No-Calibration Relative Impedance and Mismatch Measurement Using Periodic Six Ports

A built-in self-test (BIST) technique based on periodic multiports is proposed. The periodic multiport theory is extended to show that symmetric unit cells can be used to find the ratio of two loads without calibration. Next, a novel test signal injection technique is used to measure conjugate matching between two loads without disrupting the system operation. Using the proposed method, periodic six ports are fabricated. Hardware experiments show that the proposed technique can measure conjugate matching between two loads with high accuracy from 2.2 to 3 GHz.