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62 lines
3.2 KiB
Markdown
62 lines
3.2 KiB
Markdown
USEFUL CONSTANTS
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A list of some basic equations and constants I have found useful in my life as a chip and board designer.
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## Basic Laws
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| Rule | Value |
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|------------------------------------|---------------------------------------|
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| Speed of light | c = 299,792,458 m/s (~3.00x10^8 m/s) |
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| Vacuum permitivity | eps0 = 8.854187817 x 10-12 F/m |
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| Vacuum permeability | u0 = 4pi x 10-7 H / m or (V*s/A*m) |
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| Time of Flight (air) | 3.35 ps/mm |
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| Capacitance (parallel plate) | C = k * eps0 * Area / d |
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| Inductance (wire/ground plan) | L = (u/2pi) * ln ( 4 * h / d) |
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| Capacitor current | I = C * dV / dt |
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| Inductor voltage | V = L * dI / dt |
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| Resistor voltage | V = I * R |
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| Charge on capacitor | Q = C * V |
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| Power | P = I * V |
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| Dynaminc power for capacitive load | P = Freq * Cap * VDD^2 |
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| Energy | E = P * t |
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## Board Design
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| Rule | Value |
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|------------------------------------|---------------------------------------|
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| Lumped system rule of thumb (mm) | length < 1/6*Rise_time/time_of_flight |
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| Time of Flight (FR4-inner layer) | 7.09 ps/mm |
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## Chip Design
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| Rule | Value |
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|-----------------------------------|---------------------------------------|
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| De Morgan's Law |~(A AND B)=~A OR ~B,~(A OR B)=~A AND ~B|
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| RC delay | (0.35) * res/um * cap/um * L(um)^2 |
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| Relative permitivity (SiO2) | 3.9 |
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| Relative permitivity (Si) | 11.68 |
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| Line capacitance/mm (max density) | (highly variable!) |
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| Line resistance/mm (fat layer) | (copper, highly variable!) |
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## Interconnects
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| Rule | Value |
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|-------------------------------------|---------------------------------------|
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| Chip wire pitch | ~0.1um |
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| 2.5D wire pitch | 4um |
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| Wirebond pitch | 30um |
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| 2.5D Bump pitch | 45um |
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| Flip-chip pitch | 170um |
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| BGA pitch (advanced) | 400um |
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| BGA pitch (standard) | 1000um |
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| Hobby "solderable" connector | 2540um |
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| Ethernet connector | ~10,000um |
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