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If this is the case, the collector–emitter current is approximately proportional to the base current, but many times larger, for small base current variations. Reverse-active (or inverse-active or inverted) By reversing the biasing conditions of the forward-active region, a bipolar transistor goes into reverse-active mode.
As the transistor provides current gain, it facilitates the switching of a relatively large current in the collector by a much smaller current into the base terminal. The ratio of these currents varies depending on the type of transistor, and even for a particular type, varies depending on the collector current.
Figure 1: Basic NPN common base circuit (neglecting biasing details). In electronics, a common-base (also known as grounded-base) amplifier is one of three basic single-stage bipolar junction transistor (BJT) amplifier topologies, typically used as a current buffer or voltage amplifier.
A load line diagram, illustrating an operating point in the transistor's active region.. Biasing is the setting of the DC operating point of an electronic component. For bipolar junction transistors (BJTs), the operating point is defined as the steady-state DC collector-emitter voltage and the collector current with no input signal applied.
The 2N3904 is an NPN transistor that can only switch one-third the current of the 2N2222 but has otherwise similar characteristics. The 2N3904 exhibits its forward gain (beta) peak at a lower current than the 2N2222, and is useful in amplifier applications with reduced I c, e.g., (gain peak at 10 mA for the 2N3904 but 150 mA for the 2N2222).
The base circuit is modified to operate the transistor in class-B or AB mode. In class-A mode, sometimes an active current source is used instead of R E (Fig. 4) to improve linearity and/or efficiency.
The low-current input terminal into the point-contact transistor is the emitter, while the output high current terminals are the base and collector. This differs from the later type of bipolar junction transistor invented in 1951 that operates as transistors still do, with the low current input terminal as the base and the two high current ...
Early, is the variation in the effective width of the base in a bipolar junction transistor (BJT) due to a variation in the applied base-to-collector voltage. A greater reverse bias across the collector–base junction, for example, increases the collector–base depletion width, thereby decreasing the width of the charge carrier portion of the ...
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