Variable-length transmission lines for self-healing systems and reconfigurable millimeter-wave integrated circuits

This paper presents the design of a variable-length transmission line for millimeter-wave integrated circuits, giving design considerations and comparing different approaches. The implemented line consists of a stub that is connected to ground using 7 different switches, which can be used to change the electrical length of the line. Measurement results show that the equivalent inductance of the line can be tuned between 74.8 and 110 pH, which corresponds to 47% variation. In terms of electrical length, it can be tuned between 20.73° and 29.15°. The presented variable-length transmission line can be used in self-healing systems and reconfigurable devices, as well as to implement adjustable matching networks in load-pull measurement circuits.