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What are the parameters of a BJT amplifier?
For the design of the amplifier, the 3 parameter values required are VceSAT, ro and β. Derived from the transistor characteristics curve shown in BJT Figure 2 above, one can set an approximate Q-point (VCE and IC) in the active region and measure ro and β. We will solve for Vce and estimate IC.
What kind of transistor is used in LTspice?
For a simple tutorial, I decided to pick a transistor that has good datasheet and good pre-installed model in LTspice. Options were limited, so i picked 2SC4102, a small current transistor from ROHM. The Base-emitter voltage and output characteristics shown below are enough information to go.
What is the output of a common emitter amplifier?
With the values obtained during the design, LTspice simulation is constructed. Note that TA is set to 25*C. And the amplifier performance is shown below. Output amplitude is ±4.9V which is very close to the desired output of ±5V and gain of -49 is very close to the calculated gain of -48.
How to calculate collector current using BJT circuit?
If you can calculate the maximum current then the current though R1 is 1/10 of that according to one of the specs. You can calculate the collector current knowing Vcc and Vc and the resistance of Rc which you can calculate knowing the max current draw from the power supply and the current through R1.
How is the BJT biased in the active region?
The BJT is biased in the active region by dc voltage source VBE. e.g., Q-point is set at (IC, VCE) = (1.5 mA, 5 V) with IB= 15 µA (βF = 100) Total base-emitter voltage is: vBE = VBE + vbe Collector-emitter voltage is: vCE = VCC – iCRC This is the load line equation. 3 Transistor Amplifiers BJT Amplifier (cont.)
Which is the intrinsic representation of the BJT?
Small-Signal Operation BJT Hybrid-Pi Mode. • The hybrid-pi small-signal model is the intrinsic representation of the BJT. • Small-signal parameters are controlled by the Q-point and are independent of geometry of the BJT Transconductance: Input resistance: Output resistance:
Which is dependent on VBE, DC, and emitter bias?
The formula for IE shows that the emitter bias circuit is dependent on VBE and DC, both of which change with temperature and current As IC is independent of DC and VBE, emitter bias can provide a stable Q-point if properly designed. Example 6: Determine whether the transistor is biased in cutoff, saturation or linear region.