Lab 13 TF EIM
DC Bipolar Transistor Curves
Data sheet for transistors.
Media:2N3904.pdfMedia:2N3906.pdf
Using 2N3904 is more srtaight forward in this lab.
Transistor circuit
1.) Identify the type (n-p-n or p-n-p) of transistor you are using and fill in the following specifications.
| Value | Description |
| Collector-Base breakdown voltage | |
| Emitter-Base Breakdown Voltage | |
| Maximum Collector Voltage | |
| Maximum Collector Current | |
| Transistor Power rating([math]\displaystyle{ P_{Max} }[/math]) | |
| DC current gain [math]\displaystyle{ h_{FE}( I_C, V_{CE}) }[/math] |
2.) Construct the circuit below according to the type of transistor you have.
Let [math]\displaystyle{ R_E = 100 \Omega }[/math].
[math]\displaystyle{ V_{CC} < 5 Volts }[/math] variable power supply
[math]\displaystyle{ V_{BE}= 1V }[/math].
Find the resistors you need to have
[math]\displaystyle{ I_B = 2 \mu A }[/math] , [math]\displaystyle{ 5 \mu A }[/math] , and [math]\displaystyle{ 10 \mu A }[/math]
3.) Measure the emitter current [math]\displaystyle{ I_E }[/math] for several values of [math]\displaystyle{ V_{CE} }[/math] by changing [math]\displaystyle{ V_{CC} }[/math] such that the base current [math]\displaystyle{ I_B = 2 \mu }[/math] A is constant. [math]\displaystyle{ I_B \approx \frac{V_{BB}-V_{BE}}{R_B} }[/math]
| V_{CC} | V_B | V_{BB} | V_ {EC} | V_ E | R_E | R_B | I_E | I_B |
| mV | mV | V | mV | mV | [math]\displaystyle{ \Omega }[/math] | k[math]\displaystyle{ \Omega }[/math] | mA | \muA |
4.) Repeat the previous measurements for [math]\displaystyle{ I_B \approx 5 \mbox{ and } 10 \mu }[/math] A. Remember to keep [math]\displaystyle{ I_CV_{CE} < P_{max} }[/math] so the transistor doesn't burn out
| V_{CC} | V_B | V_{BB} | V_ {EC} | V_ E | R_E | R_B | I_E | I_B |
| mV | mV | V | mV | mV | [math]\displaystyle{ \Omega }[/math] | k[math]\displaystyle{ \Omega }[/math] | mA | \muA |
5.) Graph [math]\displaystyle{ I_C }[/math] -vs- [math]\displaystyle{ V_{CE} }[/math] for each value of [math]\displaystyle{ I_B }[/math] and [math]\displaystyle{ V_{CC} }[/math] above. (40 pnts)
6.) Overlay points from the transistor's data sheet on the graph in part 5.).(10 pnts)
Questions
- Compare your measured value of [math]\displaystyle{ h_{FE} }[/math] or [math]\displaystyle{ \beta }[/math] for the transistor to the spec sheet? (10 pnts)
- What is [math]\displaystyle{ \alpha }[/math] for the transistor?(10 pnts)
- The base must always be more _________(________) than the emitter for a npn (pnp)transistor to conduct I_C.(10 pnts)
- For a transistor to conduct I_C the base-emitter junction must be ___________ biased.(10 pnts)
- For a transistor to conduct I_C the collector-base junction must be ___________ biased.(10 pnts)
Extra credit
Measure the Base-Emmiter breakdown voltage. (10 pnts)
I expect to see a graph [math]\displaystyle{ (I_{B} -vs- V_{BE} ) }[/math] and a linear fit which is similar to the forward biased diode curves. Compare your result to what is reported in the data sheet.