Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
ZTX550STZ Zetex Semiconductors (Diodes Inc.)	TRANS PNP 45V 1A E-LINE	697
BC640TA Sanyo Semiconductor/ON Semiconductor	TRANS PNP 80V 1A TO92-3	1298
TIP36CW STMicroelectronics	TRANS PNP 100V 25A TO-247	907
2SC1213C-E Renesas Electronics America	0.5A, 50V, NPN	3500
14-3459 NTE Electronics, Inc.	GLASS CLOTH TAPE-PLYGLASS 108 FT	12
BCP5416E6327HTSA1 IR (Infineon Technologies)	POWER BIPOLAR TRANSISTOR	4000
FJB3307DTM	POWER BIPOLAR TRANSISTOR	4800
2N5210	SMALL SIGNAL BIPOLAR TRANSTR NPN	24201
FJE3303H2TU Sanyo Semiconductor/ON Semiconductor	TRANS NPN 400V 1.5A TO126-3	191048000
BC817-25-7-F Zetex Semiconductors (Diodes Inc.)	TRANS NPN 45V 500MA SOT23-3	28177
MMBTA42-7-F Zetex Semiconductors (Diodes Inc.)	TRANS NPN 300V 0.5A SOT23-3	0
2SC4617EBTLP ROHM Semiconductor	TRANS NPN 50V 0.15A EMT3	0
MMBT3904 RFG TSC (Taiwan Semiconductor)	TRANSISTOR, NPN, 40V, 0.2A, 100A	10389
MMBT2222A-G Comchip Technology	TRANS NPN 40V 600MA SOT23	7319000
BCW61A IR (Infineon Technologies)	SMALL SIGNAL BIPOLAR TRANSISTOR	9000
BC54PA,115 Nexperia	TRANS NPN 45V 1A 3HUSON	1322
BST61,115 Nexperia	TRANS PNP DARL 60V 1A SOT89	1045
NTE179MP NTE Electronics, Inc.	TRANS PNP 40V 25A TO3	8
CPH6153-TL-E	BIP PNP 3A 20V	21000
MJD127T4G Sanyo Semiconductor/ON Semiconductor	TRANS PNP DARL 100V 8A DPAK	14365

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

Type	Functional Characteristics	Application Examples
NPN Transistor	Majority carriers: electrons. Requires positive base current for conduction.	Low-noise amplifiers, digital logic circuits
PNP Transistor	Majority carriers: holes. Conducts with negative base current.	Power supply circuits, motor controllers
High-Frequency BJT	Optimized for RF/microwave signal amplification (f_T > 100 MHz)	Wireless communication systems, radar
Power BJT	High current/voltage ratings (I_C > 1A, V_CE > 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

Parameter	Description	Importance
Current Gain (h_FE)	Ratio of collector to base current (10-1000)	Determines amplification capability
Transition Frequency (f_T)	Frequency at which current gain drops to 1	Limits high-frequency performance
Max Collector Current (I_Cmax)	Maximum allowable continuous collector current	Defines power handling capability
Breakdown Voltage (V_CEO)	Max voltage between collector and emitter	Prevents device failure under stress
Saturation Voltage (V_CEsat)	Voltage drop in fully conducting state	Affects 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

Manufacturer	Product Series	Key Specifications	Typical Use
ON Semiconductor	2N3904	hFE: 100-300, fT: 300 MHz	General-purpose switching
Infineon	BC547	VCEO: 50V, ICmax: 100mA	Analog signal amplification
STMicroelectronics	2SD2656	ICmax: 15A, VCEO: 80V	Power inverter applications
Diodes Inc.	BFR93A	fT: 10 GHz, Noise Figure: 2dB	High-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=V_CE I_C)
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