Bipolar-Junction Transistors - Revision history

TimVK4YEH: added external links

2010-12-19T06:19:34Z

added external links

← Older revision		Revision as of 23:19, 18 December 2010
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	When a BJT is used as a switch or oscillator, it moves back and forth between cutoff (off) and saturated (on). Most amplifier designs attempt to keep the transistor in the active region, in order to keep the response [[linear]].		When a BJT is used as a switch or oscillator, it moves back and forth between cutoff (off) and saturated (on). Most amplifier designs attempt to keep the transistor in the active region, in order to keep the response [[linear]].

			==More information==

			* [http://en.wikipedia.org/wiki/Bipolar_junction_transistor Wikipedia]
			* [http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/info/comp/active/BiPolar/page1.html University of St Andrews]
			* [http://www.electronics-tutorials.ws/transistor/tran_1.html Electronics Tutorials]
			* [http://www.allaboutcircuits.com/vol_3/chpt_4/1.html All about circuits]

	== Circuit Design ==		== Circuit Design ==

	=== Biasing ===		=== Biasing ===

			* [http://en.wikipedia.org/wiki/Bipolar_transistor_biasing Wikipedia article]
			* [http://www.allaboutcircuits.com/worksheets/bjtbias.html All about circuits]
			* [http://www.hobbyprojects.com/junction_transistors/junction_transistor_biasing.html Hobby Projects Junction Transistor Biasing]

	=== Small-signal analysis ===		=== Small-signal analysis ===
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	=== Ebers-Moll ===		=== Ebers-Moll ===

			* [http://ecee.colorado.edu/~bart/book/book/chapter5/ch5_3.htm#5_3_3 Ebers-Moll model of a BJT]
	{{electronics}}		{{electronics}}

TimVK4YEH: some info

2010-11-09T03:47:46Z

some info

← Older revision		Revision as of 20:47, 8 November 2010
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	=== Terminals ===		=== Terminals ===

	~~There~~ are three terminals on each transistor, known as '''Emitter''', '''Base''', and '''Collector'''. A small current flowing between base and emitter can effectively control a much larger current flowing between collector and emitter. (Note that emitter and collector are not interchangable, although the symmetry of NPN or PNP might lead one to think that they are.)		As seen in the two diagrams above, there are three terminals on each transistor, known as '''Emitter''' (E), '''Base''' (B), and '''Collector''' (C). A small current flowing between base and emitter can effectively control a much larger current flowing between collector and emitter. (Note that emitter and collector are not interchangable, although the symmetry of NPN or PNP might lead one to think that they are.)

	=== Operating Regions ===		=== Operating Regions ===

TimVK4YEH: /* NPN vs. PNP */

2010-11-09T03:46:18Z

NPN vs. PNP

← Older revision		Revision as of 20:46, 8 November 2010
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	NPN devices are used somewhat more often than PNP devices.		NPN devices are used somewhat more often than PNP devices.

			[[Image:NPN.png \| 120px]]

			NPN transistor circuit symbol

			[[Image:PNP.png \| 120px]]

			PNP transistor circuit symbol

	=== Terminals ===		=== Terminals ===

TimVK4YEH: fixed internal links

2009-07-02T01:03:38Z

fixed internal links

← Older revision		Revision as of 18:03, 1 July 2009
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	In the '''cutoff''' region, no current flows into the base. The voltage at the base is typically close to that at the emitter. The transistor can be viewed as turned off.		In the '''cutoff''' region, no current flows into the base. The voltage at the base is typically close to that at the emitter. The transistor can be viewed as turned off.

	In the '''active''' region, the base/emitter junction is [[~~diode~~#~~Forward and Reverse Bias~~\|forward biased]] and the collector/base junction is [[~~diode~~#~~Forward and Reverse Bias~~\|reverse biased]]. The current flowing from collector to emitter is given by		In the '''active''' region, the base/emitter junction is [[Diodes#What_are_the_electrical_characteristics_of_a_diode.3F\|forward biased]] and the collector/base junction is [[Diodes#What_are_the_electrical_characteristics_of_a_diode.3F\|reverse biased]]. The current flowing from collector to emitter is given by

TimVK4YEH: /* The P-N junction */

2009-07-02T01:01:03Z

The P-N junction

← Older revision		Revision as of 18:01, 1 July 2009
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	The BJT is based on the P-N junction, a joint between '''doped silicon''' which has an excess of free electrons ('''N''' for negative) and doped silicon with an excess of '''holes''', locations in the crystal lattice where electrons can fit and be absorbed ('''P''' for positive).		The BJT is based on the P-N junction, a joint between '''doped silicon''' which has an excess of free electrons ('''N''' for negative) and doped silicon with an excess of '''holes''', locations in the crystal lattice where electrons can fit and be absorbed ('''P''' for positive).

