High Precision Measurement of Transistor Noise with Automatic Calibration under Computer Control

The preliminary selection of transistors for use in low noise pre-amplifiers requires the measurement of the equivalent noise voltage under various operating conditions including the temperature. Available equipment often lacks the necessary precision and is difficult to calibrate, especially when the device temperature is varied. Suchi equipment requires skill andl patience from the operator. We describe a micro-computer controlled equipment which can measure transistor noise in the frequency range 10Hz to 100kHz to a greater accuracy than that previously obtainable. The transistor temperature and operating conditions may be scanned automatically over a wide range. Each measurement is internally calibrated.