# Homework 9 - Aidan Sharpe

## Problem 1
Find the best width and spacing to minimize the RC delay of a metal2 bus in a 180[nm] procecss if the pitch cannot exceed 960[nm]. Minimum width and spacing are 320[nm]. First, assume that neither adjacent bit is switching. How does your anwer change if the adjacent bits may be switching?

### Not Switching
When the bits are not switching, the speed is dependent on minimizing $R$. $R$ is smallest when $w$ is largest. If $s$ must be at least 320[nm] and $s+w$ must be no more than 960[nm], then the largest $w$ can be is 640[nm]. Therefore, the optimal pair is $s=320$[nm] and $w=640$[nm].

### Switching
When the bits are switching, the speed is dependent on minimizing the time constant $RC$. Estimating the value for $C$ from Figure 6.12, yields $s=480$[nm] and $w=480$[nm] to be optimal for minimizing the delay for switching bits.