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Analog Special-Function Subcircuit Library

SpiceSharpParser.CustomComponents.Analog provides portable functional models for the analog LTspice A-device families. Load them independently from the digital library:

using SpiceSharpParser.CustomComponents.Analog;

AnalogSubcircuitLibrary analog = AnalogSubcircuitLibrary.LoadBuiltIn();

The assembly embeds standard-analog.lib, and the NuGet package copies the same file to contentFiles/any/any/SpiceSharpParser.CustomComponents/Analog.

Included Components

API Subcircuit Ordered pins Function
AddSampleHold ANALOG_SAMPLE_HOLD INP, INN, CLK, SH, OUT, COM Differential track or rising-edge sample
AddOperationalTransconductanceAmplifier ANALOG_OTA IN1N, IN1P, IN2P, IN2N, RAIL, OUT, COM Four-quadrant transconductance stage
AddVoltageControlledVaristor ANALOG_VARISTOR CONTROL_P, CONTROL_N, OUT, COM Bidirectional controlled clamp
AddModulator ANALOG_MODULATOR FM, AM, OUT, COM MARK/SPACE oscillator with amplitude input

These are analog or mixed-signal subcircuits built from ordinary SpiceSharp entities. With UseCustomComponents() enabled, SpiceSharpParser accepts native eight-terminal A-device lines for SAMPLEHOLD, OTA, VARISTOR, MODULATE, and MODULATOR, then expands them through this library. The models target functional compatibility and do not promise solver-identical waveforms.

Behavior

Sample/hold

When SH exceeds REF, the output tracks V(INP,INN). With SH low, a rising CLK crossing samples the differential input and holds it. VHIGH and VLOW limit the stored result.

Operational transconductance amplifier

The OTA combines the two differential pairs:

RAW = (REF - V(IN1N,IN1P)) * V(IN2P,IN2N)

LINEAR=1 selects direct G*RAW + IOFFSET operation. The default limited mode uses ISRC, ISINK, and ASYM to shape the output current. The RAIL pin exposes VLOW.

Voltage-controlled varistor

The magnitude of V(CONTROL_P,CONTROL_N) sets the positive and negative clamp level. Beyond either level, RCLAMP determines the incremental resistance; inside the window, ROFF supplies leakage.

Modulator

FM interpolates linearly from SPACE at 0 V to MARK at 1 V. AM sets the sine-wave amplitude. Values outside the 0-to-1 V FM range extrapolate the frequency rather than clamp it.

Parameters and Defaults

Subcircuit Parameters and defaults
ANALOG_SAMPLE_HOLD REF=0.5 VHIGH=10 VLOW=-10 TPD=0 RIN=1G ROUT=1k COUT=500f RTRACK=1 CMEM=10p
ANALOG_OTA G=1 REF=0 IOUT=10u ISRC=10u ISINK=-10u IOFFSET=0 POWERUP=1 ASYM=0 LINEAR=0 ROUT=1T COUT=0 VHIGH=2 VLOW=0 RCLAMP=1
ANALOG_VARISTOR RCLAMP=1 ROFF=1T COUT=1p
ANALOG_MODULATOR MARK=1k SPACE=1k ROUT=1 COUT=1p CPHASE=1 AMDEFAULT=0

Parameter overrides use the same dictionary convention as other subcircuit facades:

analog.AddModulator(
    circuit,
    "XVCO",
    "fm",
    "am",
    "out",
    "0",
    new Dictionary<string, string>
    {
        ["SPACE"] = "1k",
        ["MARK"] = "2k",
    });

LTspice A-device Compatibility

The optional LTspiceADeviceCompatibilityGoldenTests suite executes each native A-device netlist unchanged in both LTspice and SpiceSharpParser, then compares their .MEAS results. Its analog cases cover SAMPLEHOLD, OTA, VARISTOR, and MODULATOR. Set LTSPICE_EXE to the LTspice executable path to enable the tests; they are skipped when it is unset.