A generic micromachined silicon platform for low-power, low-loss miniature transceivers

A generic micromachined silicon platform for low-power, low-loss miniature transceivers is described. This platform is fabricated by the dissolved wafer process and supports: 1) high self-resonant frequency and quality factor inductors suspended on a dielectric diaphragm, 2) low-loss polysilicon-metal capacitors, and 3) polysilicon resistors. The process uses a deep boron diffusion step to create silicon anchors which support a stress compensated dielectric diaphragm. The platform can be used to build miniature transmitters using either a hybrid-attached surface-mount transistor, or flip-chip bonded RF circuit. A Colpitts oscillator transmitter (5 mm×5 mm area) with a two turn dielectric suspended inductor was designed and fabricated using this technique. The transmitter oscillates in the frequency band of 275-375 MHz, consumes 200 μA, and has a transmission range of ~3 feet. The suspended coil has an inductance of 115 nH, a self-resonant frequency of >750 MHz and a Q of 22 at 275 MHz