Abstract:In order to solve the problem of "signal reflection" in the communication circuit, this paper designs a reflectionless notch filter to "absorb" the microwave signal at a specific frequency point , and improved the stopband performance and absorption efficiency of the existing reflectionless low-pass filter by cascating reflectionless notch filter. Using the GaAs IPD process to design the layout, the layout size of the devices is only 800um*500um*87.71um, 1500um*500um*87.71um. The layout simulation results show that the reflectionless notch filter can effectively absorb microwave signals in specific frequency, the average absorption efficiency of more than 90%. The improved reflectionless low-pass filter has a good stopband performance, and the insertion loss of less than 2.5dB in the DC-3.5GHz frequency band, the insertion loss of 20dB at 1.4 times the cutoff frequency and the insertion loss of 40dB at 1.7 times the cutoff frequency. In terms of stopband signal absorption, within the frequency range of DC-7.5GHz, the return loss of the filter is always greater than 15dB, and the absorption efficiency of the reflected signal is more than 95%.