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Ebers–Moll model for an NPN transistor. [28] I B, I C and I E are the base, collector and emitter currents; I CD and I ED are the collector and emitter diode currents; α F and α R are the forward and reverse common-base current gains. Ebers–Moll model for a PNP transistor Approximated Ebers–Moll model for an NPN transistor in the ...
A bias network is selected to stabilize the operating point of the transistor, by reducing the following effects of device variability, temperature, and voltage changes: [1] The gain of a transistor can vary significantly between different batches, which results in widely different operating points for sequential units in serial production or ...
Figure 3: PNP version of the emitter-follower circuit, all polarities are reversed. A small voltage change on the input terminal will be replicated at the output (depending slightly on the transistor's gain and the value of the load resistance; see gain formula below). This circuit is useful because it has a large input impedance
In a diode model two diodes are connected back-to-back to make a PNP or NPN bipolar junction transistor (BJT) equivalent. This model is theoretical and qualitative. This model is theoretical and qualitative.
The expressions are derived for a PNP transistor. For an NPN transistor, n has to be replaced by p, and p has to be replaced by n in all expressions below. The following assumptions are involved when deriving ideal current-voltage characteristics of the BJT [7] Low level injection; Uniform doping in each region with abrupt junctions
The input signal is applied across the ground and the base circuit of the transistor. The output signal appears across ground and the collector of the transistor. Since the emitter is connected to the ground, it is common to signals, input and output. The common-emitter circuit is the most widely used of junction transistor amplifiers.
For larger source impedances, the gain is determined by the resistor ratio R L / R S, and not by the transistor properties, which can be an advantage where insensitivity to temperature or transistor variations is important. An alternative to the use of the hybrid-pi model for these calculations is a general technique based upon two-port ...
Darlington Transistor (NPN-type) In electronics, a Darlington configuration (commonly called as a Darlington pair) is a circuit consisting of two bipolar transistors with the emitter of one transistor connected to the base of the other, such that the current amplified by the first transistor is amplified further by the second one. [1]