	A [[diode]] consists of a single P-N junction. When the P material is connected to a positive voltage and N a negative voltage, current flows through the junction with a voltage drop of about 0.6 volts. When P is connected to negative and N to positive, no current flows.		A [[Diodes \|diode]] consists of a single P-N junction. When the P material is connected to a positive voltage and N a negative voltage, current flows through the junction with a voltage drop of about 0.6 volts. When P is connected to negative and N to positive, no current flows.

	=== NPN vs. PNP ===		=== NPN vs. PNP ===

Carlb: /* Ebers-Moll */

2009-04-09T01:20:13Z

Ebers-Moll

← Older revision		Revision as of 18:20, 8 April 2009
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	=== Ebers-Moll ===		=== Ebers-Moll ===


			{{electronics}}

YL: Corrected "electronics" to "electrons".

2008-03-29T02:25:50Z

Corrected "electronics" to "electrons".

← Older revision		Revision as of 19:25, 28 March 2008
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	=== NPN vs. PNP ===		=== NPN vs. PNP ===

	A BJT consists of two P-N junctions immediately adjacent to each other, close enough that ~~electronics~~ crossing one junction can interact with the other. It can either be an NPN transistor, with a piece of P material between two pieces of N material, or a PNP transistor, with a piece of N between two pieces of P. The two types of device behave exactly the same except for the reversal of polarity.		A BJT consists of two P-N junctions immediately adjacent to each other, close enough that electrons crossing one junction can interact with the other. It can either be an NPN transistor, with a piece of P material between two pieces of N material, or a PNP transistor, with a piece of N between two pieces of P. The two types of device behave exactly the same except for the reversal of polarity.

	NPN devices are used somewhat more often than PNP devices.		NPN devices are used somewhat more often than PNP devices.

YL: /* Operating Regions */

2008-03-13T21:51:04Z

Operating Regions

← Older revision		Revision as of 14:51, 13 March 2008
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	=== Operating Regions ===		=== Operating Regions ===

	A BJT can operate in one of three regions: the active region, the ~~Cutoff~~ region, and the saturated region.		A BJT can operate in one of three regions: the active region, the cutoff region, and the saturated region.

	In the '''cutoff''' region, no current flows into the base. The voltage at the base is typically close to that at the emitter. The transistor can be viewed as turned off.		In the '''cutoff''' region, no current flows into the base. The voltage at the base is typically close to that at the emitter. The transistor can be viewed as turned off.

YL: /* NPN vs. PNP */

2008-03-13T21:49:35Z

NPN vs. PNP

← Older revision		Revision as of 14:49, 13 March 2008
Line 13:		Line 13:
	=== NPN vs. PNP ===		=== NPN vs. PNP ===

	A BJT consists of two P-N ~~junction~~ immediately adjacent to each other, close enough that electronics crossing one junction can interact with the other. It can either be an NPN transistor, with a piece of P material between two pieces of N material, or a PNP transistor, with a piece of N between two pieces of P. The two types of device behave exactly the same except for the reversal of polarity.		A BJT consists of two P-N junctions immediately adjacent to each other, close enough that electronics crossing one junction can interact with the other. It can either be an NPN transistor, with a piece of P material between two pieces of N material, or a PNP transistor, with a piece of N between two pieces of P. The two types of device behave exactly the same except for the reversal of polarity.

	NPN devices are used somewhat more often than PNP devices.		NPN devices are used somewhat more often than PNP devices.

YL: /* Biasing */

2008-03-11T00:09:27Z

Biasing

← Older revision		Revision as of 17:09, 10 March 2008
Line 39:		Line 39:
	When a BJT is used as a switch or oscillator, it moves back and forth between cutoff (off) and saturated (on). Most amplifier designs attempt to keep the transistor in the active region, in order to keep the response [[linear]].		When a BJT is used as a switch or oscillator, it moves back and forth between cutoff (off) and saturated (on). Most amplifier designs attempt to keep the transistor in the active region, in order to keep the response [[linear]].

	== Biasing ==		== Circuit Design ==

			=== Biasing ===

			=== Small-signal analysis ===

			=== Transistor nonlinearity ===

			=== Ebers-Moll ===