines are precharged to threshold below VDD.  Small voltage drop on
bit lines get amplified at the sense node which also reduces read
access time.

      To summarize, all decoding and precharging precedes data input.
Read and write access times are improved by precharging the sense amp
input and output.  Also, selected cells are preloaded with o...