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Configurable simulation temperature for diodes and transistors (#147) #243

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11 changes: 11 additions & 0 deletions src/com/lushprojects/circuitjs1/client/CirSim.java
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Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,17 @@ public class CirSim implements NativePreviewHandler {
int hintType = -1, hintItem1, hintItem2;
String stopMessage;

// simulation temperature in Kelvin, default 27 C (300.15K) like SPICE
static double temperature = 300.15;
// electron thermal voltage = k*T/q, recalculated when temperature changes
static double vt = 0.025865;

static void setTemperature(double tempKelvin) {
temperature = tempKelvin;
vt = 1.380649e-23 * tempKelvin / 1.602176634e-19;
DiodeModel.updateAllModels();
}

double minFrameRate = 20;
boolean developerMode;

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17 changes: 8 additions & 9 deletions src/com/lushprojects/circuitjs1/client/Diode.java
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Expand Up @@ -33,15 +33,16 @@ void setup(DiodeModel model) {
zvoltage = model.breakdownVoltage;
vscale = model.vscale;
vdcoef = model.vdcoef;

vzcoef = 1 / CirSim.vt;

// sim.console("setup " + leakage + " " + zvoltage + " " + model.emissionCoefficient + " " + vdcoef);

// critical voltage for limiting; current is vscale/sqrt(2) at
// this voltage
vcrit = vscale * Math.log(vscale/(Math.sqrt(2)*leakage));
// translated, *positive* critical voltage for limiting in Zener breakdown region;
// limitstep() uses this with translated voltages in an analogous fashion to vcrit.
vzcrit = vt * Math.log(vt/(Math.sqrt(2)*leakage));
vzcrit = CirSim.vt * Math.log(CirSim.vt/(Math.sqrt(2)*leakage));
if (zvoltage == 0)
zoffset = 0;
else {
Expand All @@ -59,8 +60,6 @@ void reset() {
lastvoltdiff = 0;
}

// Electron thermal voltage at SPICE's default temperature of 27 C (300.15 K):
static final double vt = 0.025865;
// The diode's "scale voltage", the voltage increase which will raise current by a factor of e.
double vscale;
// The multiplicative equivalent of dividing by vscale (for speed).
Expand All @@ -69,7 +68,7 @@ void reset() {
// Shockley curve, but flipped and translated. This curve removes the moderating influence
// of emcoef, replacing vscale and vdcoef with vt and vzcoef.
// vzcoef is the multiplicative equivalent of dividing by vt (for speed).
static final double vzcoef = 1 / vt;
double vzcoef;
// User-specified diode parameters for forward voltage drop and Zener voltage.
double fwdrop, zvoltage;
// The diode current's scale factor, calculated from the user-specified forward voltage drop.
Expand Down Expand Up @@ -111,17 +110,17 @@ void reset() {
vnew = -vnew - zoffset;
vold = -vold - zoffset;

if (vnew > vzcrit && Math.abs(vnew - vold) > (vt + vt)) {
if (vnew > vzcrit && Math.abs(vnew - vold) > (CirSim.vt + CirSim.vt)) {
if(vold > 0) {
arg = 1 + (vnew - vold) / vt;
arg = 1 + (vnew - vold) / CirSim.vt;
if(arg > 0) {
vnew = vold + vt * Math.log(arg);
vnew = vold + CirSim.vt * Math.log(arg);
//System.out.println(oo + " " + vnew);
} else {
vnew = vzcrit;
}
} else {
vnew = vt *Math.log(vnew/vt);
vnew = CirSim.vt *Math.log(vnew/CirSim.vt);
}
sim.converged = false;
}
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22 changes: 15 additions & 7 deletions src/com/lushprojects/circuitjs1/client/DiodeModel.java
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Expand Up @@ -28,8 +28,6 @@ public class DiodeModel implements Editable, Comparable<DiodeModel> {
boolean internal;
static final int FLAGS_SIMPLE = 1;

// Electron thermal voltage at SPICE's default temperature of 27 C (300.15 K):
static final double vt = 0.025865;
// The diode's "scale voltage", the voltage increase which will raise current by a factor of e.
double vscale;
// The multiplicative equivalent of dividing by vscale (for speed).
Expand Down Expand Up @@ -142,7 +140,7 @@ static DiodeModel getModelWithParameters(double fwdrop, double zvoltage) {
}

