Design of Broadband Matching Method for Square-law Detection Circuit of Microwave Imaging

Presents a broadband matching circuit designs for a square-law detector with a bandwidth of 2GHz to 6GHz, which is used to solve the problem of correlation circle distortion. The problem is caused by the mismatching of the input impedance of the detector in a microwave imaging system with a bandwidth of 4GHz. The matching process starts from the theoretical analysis of Smith circle graph and impedance matching. LTC5535 chip, ADS (Advanced Design System) software, and Smith Chart tool are used to simulate and optimize the schematic diagram of a broadband square-law detector. The ideal component is replaced by the component in Murata library to complete layout design and joint simulation. The simulation results show that the broadband square-law detector has good impedance matching within the operating frequency range, and the input insertion loss is less than −10dB, which has certain practical value.