Equation 5 · Part 3 · When the Substrate Became the Product

Symbol c_w

E_b \;\approx\; \tfrac{1}{2}\left(C_{\mathrm{fix}} + c_w \ell\right) V_{\mathrm{sw}}^{2},

c_w

What this part means

capacitance per unit length of the conductor.

Its job in the formula

$c_w$ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Full expressionSymbol c_wArticle meaning

Where the article explains it

where $C_{\mathrm{fix}}$ collects driver, receiver, bump and pad capacitance, $c_w$ is capacitance per unit length of the conductor, $\ell$ is the reach, and $V_{\mathrm{sw}}$ is the signalling swing.

The passage around this formula

…is a driven capacitive wire, and the energy spent per bit is set by the capacitance that must be charged and discharged: $E_b \;\approx\; \tfrac{1}{2}\left(C_{\mathrm{fix}} + c_w \ell\right) V_{\mathrm{sw}}^{2}$ . where $C_{\mathrm{fix}}$ collects driver, receiver, bump and pad capacitance, $c_w$ is capacitance per unit length of the conductor, $\ell$ is the reach, and $V_{\mathrm{sw}}$ is the signalling swing. Two assumptions are doing the work and both deserve stating. First, this treats the link as a lumped capacitance rather than a transmission line — reasonable for a few millimetres of…

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →

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Sources cited in the article section

[5] Bunch of Wires PHY Specification ↗

These citations provide research context; check each source for the exact claim it supports.