Evaluation of Undesired Radio Waves Below −170 dBm/Hz From Semiconductor Switching Devices for Impact on Wireless Communications

The spread of undesired radio waves and the development of semiconductor switching devices causes serious noise interference in wireless communication systems. We introduce a system to evaluate the noise interference caused by such switching devices with high resolution. Our evaluation system consists of two parts: a high-resolution noise measurement system and an evaluation of wireless communication performance by system level simulations. The integrated power of undesired radio waves is measured within a 5-MHz bandwidth and can be detected even at an ultra-low power level of -177 dBm/Hz. The lower detection limit of the undesired radio waves is enough to evaluate the impact on wireless communication performance. We evaluated undesired radio waves from a wireless power transfer (WPT) system for charging electric vehicles. In our simulation, at the 840-MHz band, we observed an undesired radio waves level of -143 dBm/Hz near the WPT system that degraded the long-term evolution (LTE) sensitivity to -74 dBm/5 MHz.