A transistor is a three-layer semiconductor device, which may consist of a thin P-type layer sandwiched between two layers of N-type (as in the NPN transistor), or a thin layer of N-type material between two layers of P-type (as in the PNP transistor). It is used in circuits to amplify electrical signals or to perform as a switch to provide digital functions. 

Below are some of the transistors that we have: 

• Bipolar Transistors 
  Type: General Purpose, Power, Match Pair/Dual Amplifier and
  Quad 
  
  
• Field Effect Transistors 
  Type: General Purpose and TMOS Power 
  
  
• RF Transistors/Modules 
  
  
• SMD (Surface Mount Device) Transistors
  • MMBT3904, MMBT3906, MMBT4401, MMBT4403