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https://github.com/diodeinc/pcb.git
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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
88 lines
2.2 KiB
Python
88 lines
2.2 KiB
Python
"""Test for SPICE model of Crystal - demonstrates resonance behavior."""
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load("../../interfaces.zen", "Ground", "Net", "Power")
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load("../../properties.zen", "Simulation")
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Crystal = Module("../../generics/Crystal.zen")
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Capacitor = Module("../../generics/Capacitor.zen")
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Resistor = Module("../../generics/Resistor.zen")
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VIN = Power()
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PROBE = Net()
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XOUT = Net()
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GND = Ground()
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# 16MHz crystal in a Pierce-style test fixture with load capacitors.
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# Drive through a source resistor, crystal between PROBE and XOUT,
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# load caps on each side to ground.
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Resistor(
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name="R_SRC",
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value="1kOhm",
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package="0402",
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P1=VIN,
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P2=PROBE,
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)
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Crystal(
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name="Y1",
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package="2016_4Pin",
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frequency="16MHz",
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load_capacitance="12pF",
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XIN=PROBE,
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XOUT=XOUT,
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GND=GND,
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)
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# Load capacitors (typical Pierce oscillator configuration)
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Capacitor(
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name="C1",
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value="22pF",
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package="0402",
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P1=PROBE,
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P2=GND,
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)
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Capacitor(
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name="C2",
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value="22pF",
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package="0402",
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P1=XOUT,
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P2=GND,
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)
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Simulation(
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name="test_Crystal",
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setup=f"""
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* AC source for frequency sweep
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V1 {VIN} {GND} AC 1
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.control
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* Linear sweep around 16MHz to resolve the crystal resonance.
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* Crystal Q ~ 20000, so the series resonance 3dB bandwidth is only ~800Hz.
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* fs and fp are separated by ~27kHz (Cm=10fF, Cp=3pF).
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* Using linear sweep with fine resolution to capture these narrow features.
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ac lin 10000 15.9Meg 16.1Meg
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meas ac vmin_db min vdb({PROBE})
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meas ac vmax_db max vdb({PROBE})
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let swing = vmax_db - vmin_db
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* The crystal should produce a clearly visible resonance feature.
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* With Rm=50 Ohm and R_SRC=1kOhm, the series resonance dip should be
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* substantial (many dB).
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if swing < 3
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echo "FAIL: resonance swing only $&swing dB (expected clear series/parallel resonance)"
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quit 1
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end
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echo "PASS: vmin=$&vmin_db dB, vmax=$&vmax_db dB, swing=$&swing dB"
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set hcopydevtype = svg
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hardcopy output/crystal_magnitude.svg vdb({PROBE}) vdb({XOUT}) title "Crystal Frequency Response - Magnitude (16MHz)" xlabel Frequency ylabel Magnitude
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hardcopy output/crystal_phase.svg vp({PROBE}) vp({XOUT}) title "Crystal Frequency Response - Phase (16MHz)" xlabel Frequency ylabel Phase
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.endc
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""",
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)
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