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Another useful characteristic is the common-base current gain, α F. The common-base current gain is approximately the gain of current from emitter to collector in the forward-active region. This ratio usually has a value close to unity; between 0.980 and 0.998. It is less than unity due to recombination of charge carriers as they cross the ...
The 1967 RCA Transistor Manual, SC-13, did not mention any measure of high frequency performance for the 2N3055; by the 1971 SC-15 manual a transition frequency, f T, of at least 800 kHz was specified (at I C = 1 A) and f hfe (the frequency at which the small-signal current gain drops by 3 dB) was also specified at 1 A to be 10 kHz minimum.
It offers high current gain (typically 200), medium input resistance and a high output resistance. The output of a common emitter amplifier is inverted; i.e. for a sine wave input signal, the output signal is 180 degrees out of phase with respect to the input.
In other words, the circuit has current gain (which depends largely on the h FE of the transistor) instead of voltage gain. A small change to the input current results in much larger change in the output current supplied to the output load. One aspect of buffer action is transformation of impedances.
The current gain is very nearly unity as long as R S ≫ r E. An alternative analysis technique is based upon two-port networks . For example, in an application like this one where current is the output, an h-equivalent two-port is selected because it uses a current amplifier in the output port.
A 2N3904 made by Motorola.The pinout from left to right is: Emitter, Base, Collector. [1] A 2N3904 (lower left) in a TO-92 package on a breadboard. The 2N3904 is a common NPN bipolar junction transistor used for general-purpose low-power amplifying or switching applications.
A Darlington pair behaves like a single transistor, meaning it has one base, collector, and emitter. It typically creates a high current gain (approximately the product of the gains of the two transistors, because their β values multiply together). A general relation between the compound current gain and the individual gains is given by:
The 2N2907 is a commonly available PNP bipolar junction transistor used for general purpose low-power amplifying or switching applications. It is designed for low to medium current, low power, medium voltage, and can operate at moderately high speeds.