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https://github.com/diodeinc/pcb.git
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Akhil Velagapudi
6f29672259
Create vdrop_dc in the const plot before the first analysis so later AC and transient plots do not hide the DC result. Amp-Thread-ID: https://ampcode.com/threads/T-01a05503-b971-744a-92d7-4a79c32b168b
97 lines
2.8 KiB
Python
97 lines
2.8 KiB
Python
"""Test for SPICE model of Inductor - verifies DCR and self-resonance behavior."""
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load("../../interfaces.zen", "Ground", "Net", "Power")
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load("../../properties.zen", "Simulation")
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Inductor = Module("../../generics/Inductor.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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GND = Ground()
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# 10uH 0805 inductor with a load resistor
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Inductor(
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name="L1",
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value="10uH",
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package="0805",
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P1=VIN,
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P2=PROBE,
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)
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# Load resistor
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Resistor(
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name="R_LOAD",
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value="50Ohm",
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package="0603",
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P1=PROBE,
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P2=GND,
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)
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Simulation(
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name="test_Inductor",
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setup=f"""
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* 3.3V DC bias + 1V AC stimulus, plus square wave for transient
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V1 {VIN} {GND} DC 3.3 AC 1 PULSE(0 5 0 10n 10n 1u 2u)
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.control
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* Create scalars in the const plot before any analysis.
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let vdrop_dc = 0
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* --- DC test: inductor should pass DC with small drop from DCR ---
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op
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let vdrop_dc = v({VIN}) - v({PROBE})
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* A 10uH 0805 inductor has DCR ~ 0.15 Ohm. With 50 Ohm load at 3.3V,
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* the DC drop across the inductor should be tiny (< 0.1V).
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* An ideal inductor would have zero drop.
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if vdrop_dc > 0.1
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echo "FAIL: DC voltage drop across inductor is $&vdrop_dc V (expected < 0.1V)"
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echo " The model has too much DC resistance"
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quit 1
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end
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* --- AC test: should show inductive behavior, then self-resonance ---
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ac dec 200 1k 1g
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meas ac gain_1k find vdb({PROBE}) at=1k
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meas ac gain_1M find vdb({PROBE}) at=1Meg
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meas ac gain_100M find vdb({PROBE}) at=100Meg
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* At 1kHz the 10uH inductor has |XL| ~ 0.063 Ohm, negligible vs 50 Ohm load.
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* Signal should pass through nearly unattenuated (gain ~ 0dB).
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if gain_1k < -1
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echo "FAIL: 1kHz insertion loss too high: $&gain_1k dB (inductor should be transparent at low freq)"
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quit 1
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end
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* At 1MHz, |XL| ~ 63 Ohm, comparable to 50 Ohm load.
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* Expect some attenuation (~-3 to -6 dB range).
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if gain_1M > -1
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echo "FAIL: 1MHz gain too high: $&gain_1M dB (inductor should have significant reactance)"
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quit 1
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end
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* At 100MHz we should be near or past SRF (~15MHz for 10uH).
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* Above SRF the parasitic capacitance dominates and impedance drops.
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* Gain should recover somewhat compared to the SRF region.
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echo "PASS: DC_drop=$&vdrop_dc V, gain(1kHz)=$&gain_1k dB, gain(1MHz)=$&gain_1M dB, gain(100MHz)=$&gain_100M dB"
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set hcopydevtype = svg
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hardcopy output/inductor.svg vdb({PROBE}) title "Inductor Filter Response (10uH 0805)" xlabel Frequency ylabel Magnitude
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* --- Transient test: RL step response ---
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tran 10n 10u uic
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set hcopydevtype = svg
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hardcopy output/inductor_transient.svg v({VIN}) v({PROBE}) title "Inductor: RL Step Response" xlabel Time ylabel Voltage
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.endc
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""",
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)
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# pcb:sch GND.0 x=49.8000 y=-216.9000 rot=0
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# pcb:sch L1.L x=-51.8000 y=-432.8000 rot=-90
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# pcb:sch R_LOAD.R x=52.3400 y=-343.9000 rot=0
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# pcb:sch VIN.0 x=-173.7200 y=-470.9000 rot=0
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