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The picture is of Sense Amp design of ROM component in which a 'dummy' bit line is used to imitate the current so that the proper information can be derived from the memory cell by comparing the currents.

I would like to know why does the right transistor have a width of 2Wx and the one on the left Wx?

  • \$\begingroup\$ A 2Wx transistor is exactly the same as placing two Wx transistors in parallel. Now, if we apply a voltage across a Wx transistor, a current would flow. How much current would flow when the same voltage is applied to a 2Wx transistor? It is unclear from the schematic why those current relation would be needed as the schematic is incomplete and unclear to me. \$\endgroup\$ – Bimpelrekkie Jan 12 '19 at 22:11

the one on the right sees two signals a "0" (\$I_0\$) and a "1" (\$I_1\$) the one on the left sees one signal \$I_m\$ a '0' or a 'i'

the compartor computes \$ I_m > ( I_0 + I_1 ) / 2 \$

To get the /2 it needs to be twice as wide on other side

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