RF responses of non-linear devices to induce the faulty operation of electronic apparatus for electromagnetic waves

摘要

It has been reported that radio-frequency (RF) electromagnetic waves can cause the faulty operation of electronic apparatus. We investigated the cause of the faulty operation of an electric wheelchair, and concluded that RF electromagnetic waves induced abnormal responses of the operational (OP) amplifiers and diodes being used in the control circuit, which made the DC output voltages change, leading to the faulty operation. In this paper, we examined experimentally the responses to RF electromagnetic waves of non-linear devices commonly used in the control unit of electric wheelchairs. We observed the output waveforms of the diode and OP amplifier for RF sinusoidal signals with respect to the frequency and amplitude. The RF responses of transistors constructing the OP amplifier were also examined in order to investigate the change cause of the output voltage of the OP amplifier. As a result, we found that the change of the DC output voltages due to RF electromagnetic waves is caused by the rectification and smoothing effects of non-linear devices.