Cmos - Mems Capacitor Having Large Tuning Range

Several CMOS-MEMS tunable capacitors have been designed, fabricated and tested. Large-tuning ranges and high Q values are achieved. The structures were made from the CMOS interconnect stack using a maskless CMOS micromachining process. The 1 generation capacitors were fabricated using Austria Microsystems (AMS) 0.6 μm and Agilent 0.5 μm CMOS process. These devices have a measured nominal capacitance of 209fF and a measured quality factor 28 at 1.5 GHz. The capacitance change is measured from 209fF to 294fF within a 24V control voltage, and 72.4 mW power at 1.5 GHz. 2-generation tunable capacitors in TSMC 0.35 μm CMOS process have larger tuning range and more power efficiency than the 1 generation designs. For these new designs, 3.52 to 1 tuning range has been measured with tuning from 42 fF to 148 fF within a 12 V control voltage, and 34mW power at 1.5 GHz. This recent design has a measured Q of 52 at 1.5 GHz. Electro-thermal actuation is used for all tunable capacitor designs. The essential differences between this work and prior work are the CMOS compatibility and using a maskless CMOS micromachining process.