Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
BCX53TX Nexperia	BCX53T/SOT89/MPT3	990
BCV71,215 Nexperia	TRANS NPN 60V 100MA TO236AB	83
PBSS5330XZ Nexperia	TRANS PNP 30V 3A SOT89	0
BCW69,215 Nexperia	TRANS PNP 45V 100MA TO236AB	21588
PBSS301NZ,135 Nexperia	NOW NEXPERIA PBSS301NZ - SMALL S	24435
BCX54-10,115 Nexperia	TRANS NPN 45V 1A SOT89	357
PBSS5480X,135 Nexperia	TRANS PNP 80V 4A SOT89	10103
PDTC144EU/HE115 Nexperia	SMALL SIGNAL BIPOLAR TRANSISTOR	205560
BCX51-10TF Nexperia	TRANS PNP 45V 1A SOT89	0
BCX51TF Nexperia	TRANS PNP 45V 1A SOT89	0
BC846BMB,315 Nexperia	TRANSISTOR NPN 65V 100MA SOT883	0
BCX54TF Nexperia	TRANS NPN 45V 1A SOT89	0
BC806-25VL Nexperia	BC806-25/SOT23/TO-236AB	9900
BCP53-16H,115 Nexperia	SMALL SIGNAL BIPOLAR TRANSISTOR	0
BCX54-16TF Nexperia	TRANS NPN 45V 1A SOT89	0
PMBT4403/DLT215 Nexperia	PNP SWITCHING TRANSISTOR	3604000
BCX54Z Nexperia	BIPOLAR DISCRETES	1000
BCX53-16TX Nexperia	BCX53-16T/SOT89/MPT3	0
PUMH13115 Nexperia	PUMH13 0.1A, 50V, 2-ELEMENT, N	0
BCX55-10TF Nexperia	TRANS NPN 60V 1A SOT89	0

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