A common emitter is a type of electronic common emitter s-parameters: amplifier stage based on a bipolar transistor in common emitter amp series with a load element such as a resistor. The term "common common emitter configuration emitter" refers to the fact that the emitter node of the transistor (indicated by an arrow symbol) is connected to a "common" power rail, typically the common emitter amplifier 0 volt reference or ground node. The collector node is connected to the output load, and the base node acts common emitter amplifier tutorial as input.
The electronic circuit diagram (right) shows transistor amplifier common emitter a common emitter configuration with voltage divider bias (CEVDB). In the figure, the common emitter common emitter amplifier topology circuit is comprised of load resistor RC and transistor NPN with the output connected as shown; the other circuit elements are used for biasing the transistor and signal coupling/decoupling. The resistor RE between the emitter node and the shared ground appears at first glance to contradict the strict definition of "common emitter", but the term is still appropriate here because, for all frequencies of interest, the capacitor CE acts as a low impedance by decoupling the emitter to ground. The emitter resistor provides a form of negative feedback called emitter degeneration, which common emitter + bypass cap increases the stability and linearity of the amplifier, especially in response to temperature changes.
Common emitter circuits are used to amplify weak transistor bias common emitter amplifier voltage signals, such as the faint radio signals detected by an antenna. They are also used in common emitter oscillator a special analog circuit configuration known as a current mirror, where a single shared input is used to drive a set of identical transistors, each of whose current common emitter amplifier configurations drive output will be nearly identical to each other, even if they are driving dissimilar transistor common emitter amplifier output loads.
Small-signal characteristics
(The parallel lines indicate components in parallel.)
Inherent voltage gain:
- With CE:
- Without CE:
Input resistance:
- With CE:
- Without CE:
Current gain:
Output resistance:
The variables not listed in the schematic are:
- gm is the transconductance in siemens, calculated by gm = IC / VT, where:
- IC is the collector bias current
- VT = kT / q is the thermal voltage, calculated from Boltzmann's constant, the charge on an electron, and the transistor temperature in kelvins. At room temperature this is about 25 mV (Google calculator). common emitter
- IC is the collector bias current
- β0 = IC / IB is the current gain at low frequencies (commonly called hFE). This is a parameter specific to each transistor, and can be found on a datasheet.
- rπ = β0 / gm = VT / IB
Transistor common emitter amplifier gain amplifiers
- Common emitter
- Common collector
- Common base
- Common source
- Common drain
- Common gate
Electronics Topics
The field of electronics is the study and use of systems that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. The design and construction of electronic circuits to solve practical problems is part of the fields of electronic engineering, and the hardware design side of computer engineering. The study of new semiconductor devices and their technology is sometimes considered as a branch of physics.
# - A | B | Co - Cz | C - Cm | D
Em - F | E - El | G - H | I - K | L - Ma
