Transistors - JFETs

Image	Part Number	Description / PDF	Quantity	Rfq
	2N5115JTX02 Vishay / Siliconix	JFET P-CH 30V TO-18	0
	2N4858JTXV02 Vishay / Siliconix	JFET N-CH 40V 80MA TO-18	0
	2N4859JTXL02 Vishay / Siliconix	JFET N-CH 30V 360MW TO-18	0
	2N5115JTVL02 Vishay / Siliconix	JFET P-CH 30V TO-18	0
	2N5114JTVL02 Vishay / Siliconix	JFET P-CH 30V TO-206AA	0
	U291-E3 Vishay / Siliconix	JFET N-CH 30V 0.5W TO-206AC	0
	2N4858JTX02 Vishay / Siliconix	JFET N-CH 40V 80MA TO-18	0
	U290 Vishay / Siliconix	JFET N-CH 30V 0.5W TO-206AC	0
	2N4857JAN02 Vishay / Siliconix	JFET N-CH 40V 360MA TO-18	0
	2N4856JTXL02 Vishay / Siliconix	MOSFET N-CH 40V 50MA TO-18	0
	2N4857JTXV02 Vishay / Siliconix	JFET N-CH 40V 360MA TO-18	0
	2N4858JTVP02 Vishay / Siliconix	MOSFET JFET P-CH	0
	2N5114-E3 Vishay / Siliconix	JFET P-CH 30V TO-206AA	0
	2N4391-E3 Vishay / Siliconix	MOSFET N-CH 40V .1NA TO-18	0
	2N4339-2 Vishay / Siliconix	MOSFET N-CH 50V 1.5MA TO-206AA	0
	2N4393-E3 Vishay / Siliconix	MOSFET N-CH 40V .1NA TO-18	0
	2N5115JAN02 Vishay / Siliconix	JFET P-CH 30V TO-18	0
	2N4338-2 Vishay / Siliconix	MOSFET N-CH 50V 600UA TO-206AA	0
	2N4338 Vishay / Siliconix	MOSFET N-CH 50V 600UA TO-206AA	0
	2N4338-E3 Vishay / Siliconix	MOSFET N-CH 50V 600UA TO-206AA	0

Transistors - JFETs

1. Overview

Junction Field-Effect Transistors (JFETs) are three-terminal voltage-controlled semiconductor devices that regulate current flow through a conductive channel. As the first type of field-effect transistor, JFETs are characterized by high input impedance, low noise, and excellent analog signal handling capabilities. They play critical roles in modern electronics for signal amplification, switching, and impedance matching applications.

2. Main Types and Functional Classification

Type	Functional Features	Application Examples
N-channel JFET	Higher electron mobility, faster operation	Audio amplifiers, RF mixers
P-channel JFET	Complementary to N-channel, lower speed	Power switching, analog switches
Dual-gate JFET	Two control gates for improved linearity	TV tuners, communication systems
High-frequency JFET	Optimized for GHz-range performance	RF amplifiers, microwave circuits

3. Structure and Composition

JFETs consist of a semiconductor channel (typically silicon or GaAs) with source and drain contacts at each end. A reverse-biased p-n junction gate controls the channel width. Key structural elements include: - Channel: Determines current capacity and transconductance - Gate: Forms depletion region to modulate channel conductivity - Metallization layers: Provide low-resistance contacts - Passivation layer: Protects device surface from contamination

4. Key Technical Specifications

Parameter	Description	Importance
V_GS(off)	Gate-source cutoff voltage	Determines operating voltage range
I_DSS	Saturation drain current	Defines maximum current capability
g_m	Transconductance	Measures amplification efficiency
R_DS(on)	On-state resistance	Impacts power dissipation
f_T	Transition frequency	Limits high-frequency performance

5. Application Fields

Major industries utilizing JFETs include: - Audio equipment: Guitar amplifiers, microphone preamps - Test & measurement: Oscilloscopes, signal analyzers - Industrial control: Sensor interfaces, process control - Medical devices: ECG machines, diagnostic equipment - Communication systems: RF front-ends, satellite receivers

6. Leading Manufacturers and Products

Manufacturer	Representative Product	Key Features
TI (Texas Instruments)	J111	General-purpose N-channel JFET
ON Semiconductor	2N5457	High-voltage switching applications
Infineon Technologies	BF862	Low-noise RF amplifier JFET
STMicroelectronics	STJ105	Power JFET for industrial systems

7. Selection Guidelines

Consider the following factors when selecting JFETs: - Application type: Audio (low noise), switching (high I_DSS), or RF (high f_T) - Operating conditions: Temperature range, voltage requirements - Package type: Through-hole for prototyping vs. surface-mount for mass production - Cost vs performance: Balance between specifications and budget constraints

8. Industry Trends

Emerging trends shaping JFET development include: - Development of wide-bandgap JFETs using SiC/GaN for high-power applications - Integration with CMOS technology for mixed-signal systems - Miniaturization for portable electronics - Enhanced radiation-hardened variants for aerospace applications - Growing adoption in bio-sensing and IoT edge devices