A miniaturized three-stage combline multilayer bandpass filter having five transmission zeros is proposed. The filter is implemented in a novel semi-distributed stripline configuration using LTCC technology that occupies an area of (2.00 x 1.25 x 0.50) mm3. A distinct feature of this filter is the independent creation and control of the upper band transmission zeros to improve the skirt characteristics. Measured samples show a maximum of 1.5 dB insertion loss in the pass band with a center frequency at 5.5 GHz and a 3dB bandwidth of 20%. The BPF has 40 dB and 20 dB of attenuation at 4.0 GHz and 7.2 GHz respectively, making it a desirable candidate for Wireless LAN applications.

Thin film passives facilitate the design of reduced size components required for consumer wireless products when compared to current PCB or LTCC solutions. This paper describes the development of a lowloss, thin film process and subsequent fabrication of a WLAN antenna switch module. Parts were fabricated using both a typical Au based MMIC process and a reduced RF loss Cu process. Inductor Q was doubled and loss reduced by about .3 -.4 dB for Tx and Rx channels by using the low-loss Cu process.

A study of the diffusion of zinc into Ga1−xAlxAs with a ‘‘leaky tube’’ diffusion furnace has been carried out. The Ga1−xAlxAs epitaxial layers were grown with liquid phase epitaxy, and the aluminum concentration was varied from 0 to 44% in 4% increments; diffusions were performed in the temperature range 550–650 °C. It was found that the junction depth versus aluminum concentration was not a simple, monotonically increasing curve; rather, dramatic decreases in the apparent diffusion coefficient at xAl≊0.05 and xAl≊0.20 suggest that point defects, possibly including the DX center, are playing a significant role.

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