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// SAME Analog Modular Ecosystem
//
// / SPDX-FileCopyrightText: 2026 Denis Chevalier <perso@denischevalier.fr>
// / SPDX-License-Identifier: CC-BY-SA-4.0
// / SPDX-License-Identifier: CERN-OHL-S-2.0+
// / SPDX-License-Identifier: GPL-3.0-or-later
//
// The prose, explanatory text, rendered figures, tables, and mathematical
// content of this specification are licensed under CC BY-SA 4.0. If a later
// version of CC BY-SA is published, the author grants permission to distribute
// this work under that later version as well.
//
// Hardware designs contained herein (schematics, PCB layouts, mechanical
// drawings, and CAD models) are licensed under CERN-OHL-S-2.0+.
//
// All executable code, helper libraries (`lib/*`), metrology assertions, and
// embedded verification scripts throughout the source documents are licensed
// under the GNU General Public License v3.0 or later (GPL-3.0-or-later).
#import "../lib/unify.typ": qty, unit
#import "@preview/cetz:0.5.2"
#import "@preview/cetz-plot:0.1.4": plot
#figure(
cetz.canvas({
import cetz.draw: *
plot.plot(
size: (12, 6),
x-mode: "log",
x-label: [Frequency $f$ ($unit("Hz")$)],
y-label: [Coupled Voltage $V_"coupled"$ ($unit("mV")$)],
x-min: 10,
x-max: 100000,
y-min: 0.001,
y-max: 65,
x-grid: "minor",
y-grid: "minor",
{
// 20 kHz System Bandwidth limit vertical reference line
plot.add(
((20000, 0.001), (20000, 100)),
style: (
stroke: (paint: luma(120), thickness: 0.8pt, dash: "dashed"),
),
label: none,
)
// Unshielded PCB trace: C_mutual = 1 pF, Z_victim = 10 kOhm
plot.add(
style: (stroke: (dash: "solid")),
label: [Unshielded trace \
($qty(1, "pF"), qty(10, "kilo ohm")$)],
domain: (10, 100000),
samples: 1000,
f => 2 * calc.pi * f * 1e-12 * 10000 * 10 * 1000, // in mV
)
// Low-impedance node: C_mutual = 1 pF, Z_victim = 1 kOhm
plot.add(
style: (stroke: (dash: "dashed")),
label: [Low-impedance node \
($qty(1, "pF"), qty(1, "kilo ohm")$)],
domain: (10, 100000),
samples: 1000,
f => 2 * calc.pi * f * 1e-12 * 1000 * 10 * 1000, // in mV
)
// Guard trace shielding: C_mutual = 0.05 pF, Z_victim = 10 kOhm
plot.add(
style: (stroke: (dash: "dotted")),
label: [Guard trace shielded \
($qty(0.05, "pF"), qty(10, "kilo ohm")$)],
domain: (10, 100000),
samples: 1000,
f => 2 * calc.pi * f * 0.05e-12 * 10000 * 10 * 1000, // in mV
)
},
)
}),
caption: [Capacitive crosstalk coupled voltage ($V_"coupled"$) vs. frequency across different PCB layout conditions, demonstrating the $qty(20, "decibel per decade")$ slope up to the $qty(20, "kHz")$ system bandwidth boundary],
) <figure-crosstalk-mathematical-model>
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