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Bipolar transistors have four distinct regions of operation, defined by BJT junction biases: [9] [10] Forward-active (or simply active) The base–emitter junction is forward biased and the base–collector junction is reverse biased. Most bipolar transistors are designed to afford the greatest common-emitter current gain, β F, in
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.
A multiple-emitter transistor is a specialized bipolar transistor mostly used at the inputs of integrated circuit TTL NAND logic gates. Input signals are applied to the emitters . The voltage presented to the following stage is pulled low if any one or more of the base–emitter junctions is forward biased, allowing logical operations to be ...
As an example of the need for careful biasing, consider a transistor amplifier. In linear amplifiers , a small input signal gives a larger output signal without any change in shape (low distortion): the input signal causes the output signal to vary up and down about the Q-point in a manner strictly proportional to the input.
Date/Time Thumbnail Dimensions User Comment; current: 01:52, 23 August 2006: 740 × 400 (87 KB): Matt Britt == Summary == Energy band diagram of a simple NPN bipolar junction transistor in forward-active mode showing electron energy versus position.
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 ...
PN junction operation in forward-bias mode, showing reducing depletion width. In forward bias, the p-type is connected with a positive electrical terminal and the n-type is connected with a negative terminal. The panels show energy band diagram, electric field, and net charge density. The built-in potential of the semiconductor varies ...
[1] [2] [3] In order to achieve this with a bipolar transistor, the transistor is biased. [1] [3] Faithful amplification can only occur on transistors with a forward biased emitter-base junction, a reverse biased collector-base junction, and proper zero signal collector current.