What are Small Signal Transistors?

Small Signal Transistors are transistors that are used to amplify low-level signals but can also can be used as a switch.

Typical hFE values for small signal transistors range from 10 to 500, with maximum Ic ratings from about 80 to 600mA.

They come in npn and pnp forms.

Maximum operating frequencies range from about 1 to 300 MHz.

As a design note, small signal transistors are used primarily when amplifying small signals, such as a few volts and only when using milliamperes of current. When using larger voltage and current (larger power), using many volts or amperes of current, a power transistor should be used.