Design and applications of high Q passive devices on multi-layered liquid crystalline polymer based substrates for handset applications

In the recent past, fully packaged RF modules suitable for integration in wireless handsets have been fabricated on organic packaging technology that uses a single sheet Liquid Crystalline Polymer (LCP) substrate. This paper demonstrates the RF characterization of inductors that were fabricated on two different stack-ups utilizing different configurations of the LCP substrate. The paper, then, shows the implementations of the embedded LC passives in RF front-end modules such as voltage controlled oscillators (VCOs) and tunable filters. The first application is the design and implementation of a 1.8 GHz feedback oscillator in a novel multi-layer laminate-type process technology that uses three layers of LCP substrate. The microstrip type oscillator measures a phase noise of -117 dBc/Hz at 100 KHz offset at 10 m W of power consumption. The oscillator meets the stringent phase noise specifications of cellular systems for both mobile-station and base-stations. The final application of the high quality factor (Q) passives is in the design and implementation of voltage tunable filters useful for WLAN applications. The filters were fabricated on a completely different stack-up that uses two layers of LCP substrate. The filter prototype is tunable from 1.75 to 2.03 GHz with an insertion loss of 2.5 dB using lossy surface-mount varactor diodes.