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Virtual Silicon Technology, Inc
1200 Crossman Ave #200
Sunnyvale, CA 94089-1116
Tel 408-548-2700
Fax 408-548-2750
 
Data Confidential and Subject to Change. Copyright 2001 Virtual Silicon Technology.
All rights reserved.
UMCL18U420T2_1.3
Wed Apr 9 15:49:34 MEST 2003
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Product Datasheet
eSi-RAM/2PTM
Two-Port Register File SRAM
128 Words 16 Bits per word

Functional Description

The two-port register file (Table 1) generated by the VST Two Port Register File compiler is a completely static memory device. The two-port register file has an address port for read and an independent address port for write (Fig.1, Table 2). The independent read and write cycles are timed with respect to their own clocks.

During a read cycle (Table 3), the output bus values are held if read enable is not asserted. The read enable feature is used to save RAM power without the need for external gating.

During a write cycle WEN, WADR, and DI are sampled at the rising edge of write clock (WCK). See Table 4.

Simultaneous read and write to different memory locations has no special timing restrictions. It is possible to perform a simultaneous read and write operation to the same address in one cycle. For this, the time between WCK and RCK must be Twckrck (Fig.2). If Twckrck is violated, there is a possibility that the Read data will be corrupted, but the Write cycle will complete properly.

The optional test pins are not included in this instance of the RAM.

Table 1: Configuration

ConfigurationValue
Compiler Two Port Register File
Process L180
Foundry umc
Size (microns) 134.52 by 445.52
Words 128
Bits 16
Mux 1
Power Bus o
Frequency 120
Power (uW/MHz) 33.61

The maximum power number given in the table above is for Fast process at 1.98 Volts and 0 Degrees C junction temperature.

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pin diagram
Table 2: Pin Description
eSi-RAM/2P
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Two Port
Register File SRAM
128 Words 16 Bits
 
Data Confidential and Subject to Change Copyright 2001 Virtual Silicon Technology All rights reserved.
UMCL18U420T2_1.3
Wed Apr 9 15:49:34 MEST 2003
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Name Type Description
RCKIRead clock.
RADR[6:0]IRead address bits, latched on rising RCK
WCKIWrite clock.
WADR[6:0]IWrite address bits, latched on rising WCK
DI[15:0]IData In bits, latched on rising WCK
WENIWrite Enable, Active Low, latched on rising WCK
RENIRead Enable, Active Low, latched on rising RCK
DOUT[15:0]OData out

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Table 3: Read Timing for Normal Operation

read timing waveforms

eSi-RAM/2P
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Two Port
Register File SRAM
128 Words 16 Bits
 
Data Confidential and Subject to Change Copyright 2001 Virtual Silicon Technology All rights reserved.
UMCL18U420T2_1.3
Wed Apr 9 15:49:34 MEST 2003
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Name Descrition Min Typ Max
TrcycClock cycle time2.59--
ThrckClock high time0.77--
TlrckClock low time0.77--
TsrenRead enable setup time0.11--
ThrenRead enable hold time0.00--
TsradrAddress setup time0.12--
ThradrAddress hold time0.00--
TpdoutClock to DOUT0.96-2.35
All times listed in nanoseconds. Timing values are given for these conditions: Max: Slow 1.62V 125 Deg, Typ: 1.8V 25 Deg, Min: Fast 1.98V 0 Deg. Output load 0.01pf, Input slews 0.04ns

This RAM has no test pins; all timing will be in normal mode.. Data stored in memory will appear at the output pins after Tpdout. Note that the DOUT pins will always be driven by the RAM, there is no tri-state.

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Table 4: Write Timing for Normal Operation

write timing waveforms

eSi-RAM/2P
wafer
Two Port
Register File SRAM
128 Words 16 Bits
 
Data Confidential and Subject to Change Copyright 2001 Virtual Silicon Technology All rights reserved.
UMCL18U420T2_1.3
Wed Apr 9 15:49:34 MEST 2003
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Name Descrition Min Typ Max
TwcycClock cycle time2.59--
ThwckClock high time0.77--
TlwckClock low time0.77--
TswadrAddress setup time0.04--
ThwadrAddress hold time0.03--
TswenWrite enable setup time0.07--
ThwenWrite enable hold time0.04--
TsdiData in setup time0.01--
ThdiData in hold time0.05--
All times listed in nanoseconds. Timing values are given for these conditions: Max: Slow 1.62V 125 Deg, Typ: 1.8V 25 Deg, Min: Fast 1.98V 0 Deg. Output load 0.01pf, Input slews 0.04ns

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Figure 2: Simultaneous Read and Write in one cycle (To the same address.)

clock to clock timing

eSi-RAM/2P
wafer
Two Port
Register File SRAM
128 Words 16 Bits
 
Data Confidential and Subject to Change Copyright 2001 Virtual Silicon Technology All rights reserved.
UMCL18U420T2_1.3
Wed Apr 9 15:49:34 MEST 2003
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Name Descrition Min Typ Max
TwckrckClock to clock separation1.29--
All times listed in nanoseconds. Timing values are given for these conditions: Max: Slow 1.62V 125 Deg, Typ: 1.8V 25 Deg, Min: Fast 1.98V 0 Deg. Output load 0.01pf, Input slews 0.04ns

Table 5: Input Capacitance

NameInput Cap (pf)
RCK 0.091
RADR 0.005
WCK 0.036
WADR 0.004
DI 0.009
WEN 0.004
REN 0.005
DOUT 0.016

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