How to Perform DC Current Gain Testing on Bipolar Junction Transistors with a Two-channel SMU

A bipolar junction transistor (BJT) is a three-terminal transistor characterized by its ability to use a small amount of current injected at one terminal to control larger currents between the remaining two terminals. This characteristic makes BJTs ideal for amplifier applications.

Some applications, particularly those surrounding amplifiers used in audio systems, wireless communication, or industrial automation, may require “matched” transistors. Transistor matching guarantees that two or more transistors in a circuit will behave identically, which is crucial for minimizing DC offsets and distortions and improving reliability and performance.

Transistor matching goes beyond simply using two transistors of the same type from the same manufacturer, as their behavior may differ due to variances within the device’s specified tolerances. To guarantee that the transistors are matched, we will need to measure and compare each transistor’s DC Current Gain (hFE), which is a commonly used criteria for matching.

This application note discusses how the KickStart Software IV Characterizer App provides a simple and reliable way to measure BJT DC current gain (hFE) for device evaluation and matching.