Bipolar transistors

What is the approximate transconductance gm of a bipolar transistor operating at a collector current of 1 mA? (Room temperature, thermal voltage VT ≈ 26 mV)

  1. AAbout 0.38 mS
  2. BAbout 38 mS
  3. CAbout 3.8 S
Show answer and explanation

Answer: B. About 38 mS

The transconductance of a bipolar transistor is gm = IC / VT: 1 mA ÷ 26 mV ≈ 0.038 S, or about 38 mS. At the same current, a bipolar transistor provides higher gm than a MOSFET.

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