Current Research Projects:
IV: High-Q Micromachined Resonators, Low-Loss Filters and Low Phase Noise Oscillator

Fig. 1: View of a micropacakged front-end for mm-wave frequencies (20-100 GHz). The filters, switches and high-Q oscillator can all be placed on the same wafer, together with the GaAs electronics. The entire thickness of the front-end is less than 1mm.

Fig. 2: Cross-section view of membrane suspended microstrip components.

Fig. 3: Micromachined 28 GHz resonator. The top wafer is removed for viewing purposed. A Q of 450-700 can be easily achieved at 20-80 GHz.

Fig. 4a: Micromachined 28 GHz 4-Pole Chebyshev filter. The top wafer is removed for viewing purposed.

Fig. 4b: Measured S-parameters of the 28 GHz filter. The insertion loss is only 0.9 dB including the silicon-to-membrane transitions. Notice than an isolation of better than 80 dB can be achieved on-wafer using micropackaging techniques.

Fig. 5a: Micromachined 60 GHz 4-pole Elliptic filter. The top wafer is removed for viewing purposed.

Fig. 5b: Measured S-parameters of the 60 GHz filter including the silicon-to-membrane transitions. The insertion loss is only 1.5 dB and is competitive with waveguide filters (insertion loss of 0.8-0.9 dB).

Fig. 6a: Micromachined 20 GHz 4-pole interdigital filter. The top afer is removed for viewing purposed.

Fig. 6b: Measured S-parameters of the 20 GHz filter. The resonators were not optimized for highest Q (see table above).

Fig. 7a: Micromachined diplexer for LMDS applications. See table above for specifications.

Fig. 7b: Measured S-parameters of the LMDS diplexer. The isolation between the transmit and receive ports is around 40 dB at 28 GHz and more than 50 dB at 31 GHz.

Fig. 8a: Picture of an oscillator at 28 GHz with a micromachined resonator Q of 460. The design follows the same as a Dielectric Resonator Oscillator (DRO).

Fig. 8b: Measured oscillation spectrum of the micromachined oscillator. (see table for details).