Bipolar transistors

Which circuit uses two matched transistors to make the current in one transistor equal to the current in the other?

  1. ADarlington circuit
  2. BBridge rectifier
  3. CCurrent mirror
Show answer and explanation

Answer: C. Current mirror

A current mirror copies the current flowing in a reference transistor into another transistor, as if reflecting it in a mirror. It is widely used in analog ICs to supply bias currents to amplifiers and as an active load. It can be built with MOSFETs as well.

Practice this topic Back to topic

More Bipolar transistors questions

  1. What does a differential pair, with the emitters of two transistors connected to a common current source, do?
  2. 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)
  3. What is the main use of a photocoupler, which combines an LED and a phototransistor in one package?
  4. What is the main reason for using a current-feedback bias circuit with an emitter resistor in a transistor amplifier?
  5. In an amplifier, what is the DC voltage and current state of the transistor with no input signal called?