// create a new one, converting to new parameter values
final double vscale = emcoef * vt;
final double vscale = emcoef * CirSim.vt;
final double vdcoef = 1 / vscale;
double leakage = 1 / (Math.exp(fwdrop * vdcoef) - 1);
String name = "fwdrop=" + fwdrop;
Expand Down Expand Up @@ -170,6 +168,16 @@ static void loadInternalModel(String s) {
dm.builtIn = dm.internal = true;
}

static void updateAllModels() {
if (modelMap == null)
return;
Iterator it = modelMap.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<String,DiodeModel> pair = (Map.Entry)it.next();
pair.getValue().updateModel();
}
}

static void clearDumpedFlags() {
if (modelMap == null)
return;
Expand Down Expand Up @@ -314,21 +322,21 @@ public void setEditValue(int n, EditInfo ei) {
// set emission coefficient for simple mode if we have enough data
void setEmissionCoefficient() {
if (forwardCurrent > 0 && forwardVoltage > 0)
emissionCoefficient = (forwardVoltage/Math.log(forwardCurrent/saturationCurrent+1)) / vt;
emissionCoefficient = (forwardVoltage/Math.log(forwardCurrent/saturationCurrent+1)) / CirSim.vt;

seriesResistance = 0;
}

public void setForwardVoltage() {
if (forwardCurrent == 0)
forwardCurrent = 1;
forwardVoltage = emissionCoefficient*vt * Math.log(forwardCurrent/saturationCurrent+1);
forwardVoltage = emissionCoefficient*CirSim.vt * Math.log(forwardCurrent/saturationCurrent+1);
}

void updateModel() {
vscale = emissionCoefficient * vt;
vscale = emissionCoefficient * CirSim.vt;
vdcoef = 1/vscale;
fwdrop = Math.log(1/saturationCurrent + 1) * emissionCoefficient * vt;
fwdrop = Math.log(1/saturationCurrent + 1) * emissionCoefficient * CirSim.vt;
}

String dump() {
Expand Down
15 changes: 12 additions & 3 deletions src/com/lushprojects/circuitjs1/client/EditOptions.java
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Expand Up @@ -91,12 +91,14 @@ public EditInfo getEditInfo(int n) {
ei.checkbox = new Checkbox("Auto-Run DC Operating Point on Reset", app.autoDCOnReset);
return ei;
}
if (n == 15) {
if (n == 15)
return new EditInfo("Simulation Temperature (\u00b0C)", CirSim.temperature - 273.15, 0, 0);
if (n == 16) {
EditInfo ei = new EditInfo("", 0, -1, -1);
ei.checkbox = new Checkbox("Auto-Adjust Timestep", sim.adjustTimeStep);
return ei;
}
if (n == 16 && sim.adjustTimeStep)
if (n == 17 && sim.adjustTimeStep)
return new EditInfo("Minimum time step size (s)", sim.minTimeStep, 0, 0).setPositive();

// don't add new options here. they are only visible if sim.adjustTimeStemp is set, and it isn't by default.
Expand Down Expand Up @@ -194,10 +196,17 @@ public void setEditValue(int n, EditInfo ei) {
if (n == 14)
app.autoDCOnReset = ei.checkbox.getState();
if (n == 15) {
double tempK = ei.value + 273.15;
if (tempK > 0) {
CirSim.setTemperature(tempK);
app.updateModels();
}
}
if (n == 16) {
sim.adjustTimeStep = ei.checkbox.getState();
ei.newDialog = true;
}
if (n == 16)
if (n == 17 && ei.value > 0)
sim.minTimeStep = ei.value;
}

Expand Down
30 changes: 14 additions & 16 deletions src/com/lushprojects/circuitjs1/client/TransistorElm.java
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Expand Up @@ -76,7 +76,7 @@ public TransistorElm(int xa, int ya, int xb, int yb, int f, StringTokenizer st)
void setup() {
model = TransistorModel.getModelWithNameOrCopy(modelName, model);
modelName = model.name; // in case we couldn't find that model
vcrit = vt * Math.log(vt/(Math.sqrt(2)*model.satCur));
vcrit = CirSim.vt * Math.log(CirSim.vt/(Math.sqrt(2)*model.satCur));
noDiagonal = true;
}
boolean nonLinear() { return true; }
Expand Down Expand Up @@ -251,24 +251,22 @@ void addRoutingObstacle(WireRouter router) {
}

static final double leakage = 1e-13; // 1e-6;
// Electron thermal voltage at SPICE's default temperature of 27 C (300.15 K):
static final double vt = 0.025865;
double vcrit;
double lastvbc, lastvbe;
double limitStep(double vnew, double vold) {
double arg;
double oo = vnew;

