Figure 0.7, Ideal Biasing Circuit for an NPN Bipolar Junction Transistor. On the left is a battery labeled V subscript BB. All the letters in the symbol are upper case. In the following all symbols for voltages and currents are upper case. The negative end of the battery connects to common. The positive end connects to a resistor labeled R sub B. The other end of the resistor connects to the base of an N P N transistor. There is a current flowing in the resistor which is called I sub B. The direction of the current is into the transistor. The emitter of the transistor connects to common. The voltage between the emitter and base is V sub B E. A current is flowing in the wire that connects the emitter to common. It is indicated as I sub E. The direction of the current is out of the transistor. On the right is a battery which is called V sub CC. A reminder, all letters in symbols and names are upper case. The negative end of the battery connects to common. The positive end connects to a resistor that is called R sub C. The other end of the resistor connects to the collector of the transistor. There is a current flowing in the resistor which is named I sub C. The voltage between the emitter and collector is named V sub C E. This completes the verbal description.
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