Analog Electronics
A JFET has disadvantage of

  being noisy.
  having low input impedance.
  having small gain-bandwidth product.
  possessing positive temperature coefficient.

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Analog Electronics
Optocouplers combine

 Power transistor and silicon transistor.
  Infrared light emitting diode and a silicon photo transistor.
 IGBTs and MOSFETs.
 SITs and BJTs.

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