A 4-18-GHz reconfigurable RF MEMS matching network for power amplifier applications

We have developed a novel reconfigurable matching network based on the loaded-line technique. The network is composed of N-switched capacitors (N = 4-8) with a capacitance ratio of 4-5:1 and is suitable for power amplifiers at 4-18 GHz, or as an impedance tuner for noise parameter and load-pull measurements at 10-28 GHz. The networks are very small, and offer better performance than double or triple stub matching networks. Extensive loss analysis indicates that the 8-element network has. a loss of 0.5 dB at 4-12 GHz, and less than 1.5 dB at 18 GHz, even when matching a 10Omega output impedance to a 50Omega load. As expected, the 4-element matching network has about half the loss of the 8-element network, but with much less impedance coverage. Both networks were simulated and measured in high VSWR conditions and can handle at least 500 mW of RF power at 4-18 GHz. The application areas are in phased array antennas, reconfigurable power amplifiers, and wideband noise-parameter and load-pull measurement systems. (C) 2004 Wiley Periodicals, Inc.