What dominates the area and power in single-port SRAM and in dual-port SRAM?

[eexuke]

Dear experts,
Currently when I am comparing on-chip SRAM size (0.18um,UMC),I found a weird result:
Single-port SRAM:4k*16,area 0.38um^2,power 167 uW/MHz
Dual-port SRAM :4k*16,area 0.91um^2,power 79 uW/MHz/port
The dual-port SRAM has two separate ports which can be configured as two simultaneously read, two simultaneously write, and one read one write.

The question is:why the power consumption of dual-port SRAM is smaller even if its chip area is nearly 3 times than single-port?

What dominates the area and power in single-port SRAM and in dual-port SRAM?

Thanks in advance!

 

[svr]

Re: SRAM questions

Two port SRAM is smaller than dual port SRAM.
Two port SRAM is one port only for read and one port only for write.
Dual port SRAM provides two port for read or write.

Since it is Static Circuitry, the power consumption is largely dependent on the switching activity.

 

[quan228228]

Re: SRAM questions

The power has two types. one is dynamic power and static power. The SRAM power consumpation is depedent on reading and writing operation.
No reading and writing , no dynamic power.

I dont know how is the number you gave calculated.

/David

 

[irfansyah]

Re: SRAM questions

That's very interesting.

As far as i know, i'm not an SRAM expert, what affects the area of a RAM is the size of the memory itself. For the same technology, the dual port SRAM might have a memory capacity almost 3 times the single port one. But this also depends on what else is included in the circuit. Say, if long interconnect wires for external interfacing is also included, than another question arises: what sort of signaling does it use?

If the interconnect uses differential signaling, it will certainly consume at least twice the area, but it can be made more low power compared to the single-ended signaling by reducing the voltage swing significantly. I don't know if that's the case in your problem though.