The growing number of RF, microwave, and millimeter-wave applications has led to a growth in the number of RF transistor types, semiconductors, and configurations being used today. Future developments on these technologies are also ongoing, as competition in wireless communications, satellite communications, radar, sensing, test and measurement, and other applications grows. As more devices used RF/wireless technology to communicate and sense, there will be an even greater diversity of RF transistor technologies. Some of the RF transistor types, configurations, and semiconductors have been in use for decades, and are often still used in certain niche applications, while other nuances of RF transistor technology have recently reached the market and are enabling new applications.
In essence, there are three categories of RF semiconductor technologies, small-signal, switching, and power transistors. Certain RF transistor types and semiconductor configurations are best suited to certain applications, which is why there is such a diversity of configurations. Small-signal technologies are typically used for low-noise signal processing and amplification, where power transistors are used for high-gain and high power applications. Switching transistors are used for their ability to rapidly be set to conduction-/off-states with minimal transient performance degraded factors. As most RF transistors are used to make amplifiers, there are three main categories of amplifiers, low-noise amplifiers, gain block amplifiers, and high power amplifiers.
RF Transistor Types
• Bipolar Junction Transistor (BJT)
• Heterojunction Bipolar Transistor (HBT)
• Insulated-gate Bipolar Transistor (IGBT)
• High Electron Mobility Transistor (HEMT)
• Pseudomorphic HEMT (pHEMT)
• Enhancement Mode pHEMT (E-pHEMT)
• Field Effect Transistor (FET)
• Junction Gate Field Effect Transistor (JFET)
• Metal Oxide Semiconductor FET (MOSFET)
• Metal-Semiconductor FET (MESFET)
• Linear Diffusion MOSFET (LDMOS)
• Vertical Double Diffused MOSFET (VDMOS)
• Si Bipolar COmplementary Metal Oxide Semiconductor (Si BiCMOS)
RF Transistor Semiconductors
• Silicon (Si)
• Silicon-on-insulator (SoI)
• Silicon Carbide (SiC)
• Indium Phosphide (InP), Indium Aluminum Arsenide (InAlAs), or Indium Gallium Arsenide (InGaAs)
• Gallium Arsenide (GaAs) or Aluminum GaAs (AlGaAs)
• Gallium Nitride (GaN) or Aluminum GaN (AlGaN)
• Silicon Germanium (SiGe)
| Table: Common Semiconductor Properties | ||||||||
| Material | Bandgap
(eV) ~300K |
Saturated Electron Velocity (x10^7 cm/s) | Electron Mobility (cm2/Vs) | Critical Field Ec
(V/cm) |
Thermal Conductivity
(W/m·K) |
Coefficient of Thermal Expansion (ppm/K) | Power Device Figure of Merit
(u_n*E_c^3) |
Dielectric Constant
(epsilon_r) |
| InSb | 0.17, D | – | 77,000 | 1,000 | 18 | 5.37 | – | – |
| InAs | 0.354, D | – | 44,000 | 40,000 | 27 | 4.52 | – | – |
| GaSb | 0.726, D | – | 3,000 | 50,000 | 32 | 7.75 | – | – |
| InP | 1.344, D | 1 | 5,400 | 500,000 | 68 | 4.6 | – | 12.5 |
| GaAs | 1.424, D | 1 | 8500 | 400,000 | 55 | 5.73 | 20 | 12.8 |
| GaN
(AlGaN/GaN) |
3.44, D | 1.5 | 900-2000 | 3,000,000 | 110
(200 Film) |
5.4-7.2 | 3000 | 9 |
| Ge | 0.661, I | – | 3,900 | 100,000 | 58 | 5.9 | – | |
| Si | 1.12, I | 1 | 1,400 | 300,000 | 130 | 2.6 | 1 | 11.8 |
| GaP | 2.26, I | – | 250 | 1,000,000 | 110 | 4.65 | – | – |
| SiC (3C, b) | 2.36, I | ~2 | 300-900 | 1,300,000 | 700 | 2.77 | – | – |
| SiC (6H, a) | 2.86, I | ~2 | 330 – 400 | 2,400,000 | 700 | 5.12 | – | – |
| SiC (4H, a) | 3.25, I | ~2 | 700 | 3,180,000 | 700 | 5.12 | 675 | 10 |
| C (diamond) | 5.46-5.6, I | – | 2,200 | 6,000,000 | 1,300 | 0.8 | – | – |
Common RF Transistor Configurations
• GaN (AlGaN/GaN)
> GaN on GaN
> GaN on Diamond
> GaN on Si
> GaN on SiC
> GaN HEMT
• GaAs
> GaAs FET
> GaAs IGBT
> GaAs MESFET
> AlGaAs/GaAs HEMT
> GaAs pHEMT
• InP
> InP HEMT
> InP HBT
• SiC
> SiC MESFET
> SiC MOSFET
• SiGe
> SiGe HBT
> SiGe/SiC (SiGe:C)
• Si
> Si MOSFET
> Si LDMOS
> Si VDMOS
> Si BJT (Si-Bipolar)
> SoI
> Sapphire-on-Silicon (Ultra CMOS)
> Si BiCMOS
Learn more about Pasternack’s expansive line of RF, microwave, and millimeter-wave amplifiers here.
