The 2N3906 is a commonly used PNP bipolar junction transistor intended for general purpose low-power amplifying or switching applications. It is designed for low electric current and power and medium voltage, and can operate at moderately high speeds.

The 2N3906 is manufactured in a plastic TO-92 case. When looking at the flat side with the leads pointed downward, the three leads emerging from the transistor are, from left to right, the emitter, base, and collector leads.

The 2N3906 is specified by a collector current of 200 mA, collector-base and collector-emitter voltages of 40 V, for power dissipation of 300 mW. Its current gain bandwidth product Ft is 250 MHz, with a beta of at least 100.

The complementary NPN transistor to the 2N3906 is the 2N3904. Both types were registered by Motorola Semiconductor in the mid-1960s.