Advantages of HBT Transistor | disadvantages of HBT Transistor
This page covers advantages and disadvantages of HBT Transistor. It mentions HBT Transistor advantages or benefits and HBT Transistor disadvantages or drawbacks.
What is HBT Transistor?
As we know Bipolar Junction Transistors are made either using homo-junctions or using hetero-junctions. In homojunction transistors, same materials are joined together such as silicon to silicon. In heterojunction transistors, different materials are joined together such as Ge (Germanium) to GaAs (Gallium Arsenide). Homojunction transistor acts similar to traditional BJT.
AlGaAs and GaAs are used as materials for the construction of heterojunction BJT.
The figure-1 depicts cross section of HBT with different layers used in its construction.
Refer difference between HBT vs HEMT transistor types>>.
Benefits or advantages of HBT Transistor
Following are the benefits or advantages of HBT Transistor:
➨It offers low base resistance and low forward transit time due to much higher base doping.
➨Due to above, it offers higher cut-off frequency.
➨It offers very low collector to substrate capacitance due to semi-insulating GaAs substrate.
➨Higher efficiency can be achieved as small base voltage variation can also turn off the HBT device completely.
➨It offers wideband impedance matching.
➨It has lower cost and delivers higher efficiency.
Drawbacks or disadvantages of HBT Transistor
Following are the disadvantages of HBT Transistor:
➨The disadvantages of HBT varies based on materials used for its construction. For example, InP HBTs are brittle and expensive substrate. InP HBT is immature technology compare to GaAs HBT.
➨Si and SiGe based HBTs offer low breakdown voltage.