A reconfigurable RF MEMS triple stub impedance matching network

This paper presents a reconligurable triple stub impedance matching network using RF MEMS technology centered at 10GHz. The device is capable of covering impedances on the whole Smith Chart. The device structure consists of three variable length stubs which are designed as distributed MEMS transmission lines and two lambda(g)/8 length CPW transmission fines connecting the stubs. The variable length stubs are implemented with 12 MEMS switches over CPW lines and CPW lines connecting the switches. lambda(g)/8 spacing between the stubs is selected to obtain a uniform distribution of the impedance points on the Smith Chart. Initial measurement results of the fabricated structure show a good agreement with the simulation results

Investigation of on-wafer TRL calibration accuracy dependence on transitions and probe positioning

This paper presents the effects of various transition types from the measurement plane to the reference plane in TRL calibration and probe positioning effects for on wafer measurements of CPW based devices. Fourteen different transition types, with direct, linear and exponential transitions, including 3 different variations of ground-signal-ground (GSG) spacing are examined. To observe the performance of the transitions, simple CPW transmission lines of different characteristic impedances are fabricated using standard lithography techniques on glass substrate and S-parameters are measured in 4.5-20 GHz band. Results are compared with electromagnetic simulations. The effects of probe misplacement along the lateral and horizontal axis are also investigated