Research And Design Of High Power Electrically Adjustable Attenuator For Radiation Interference Cancellation System

With the rapid development of science and technology,electronic equipment is widely used in all walks of life.At the same time,it also causes a large number of electronic equipment to gather in a limited space.They are close to each other and will cause certain interference between each other.When the transmission power of the device is large,other devices may not work properly.Therefore,the research on adaptive interference cancellation technology has been put on the agenda.As a new effective way to solve the problem of electromagnetic interference,it is an important research topic for scholars at home and abroad.As an important active control device in the adaptive interference cancellation system,the ESC attenuator directly affects whether the entire interference cancellation system meets the standard.The electrically adjustable attenuator designed in this paper is mainly used in the radiation interference cancellation system with an operating frequency of 1MHz to 30 MHz.In order to make the performance of the electrically adjustable attenuator meet requirements of the radiated interference cancellation system,the transmission line transformer,Attenuation network and control part make more detailed analysis and design,the specific work content is as follows.First,the PIN diode is combined with the transmission line transformer to form a special transmission line transformer structure.This transmission line transformer can realize the gating of the two outputs of the electrically adjustable attenuator by controlling the positive and negative of the external DC bias.When the bias voltage is positive,the positive output terminal is turned on,and when the bias voltage is negative,the reverse output terminal is turned on,and the phase difference between the forward output signal and the reverse output signal is 180 degrees.Secondly,using the characteristic that the PIN diode current is inversely proportional to the resistance,an attenuation network that meets the requirements of this paper is designed and simulated on the ADS RF simulation software.The simulation results show that within the operating band of 1MHz to 30 MHz,the ESC attenuator can achieve an attenuation dynamic range of 5d B to 70 d B,and in the entire attenuation range,the attenuation flatness is less than 0.5d B,and the voltage standing wave ratio is less than 1.2,the power capacity can reach 2W.Finally,in order to reduce the number of external bias voltages,only one DC bias is used,which realizes the control of the two circuits of the voltage driving circuit and the attenuator driving circuit,simplifying the circuit of the control part.The schematic diagram of the high-power electrically adjustable attenuator of the radiation interference cancellation system was drawn on Altium Designer,and the PCB was generated.