A logarithmic amplifier automatic test system base on GPIB interface

An automatic test system for logarithmic amplifier is presented, which is developed using GPIB interface based on Windows operating system and Visual Basic programming environment. With this system, parameters of logarithmic amplifiers, such as logarithmic dynamic range and logarithmic precision, can be automatically tested. Using an adaptive line fitting algorithm, both dynamic accuracy and dynamic range are improved. In this system, timers in VB are used to coordinate different peripheral devices for synchronous operation. The system has the advantage of high efficiency and small human error, thus greatly improving test efficiency, and it can satisfy the requirement of automatic test of logarithmic amplifiers with a log accuracy of plusmn 0.2 dB and a log dynamic range of 130 dB.