Transistors - JFETs

Image	Part Number	Description / PDF	Quantity	Rfq
	DSK9J01Q0L ROHM Semiconductor	TRANS JFET N-CH 30MA SMD	0
	CP548-2N5116-CT Central Semiconductor	JFET P-CH 30V 50MA	0
	2N5546JTXL01 Vishay / Siliconix	JFET N-CH 50V TO-71	0
	J3D016YXU/T1AY599J NXP Semiconductors	TRANSISTOR JFET	0
	J5C145MU0/T0BC7DUP NXP Semiconductors	TRANSISTOR JFET	0
	U291 Vishay / Siliconix	JFET N-CH 30V 0.5W TO-206AC	0
	2N5433-E3 Vishay / Siliconix	JFET N-CH 25V 0.3W TO-52	0
	J3D016YXV/T1AY599J NXP Semiconductors	TRANSISTOR JFET	0
	2N5116UB Roving Networks / Microchip Technology	P CHANNEL JFET	0
	2N4856JTXV02 Vishay / Siliconix	MOSFET N-CH 40V 50MA TO-18	0
	2N4857JTX02 Vishay / Siliconix	JFET N-CH 40V 360MA TO-18	0
	2N5545JTXL01 Vishay / Siliconix	JFET N-CH 50V TO-71	0
	2N4861JTX02 Vishay / Siliconix	JFET N-CH 30V TO-206	0
	2N4392-2 Vishay / Siliconix	MOSFET N-CH 40V .1NA TO-18	0
	U430 Vishay / Siliconix	JFET P-CH 25V TO-78	0
	J3A040YXS/T0BY4571 NXP Semiconductors	TRANSISTOR JFET 8PLLCC	0
	2N4859JAN02 Vishay / Siliconix	JFET N-CH 30V 360MW TO-18	0
	J2A012YXZ/S1AY73AJ NXP Semiconductors	TRANSISTOR JFET	0
	5185_2N4391 Sanyo Semiconductor/ON Semiconductor	MOSFET N-CH JFET	0
	J3D081YXV/T1AY5E4J NXP Semiconductors	TRANSISTOR JFET	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