Add more homework solutions.
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32
HW3.tex
32
HW3.tex
@@ -80,7 +80,7 @@ For all inverters, then, we get the following:
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\pagebreak
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\section*{Q4}
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First, to compute stage effort $\hat{f}$.
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First, to compute total effort $F$.
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\begin{equation*}
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\begin{aligned}
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@@ -92,29 +92,27 @@ First, to compute stage effort $\hat{f}$.
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\end{aligned}
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\end{equation*}
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Assuimng a $p_\text{invs}$ of 1, and thus $\rho = 3.59$, we get:
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Since we are using the same inverter as the one in Q3, we are
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once again using $p_\text{inv}=5$, and thus, have that $\rho=6.138$.
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From this, we can determine the ideal number of stages:
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\begin{equation*}
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\log_\rho F = 7.2 \approx 7
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\log_\rho F = 5.13 \approx 5
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\end{equation*}
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Since we currently have 3 stages, we should insert 4 inverters.
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It appears as though inserting inverters only at the end makes it
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too difficult for the first-stage NAND gate to drive the 3-branched
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NOR gates (we end up with an optimal size less than 1). Instead,
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I will insert two inverters right after the NAND2 gate, and two more
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inverters at the end. We can now compute gate sizes:
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Since we currently have 3 stages, we should insert 2 inverters.
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I will insert these at the end of the path in question. From
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there, we once again compute stage effort $\hat{f}$, and work
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backwards to determine the optimal sizes for all of the stages.
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\begin{equation*}
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\begin{aligned}
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\hat{f} &= \sqrt[7]{11111} \\
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\text{sz}_7 &= 1000/\hat{f}^1 = 264 \\
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\text{sz}_6 &= 1000/\hat{f}^2 = 69.8 \\
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\text{sz}_5 &= 1000/\hat{f}^3 * \left(\frac{5}{3}\right) = 30.8 \\
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\text{sz}_4 &= 1000/\hat{f}^4 * \left(\frac{5}{3}\right)\left(\frac{5}{3}\right) = 13.5 \\
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\text{sz}_3 &= 1000/\hat{f}^5 * \left(\frac{5}{3}\right)\left(\frac{5}{3}\right)3 = 10.7 \\
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\text{sz}_2 &= 1000/\hat{f}^6 * \left(\frac{5}{3}\right)\left(\frac{5}{3}\right)3 = 2.84 \\
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\text{sz}_1 &= 1000/\hat{f}^7 * \left(\frac{5}{3}\right)\left(\frac{5}{3}\right)3 = 1 \\
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\hat{f} &= \sqrt[5]{11111} \\
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\text{sz}_\text{inv1} &= 1000/\hat{f}^1 = 155 \\
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\text{sz}_\text{inv2} &= 1000/\hat{f}^2 = 24.1 \\
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\text{sz}_\text{nand3} &= 1000/\hat{f}^3 * \left(\frac{5}{3}\right) = 6.23 \\
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\text{sz}_\text{nor2} &= 1000/\hat{f}^4 * \left(\frac{5}{3}\right)\left(\frac{5}{3}\right) = 1.61 \\
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\text{sz}_\text{nand2} &= 1000/\hat{f}^5 * \left(\frac{5}{3}\right)\left(\frac{5}{3}\right)\left(\frac{4}{3}\right)3 = 1
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\end{aligned}
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\end{equation*}
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