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https://github.com/diodeinc/pcb.git
synced 2026-09-14 20:17:19 +08:00
Akhil Velagapudi
4413c9d4d9
* Hydrate V2 deps during migrate * Fix mixed hydrated package resolution * Simplify workspace discovery * Clean up workspace package discovery naming * Update stdlib formatting paths
45 lines
1.3 KiB
Plaintext
45 lines
1.3 KiB
Plaintext
* Crystal SPICE subcircuit
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* Butterworth-Van Dyke equivalent circuit model
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*
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* The crystal is modeled as:
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* - Series RLC branch (motional components): Lm, Cm, Rm
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* - Parallel capacitance: Cp (shunt/holder capacitance)
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*
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* Parameters:
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* FREQ - Resonant frequency in Hz
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* Lm - Motional inductance (default calculated from frequency)
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* Cm - Motional capacitance (default: 10fF typical for MHz crystals)
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* Rm - Motional resistance/ESR (default: 50 ohms)
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* Cp - Parallel/shunt capacitance (default: 3pF)
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*
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* Nodes:
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* 1 - Terminal 1 (XIN)
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* 2 - Terminal 2 (XOUT)
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* 2-pin crystal model
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.SUBCKT XTAL_2PIN 1 2 PARAMS: FREQ=10e6 Cm=10f Rm=50 Cp=3p
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* Calculate Lm from frequency: Lm = 1/(4*pi^2*f^2*Cm)
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.PARAM Lm={1/(4*3.14159*3.14159*FREQ*FREQ*Cm)}
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* Series RLC branch (motional components)
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Lmot 1 3 {Lm}
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Cmot 3 4 {Cm}
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Rmot 4 2 {Rm}
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* Parallel capacitance (holder/shunt capacitance)
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Cpar 1 2 {Cp}
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.ENDS XTAL_2PIN
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* 4-pin crystal model with grounded case
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.SUBCKT XTAL_4PIN 1 2 3 PARAMS: FREQ=10e6 Cm=10f Rm=50 Cp=3p Ccase=1p
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* Calculate Lm from frequency
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.PARAM Lm={1/(4*3.14159*3.14159*FREQ*FREQ*Cm)}
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* Series RLC branch (motional components)
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Lmot 1 4 {Lm}
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Cmot 4 5 {Cm}
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Rmot 5 2 {Rm}
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* Parallel capacitance
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Cpar 1 2 {Cp}
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* Case capacitances to ground (pin 3)
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Ccase1 1 3 {Ccase}
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Ccase2 2 3 {Ccase}
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.ENDS XTAL_4PIN
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