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Transistors - Bipolar (BJT) - RF

Image Part Number Description / PDF Quantity Rfq
2N5109 PBFREE

2N5109 PBFREE

Central Semiconductor

RF TRANS NPN 20V 1.2GHZ TO39

0
UPA801T-A

UPA801T-A

CEL (California Eastern Laboratories)

RF TRANS 2 NPN 12V 4.5GHZ SOT363

0
BFP450E6433BTMA1

BFP450E6433BTMA1

IR (Infineon Technologies)

RF TRANS NPN 5V 24GHZ SOT343-4

0
2SC24040DL

2SC24040DL

Panasonic

RF TRANS NPN 20V 650MHZ MINI3-G1

0
AT-42086-TR1G

AT-42086-TR1G

Broadcom

RF TRANS NPN 12V 8GHZ 86 PLASTIC

0
NE97733-A

NE97733-A

CEL (California Eastern Laboratories)

RF TRANS PNP 12V 8.5GHZ SOT23

0
BFR94AW,115

BFR94AW,115

NXP Semiconductors

RF TRANS NPN 15V 5GHZ SOT323-3

0
NE68719-T1

NE68719-T1

CEL (California Eastern Laboratories)

RF TRANS NPN 3V 11GHZ 3SMINMOLD

0
BF494_D74Z

BF494_D74Z

Sanyo Semiconductor/ON Semiconductor

RF TRANS NPN 20V TO92-3

0
MRF8372GR2

MRF8372GR2

Microsemi

RF TRANS NPN 16V 870MHZ 8SO

0
BFR520T,115

BFR520T,115

NXP Semiconductors

RF TRANS NPN 15V 9GHZ SC75

0
BFG590/X,215

BFG590/X,215

NXP Semiconductors

RF TRANS NPN 15V 5GHZ SOT143B

0
CMPTH81 TR

CMPTH81 TR

Central Semiconductor

RF TRANS PNP 20V 600MHZ SOT23

0
JANTXV2N4957

JANTXV2N4957

Microsemi

RF TRANS PNP 30V 30MA TO72

0
2SC5338-AZ

2SC5338-AZ

CEL (California Eastern Laboratories)

RF TRANS NPN 12V 6GHZ SOT89

0
AT-41533-TR1G

AT-41533-TR1G

Broadcom

RF TRANS NPN 12V SOT23

0
BFS17W,135

BFS17W,135

NXP Semiconductors

RF TRANS NPN 15V 1.6GHZ SOT323-3

0
NE68139-T1

NE68139-T1

CEL (California Eastern Laboratories)

RF TRANS NPN 10V 9GHZ SOT143R

0
NE85633-T1B-A

NE85633-T1B-A

CEL (California Eastern Laboratories)

RF TRANS NPN 12V 7GHZ SOT23

0
BFG424F,115

BFG424F,115

NXP Semiconductors

RF TRANS NPN 4.5V 25GHZ 4SO

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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