A BIST procedure for analog mixers in software radio

Describes a technique for testing mixers with digital adaptive filters. RF circuits are widely used in data transmission applications, such as wireless communication, radio and portable phone systems. However, traditional analog BIST covers mainly linear circuits, being unsuitable for nonlinear pieces of hardware like analog mixers. Herein, an adaptive nonlinear filter is trained so that it can mimic the behavior of a mixer. Then, a test stimulus is simultaneously applied to the filter and the mixer. The outputs of both circuits are then compared to check whether the circuit under test is faulty or fault free. A prototype of a mixer was built in order to allow fault injection in the circuit under test. Thus, the detection capability of the proposed technique could be checked in a real life circuit. The preliminary results point to a very promising test technique. The test procedure is very precise, low cost and allows a complete fault coverage with a very small testing time.