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Transistors - Bipolar (BJT) - RF

Image Part Number Description / PDF Quantity Rfq
MRF581

MRF581

Microsemi

RF TRANS NPN 18V 5GHZ MICRO X

0
LM3046M

LM3046M

Texas Instruments

RF TRANS 5 NPN 15V 14SOIC

0
NE97833-T1B-A

NE97833-T1B-A

CEL (California Eastern Laboratories)

RF TRANS PNP 12V 5.5GHZ SOT23

0
HFA3127R96

HFA3127R96

Intersil (Renesas Electronics America)

RF TRANS 5 NPN 12V 8GHZ 16QFN

0
2SC4228-A

2SC4228-A

CEL (California Eastern Laboratories)

RF TRANS NPN 10V 8GHZ SC70-3

0
KSC1393RBU

KSC1393RBU

Sanyo Semiconductor/ON Semiconductor

RF TRANS NPN 30V 700MHZ TO92-3

0
AT-64020

AT-64020

Broadcom

RF TRANS NPN 20V 200SMD

0
HFA3128R96

HFA3128R96

Intersil (Renesas Electronics America)

RF TRANS 5 PNP 15V 5.5GHZ 16QFN

0
FMMTH10TC

FMMTH10TC

Zetex Semiconductors (Diodes Inc.)

RF TRANS NPN 25V 650MHZ SOT23-3

0
NE85634-A

NE85634-A

CEL (California Eastern Laboratories)

RF TRANS NPN 12V 6.5GHZ SOT89

0
AT-32032-TR2G

AT-32032-TR2G

Broadcom

RF TRANS NPN 5.5V SC70-3

0
2N3866 TIN/LEAD

2N3866 TIN/LEAD

Central Semiconductor

RF TRANS NPN 30V 500MHZ TO39

0
2SC4536-T1-AZ

2SC4536-T1-AZ

CEL (California Eastern Laboratories)

RF TRANS NPN 15V 5.5GHZ SOT89

0
2SC5006-T1-A

2SC5006-T1-A

CEL (California Eastern Laboratories)

RF TRANS NPN 12V 4.5GHZ SOT523

0
AT-32063-TR1G

AT-32063-TR1G

Broadcom

RF TRANS 2 NPN 5.5V SOT363

0
MAPR-002731-115M00

MAPR-002731-115M00

Metelics (MACOM Technology Solutions)

RF TRANS NPN 65V

0
MPSH10_D27Z

MPSH10_D27Z

Sanyo Semiconductor/ON Semiconductor

RF TRANS NPN 25V 650MHZ TO92-3

0
2N5770

2N5770

Sanyo Semiconductor/ON Semiconductor

RF TRANS NPN 15V TO92-3

0
BFP620E7764BTSA1

BFP620E7764BTSA1

IR (Infineon Technologies)

RF TRANS NPN 2.8V 65GHZ SOT343-4

0
MRF321

MRF321

Metelics (MACOM Technology Solutions)

RF TRANS NPN 33V 244-04

0

Transistors - Bipolar (BJT) - RF

1. Overview

Radio Frequency Bipolar Junction Transistors (RF BJTs) are three-layer semiconductor devices optimized for amplification and switching in high-frequency applications (typically >100 MHz). These transistors maintain stable performance in microwave and ultra-high frequency (UHF) ranges, characterized by high current gain-bandwidth product (fT), low noise figures, and fast switching capabilities. Their importance in modern technology spans wireless communication infrastructure, radar systems, and RF test equipment, enabling efficient signal transmission and reception in 5G networks, satellite communications, and IoT devices.

2. Main Types & Functional Classification

TypeFunctional FeaturesApplication Examples
NPN RF BJTHigh electron mobility, optimized for low-noise amplification5G base station LNAs, GPS receivers
PNP RF BJTComplementary design for power amplificationRF power modules, automotive radar
RF Darlington PairHigh (current gain), cascaded amplificationAntenna drivers, industrial RF heaters
Heterojunction Bipolar Transistor (HBT)Compound semiconductor materials (SiGe/GaAs), ultra-high fTOptical communication transceivers, mmWave systems

3. Structure & Composition

Typical RF BJT structure includes:

  • Material: Silicon (Si), Silicon-Germanium (SiGe), Gallium Arsenide (GaAs)
  • Layer Architecture: Emitter (high doping), Base (thin layer), Collector (graded doping)
  • Package Types: Surface-mount (SOT-89, SOT-343), Through-hole (TO-18, TO-92)
  • Metallization: Gold/aluminum contacts for reduced parasitic resistance

Advanced designs incorporate air-bridge structures to minimize parasitic capacitance and epitaxial layers for improved frequency response.

4. Key Technical Parameters

ParameterDescriptionTypical Range
fT (Transition Frequency)Current gain cutoff frequency1 GHz - 100 GHz
GUM (Max. Available Gain)Power gain at optimal impedance10 dB - 30 dB
Pout (Output Power)RMS power capability0.1 W - 500 W
NF (Noise Figure)Signal-to-noise degradation0.3 dB - 5 dB
VCE0 (Breakdown Voltage)Collector-emitter withstand voltage5 V - 80 V
(Junction Temperature)Thermal stability limit150 C - 200 C

5. Application Fields

  • Telecommunications: 5G massive MIMO amplifiers, fiber optic transceivers
  • Defense: Phased array radar systems, electronic warfare jammers
  • Test & Measurement: RF signal generators, spectrum analyzers
  • Consumer Electronics: Bluetooth LE modules, Wi-Fi 6E front-ends
  • Industrial: Plasma generators, RFID readers

6. Leading Manufacturers & Products

ManufacturerRepresentative ProductKey Specifications
Infineon TechnologiesBFP740FfT=50 GHz, NF=0.8 dB, Pout=18 dBm
STMicroelectronicsSTAG21412.7 GHz dual-stage amplifier, 32 dB gain
Skyworks SolutionsASK240110.05-6 GHz, 50 W GaAs power transistor
ON SemiconductorMRF151G125 W, 880 MHz, 40% efficiency

7. Selection Guidelines

Key considerations:

  1. Match fT to application frequency with 20% margin
  2. Verify load-line requirements for power applications
  3. Select appropriate package for thermal dissipation (e.g., TO-220 for >50 W)
  4. Derate VCE0 by 30% in high-temperature environments
  5. Consider integrated solutions (RFICs) for complex impedance matching

8. Industry Trends

Future development directions:

  • Transition to SiGe BiCMOS technology for 100+ GHz applications
  • Integration with GaN-on-SiC substrates for hybrid power amplifiers
  • Development of 5G NR direct-conversion transmitters using HBT arrays
  • Advancements in wafer-level packaging (WLP) for mmWave 5G devices
  • Adoption of AI-driven parameter optimization in production testing
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