if (vnew > vcrit && Math.abs(vnew - vold) > (vt + vt)) {
if (vnew > vcrit && Math.abs(vnew - vold) > (CirSim.vt + CirSim.vt)) {
if(vold > 0) {
arg = 1 + (vnew - vold) / vt;
arg = 1 + (vnew - vold) / CirSim.vt;
if(arg > 0) {
vnew = vold + vt * Math.log(arg);
vnew = vold + CirSim.vt * Math.log(arg);
} else {
vnew = vcrit;
}
} else {
vnew = vt *Math.log(vnew/vt);
vnew = CirSim.vt *Math.log(vnew/CirSim.vt);
}
sim.converged = false;
//System.out.println(vnew + " " + oo + " " + vold);
Expand Down Expand Up @@ -309,7 +307,7 @@ void startIteration() {
double cje = calcJunctionCap(vjBE, model.junctionCapBE, model.junctionPotBE, model.junctionExpBE);
// Add diffusion capacitance only in forward bias (like SPICE)
if (model.transitTimeF > 0 && vjBE > 0) {
double vtn = vt * model.emissionCoeffF;
double vtn = CirSim.vt * model.emissionCoeffF;
cje += model.transitTimeF * model.satCur * Math.exp(vjBE / vtn) / vtn;
}
geqBE = 2 * cje / sim.timeStep;
Expand All @@ -321,7 +319,7 @@ void startIteration() {
double cjc = calcJunctionCap(vjBC, model.junctionCapBC, model.junctionPotBC, model.junctionExpBC);
// Add diffusion capacitance only in forward bias (like SPICE)
if (model.transitTimeR > 0 && vjBC > 0) {
cjc += model.transitTimeR * model.satCur * Math.exp(vjBC / (vt * model.emissionCoeffR)) / (vt * model.emissionCoeffR);
cjc += model.transitTimeR * model.satCur * Math.exp(vjBC / (CirSim.vt * model.emissionCoeffR)) / (CirSim.vt * model.emissionCoeffR);
}
geqBC = 2 * cjc / sim.timeStep;
if (geqBC < 1e-20) { geqBC = ceqBC = capCurBC = 0; }
Expand Down Expand Up @@ -375,16 +373,16 @@ void doStep() {
double csat=model.satCur;
double oik=model.invRollOffF;
double c2=model.BEleakCur;
double vte=model.leakBEemissionCoeff*vt;
double vte=model.leakBEemissionCoeff*CirSim.vt;
double oikr=model.invRollOffR;
double c4=model.BCleakCur;
double vtc=model.leakBCemissionCoeff*vt;
double vtc=model.leakBCemissionCoeff*CirSim.vt;

// double rbpr=model.minBaseResist;
// double rbpi=model.baseResist-rbpr;
// double xjrb=model.baseCurrentHalfResist;

double vtn=vt*model.emissionCoeffF;
double vtn=CirSim.vt*model.emissionCoeffF;
double evbe, cbe, gbe, cben, gben, evben, evbc, cbc, gbc, cbcn, gbcn, evbcn;
double qb, dqbdve, dqbdvc, q2, sqarg, arg;
if(vbe > -5*vtn){
Expand All @@ -405,7 +403,7 @@ void doStep() {
gben = -c2/vbe;
cben=gben*vbe;
}
vtn=vt*model.emissionCoeffR;
vtn=CirSim.vt*model.emissionCoeffR;
if(vbc > -5*vtn) {
evbc=Math.exp(vbc/vtn);
cbc=csat*(evbc-1)+gmin*vbc;
Expand Down Expand Up @@ -557,19 +555,19 @@ void getInfo(String arr[]) {
double cjcVal = calcJunctionCap(vbc*pnp, model.junctionCapBC, model.junctionPotBC, model.junctionExpBC);
// Add diffusion capacitance from transit time
if (model.transitTimeF > 0) {
double vtn = vt * model.emissionCoeffF;
double vtn = CirSim.vt * model.emissionCoeffF;
double gdBE = model.satCur * Math.exp(vbe*pnp / vtn) / vtn;
cjeVal += model.transitTimeF * gdBE;
}
if (model.transitTimeR > 0) {
double vtn = vt * model.emissionCoeffR;
double vtn = CirSim.vt * model.emissionCoeffR;
double gdBC = model.satCur * Math.exp(vbc*pnp / vtn) / vtn;
cjcVal += model.transitTimeR * gdBC;
}
double cTotal = cjeVal + cjcVal;
if (cTotal > 0 && ic != 0) {
// gm = Ic / Vt (transconductance at operating point)
double gmVal = Math.abs(ic) / vt;
double gmVal = Math.abs(ic) / CirSim.vt;
double ft = gmVal / (2 * Math.PI * cTotal);
arr[8] = "ft = " + getUnitText(ft, "Hz");
}
Expand Down
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