Integrated circuit implementation of constant-charge biasing for capacitive RF MEMS switch

For the last two decades, Radio Frequency Microelectromechanical (RF MEMS) switches have drawn attention from RF/microwave community and have been extensively investigated due to their excellent RF performances. The reliability, however, is still one of the main issues to be improved for commercializing RF MEMS switches. A novel biasing scheme, constant-charge biasing, was introduced as a possible method for enhancing the reliability of capacitive RF MEMS switch. This work focuses on the implementation of integrated circuit (IC) for constant-charge biasing of a capacitive RF MEMS switch. After theoretical calculations, the design parameters of a switch were determined and the transient capacitance model of the switch was found. The IC was designed based on a charge-float-discharge method which is one of the realization methods of the constant-charge basing. The IC chip was fabricated with 0.8-mum High-Voltage Complementary Metal-Oxide-Semiconductor (CMOS) process through X-FAB foundry (Germany). The functional test results of the IC chip verified that the charge-float-discharge method was implemented in the circuit. The IC shows 1.2 mus rising time for 10 pF capacitance to 40 V.