20.11.1 Temperature Coefficients for Semiconductor Diodes

For semiconductor diodes, the empirical equations describing the temperature coefficient dV _F/dT in mV/ C as a function of forward current I _F in mA are

where, for this example,

I _ff = final value of forward current

I _fv = variable value of forward current

We begin with the user-defined m-file below which we type in the Editor Window and we save it as diode.m

<font color="0000ff">function</font> dx=diode(t,x,Ifv)<font color="ff0000">%</font><font color="ff0000">% Model for gold-doped and non-gold-doped diodes</font><font color="ff0000">%</font>Vf1 = x(1);  <font color="ff0000">% Gold-doped diode forward voltage, volts</font>Vf2 = x(2);  <font color="ff0000">% Non-gold-doped diode forward voltage, volts</font>Iff = 100;   <font color="ff0000">% Iff = final value in of forward current in mA</font>dVf1 = 0.6*log10(Iff)-1.92;dVf2 = 0.33*log10(Iff-Ifv)-1.66; <font color="ff0000">% Ifv = variable value of forward current in mA</font>dx = [dVf1;dVf2];

To test this function for correctness, on MATLAB's Command Window we type and execute the command

[t,x,lfw]=ode45(@diode, [0 10],[1;10],[ ], 50)<span class="beginpage"> pagenum="20-66"><a name="2075"></a><a name="IDX-20-66"></a></span>

where the vector [0 10] specifies the start and the end of the simulation time, the vector [1 ;10] specifies an initial value column vector, the null vector [ ] can be used for other options, and the input value is set to 50.

Next, using the Editor Window we write the m-file below and...