If analog circuits (RF) and digital circuits (microcontrollers) work separately, they may work well on their own, but once they are placed on the same circuit board and powered by the same power source, the entire system is likely to become unstable. This is mainly due to the frequent oscillation of digital signals between ground and positive power supply (3 V in size), and the period is particularly short, often at the ns level. Due to their large amplitude and small switching time, these digital signals contain a large number of high-frequency components that are independent of the switching frequency. In the simulation part, the signal transmitted from the antenna tuning loop to the wireless device receiving part is generally less than 1 μ V. Therefore, the difference between digital signals and RF signals will reach 10-6 (120 dB). Obviously, if digital signals cannot be well separated from radio frequency signals, weak radio frequency signals may be damaged, which can deteriorate the performance of wireless devices and even render them completely inoperable.