A GSM/EDGE/WCDMA Adaptive Series-LC Matching Network Using RF-MEMS Switches

• Published in: IEEE journal of solid-state circuits 2008-10, Vol.43 (10), p.2259-2268
• Main Authors: van Bezooijen, A., de Jongh, M.A., Chanlo, C., Ruijs, L., van Straten, F., Mahmoudi, R., van Roermund, A.
• Format: Article
• Language: English
• Subjects: Adaptive filters; Adaptive systems; Applied sciences; Arrays; Circuit properties; Circuits; Dielectric losses; Dielectric, amorphous and glass solid devices; Distortion measurement; Electric potential; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; GSM; Impedance; impedance matching; Matching; Micro- and nanoelectromechanical devices (mems/nems); micro-electromechanical devices; Mobile handsets; Modules; Multiaccess communication; phase detection; power amplifiers; Radiofrequency microelectromechanical systems; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; switched capacitor filters; Switches; Switching, multiplexing, switched capacity circuits; Theoretical study. Circuits analysis and design; Tuning; Voltage
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2008.2004334

To preserve link quality of mobile phones, under fluctuating user conditions, an adaptively controlled series-LC matching circuit is presented for multi-band and multi-mode operation. Following a bottom-up approach, we discuss the design of an RF-MEMS unit cell for the construction of a 5-bit switched capacitor array. To reduce dielectric charging of the RF-MEMS devices their average biasing voltage is minimized by applying a bipolar waveform with a small high/low duty-cycle obtained from a high-voltage driver IC. RF-MEMS capacitive switches are applied because of their high linearity, low loss, large tuning range, and easy control in the discrete domain. Application specific RF-MEMS pull-in and pull-out voltage requirements are derived. An impedance phase detector is used to feed mismatch information to an up-down counter providing robust iterative control. The measured MEMS array capacitance tuning ratio is almost a factor 10. Module insertion loss is 0.5 dB at low-band and high-band. Harmonic distortion is less than -85 dBc at 35 dBm output power and the EVM, measured in EDGE-mode, is less than 1% at 27 dBm . The adaptively controlled module, connected to a planar inverted-F antenna, shows desired impedance correction. For extreme hand-effects the maximum module impedance correction at 900 MHz is -75jOmega.