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determining_pinout [2012/03/02 02:23] mcmaster |
determining_pinout [2013/10/20 10:59] (current) |
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| {{gallery>:mcmaster:pmos_nmos_sizes.jpg}} | {{gallery>:mcmaster:pmos_nmos_sizes.jpg}} | ||
| - | Notice that the right side is larger? This means that the right side is PMOS and the left side is NMOS. Since NMOS on the right likes to connect to ground (V-) and PMOS on the left likes to connect to power (V+) we have identified the power nets. This can then be traced as needed. | + | Notice that the left side is smaller than the right? This means that the left side is NMOS and the right side is PMOS. Since NMOS on the left likes to connect to ground (V-) and PMOS on the right likes to connect to power (V+) we have identified the power nets. This can then be traced as needed. |
| If the cells are matched size or its a specialized chip you might not have this luxury. In that case start looking for connections to ground rings. For example, in this chip power pins are very distinctive because the protection network is very different, it feeds directly to the power ring around the chip, and the input is a lot larger: | If the cells are matched size or its a specialized chip you might not have this luxury. In that case start looking for connections to ground rings. For example, in this chip power pins are very distinctive because the protection network is very different, it feeds directly to the power ring around the chip, and the input is a lot larger: | ||