# Why is one of the transistors in ROM sense amplifier twice the width of the one opposite of him? 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?

• 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. – 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