Hfe VERSUS TEMPERATURE

We will now generate Hfe versus Ic curves at different temperatures. This is a typical curve found in most data sheets for BJTs. We will use almost the same Secondary Sweep that we used in Section 4.F.2, except that for the Secondary Sweep we will vary temperature rather than VCe- We will use the same circuit and setup as in Section 4.F.2, but we will modify the Nested Sweep. We will start with the circuit from the previous example  

Since we have already created a simulation profile from the previous example, we do not need to create a new profile, open the previous profile, select PSpice and then Edit Simulation Profile from the Capture menus  

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C yoNaga source P- Current source O Global parameter O Model parameter C- Iamperehve 

The Primary Sweep is set up from the previous example. It is set to sweep IB from 1 pA to 1 mA at 20 points per decade. Gick the LEFT mouse button on the text Secondary Sweep to display its setup  

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We see that Ic varies by about 40 jxA and VCe varies by about 200 mV over the range of the simulation. For the purposes of this simulation, these quantities will be assumed to be constant. Notice that the x-axis is automatically set to temperature. To plot Hfe versus temperature all we need to do is add the trace IC(Q1)/IB(Q1). The x-axis will automatically be set to temperature ... 

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