billrussell42
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It's usually a voltage applied to the base via a voltage divider of two resistors. And an emitter resistor. The emitter resistor can be bypassed via a capacitor.
Typical values are a Re such that Ve = 1 to 2 volts. The voltage divider would set the base voltage to a value 0.6 volts higher than the emitter voltage. A collector resistor is used for the output.
Typical values, for a 12 volt supply and 10 mA of collector current:
Vc = 6.5 volts, so Rc = 5.5/10 = 550 ohms
Ve = 1v, so Re = 1/10 = 100 ohms
Vb = 1.6 volts
Bottom base divider resistor (setting current to 1 mA) is 1600
Top is 10.4k
That is the best bias method. But there are others.
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Is determined by what you mean by output. What do you want to do with it. It could be easier when you had a precise circuit in mind. All the matters below are effected by means of now not simply the bias point but with the aid of circuit design, by using provide voltages, with the aid of resistor and cap values, through kind of transistor. Output maximum voltage is a perform of the bias point. Ideally it should have the collector at half the deliver voltage, assuming the emitter is grounded. If no longer, half of the Vs-Ve voltage. Output impedance is a intricate function of bias features. Typically you need extra current in the collector for a cut back impedance output. Reap is a function of a lot of things. If the circuit kind is fixed, then you want the collector present and voltage to be at a point the place HFE is perfect, or virtually it. Frequency response is a further complex one. Regularly you must maintain the impedances low for higher frequency response, because of this lower give voltages and larger currents. I have no idea if that is what you are watching for? Which you could contact me.
Vijayan S
Biasing is kind of a constant voltage appied to the base of a Transistor, to make sure it ampifies both positive and negative signals equally and faithfully. Without bias it can amplfy only positive signals, and when we apply a negative signal the transistor will enter into reverse bias condition. That is why we set the collector voltage to approximately half the value of the power supply voltage, so that the output voltage ie the collector voltage swings from the bias voltage to the Vcc and to the zero. Striclty speaking the output will not reach the exact Vcc value but will be always lesser than that, same as the output will not be zero but it will be near to zero ie the saturation value 0.2 volts.
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In an amplifier the transistor must be biased in their active region. Usually the bias currents will be much larger than the signal currents.