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Transistors - Bipolar (BJT) - Single

Image Part Number Description / PDF Quantity Rfq
ZXTN618MATA

ZXTN618MATA

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 20V 4.5A 3-DFN

2950
ZXTP2027FTA

ZXTP2027FTA

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 60V 4A SOT23-3

11296
BC817-16-7-F

BC817-16-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 45V 500MA SOT23-3

62081
DSS4240T-7

DSS4240T-7

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 40V 2A SOT-23

236517
2DD1621T-13

2DD1621T-13

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 25V 2A SOT89-3

280
BC847BLP4-7B

BC847BLP4-7B

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 45V 0.1A DFN1006H4-3

995590000
ZTX948

ZTX948

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 20V 4.5A E-LINE

1901
ZXTP25012EFHTA

ZXTP25012EFHTA

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 12V 4A SOT23-3

238139000
BC817-25Q-7-F

BC817-25Q-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 45V 500MA SOT23-3

26209
ZTX657STZ

ZTX657STZ

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 300V 0.5A E-LINE

10000
BC817-16Q-7-F

BC817-16Q-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 45V 500MA SOT23

281718000
FMMT459TA

FMMT459TA

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 450V 0.15A SOT23-3

38950
ZTX857

ZTX857

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 300V 3A E-LINE

3666
2DD1664P-13

2DD1664P-13

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 32V 1A SOT89-3

985
FMMT591ATC

FMMT591ATC

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 40V 1A SOT23-3

2147483647
BC848A-7-F

BC848A-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 30V 0.1A SOT23-3

2147483647
2DD2098R-13

2DD2098R-13

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 20V 5A SOT89-3

0
FMMT591AQTA

FMMT591AQTA

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 40V 1A SOT23-3

1558120000
MMBT3906T-7-F

MMBT3906T-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS PNP 40V 0.2A SOT523

0
2DC4617Q-7-F

2DC4617Q-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS NPN 50V 0.15A SOT523

3548

Transistors - Bipolar (BJT) - Single

1. Overview

Bipolar Junction Transistors (BJTs) are three-terminal semiconductor devices that use both electron and hole charge carriers. They form the foundation of analog electronics through their ability to amplify signals and control current flow. BJTs remain critical in modern electronics for applications ranging from audio amplifiers to power management circuits, offering superior linearity and robustness in switching operations.

2. Main Types & Functional Classification

TypeFunctional CharacteristicsApplication Examples
NPN TransistorMajority carriers: electrons. Requires positive base current for conduction.Low-noise amplifiers, digital logic circuits
PNP TransistorMajority carriers: holes. Conducts with negative base current.Power supply circuits, motor controllers
High-Frequency BJTOptimized for RF/microwave signal amplification (fT > 100 MHz)Wireless communication systems, radar
Power BJTHigh current/voltage ratings (IC > 1A, VCE > 50V)Switch-mode power supplies, motor drives

3. Structure & Composition

BJTs consist of three doped semiconductor regions forming two p-n junctions:

  • Emitter: Heavily doped region emitting charge carriers
  • Base: Thin, lightly doped middle region controlling carrier flow
  • Collector: Moderately doped region collecting carriers

Manufactured using silicon (common) or germanium (historic) with planar processing technology. The structure forms either NPN (n-type emitter/base/collector) or PNP configuration, with metal contacts for external connections.

4. Key Technical Specifications

ParameterDescriptionImportance
Current Gain (hFE)Ratio of collector to base current (10-1000)Determines amplification capability
Transition Frequency (fT)Frequency at which current gain drops to 1Limits high-frequency performance
Max Collector Current (ICmax)Maximum allowable continuous collector currentDefines power handling capability
Breakdown Voltage (VCEO)Max voltage between collector and emitterPrevents device failure under stress
Saturation Voltage (VCEsat)Voltage drop in fully conducting stateAffects power efficiency in switching

5. Application Areas

  • Consumer Electronics: Audio amplifiers, LED drivers
  • Automotive: Engine control units, electric vehicle inverters
  • Industrial: PLCs, motor controllers
  • Telecommunications: RF power amplifiers, fiber optic transceivers
  • Aerospace: Avionics systems, satellite transponders

6. Leading Manufacturers & Products

ManufacturerProduct SeriesKey SpecificationsTypical Use
ON Semiconductor2N3904hFE: 100-300, fT: 300 MHzGeneral-purpose switching
InfineonBC547VCEO: 50V, ICmax: 100mAAnalog signal amplification
STMicroelectronics2SD2656ICmax: 15A, VCEO: 80VPower inverter applications
Diodes Inc.BFR93AfT: 10 GHz, Noise Figure: 2dBHigh-frequency front-end amplifiers

7. Selection Guidelines

  • Determine operating frequency: Select fT > 3 target frequency
  • Power requirements: Ensure Icmax and VCEO exceed circuit requirements by 20%
  • Thermal considerations: Calculate power dissipation (P=VCE IC)
  • Package type: TO-92 for low power, TO-220 for high-power applications
  • Environmental factors: Consider temperature ratings for industrial/military use

8. Industry Trends

Future developments include:

  • High-frequency BJTs operating beyond 100 GHz for 6G communication
  • Integrated BJT-MOSFET hybrid devices (BiCMOS) for mixed-signal applications
  • Wide-bandgap materials (SiC/GaN) for higher power density
  • Miniaturization through chip-scale packaging
  • Improved thermal management solutions for automotive applications
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