-This paper describes the realization of compact 360 degree phase-shifter MMICs using thin-film BST varactors in a series cascade of all-pass networks. Unlike conventional delayline structures, all-pass networks provide constant phase shift with small variation of insertion loss. In similar fashion, very broadband phase-shifters can be implemented by cascading allpass networks with staggered center-frequencies. Using a thinfilm BST technology for the varactors, extremely compact and low-cost phase-shifter structures have been developed. Selected results are shown in the 1-30GHz range.

This paper describes the design and characterization of a lumped-element tunable IF filter using thinfilm barium strontium titanate (BST) varactors. The filter was designed to operate from 30-88MHz in three separate switchselectable bands with a 0-12V DC control voltage. A relatively constant insertion loss of <5dB was obtained over the desired tuning range.The circuit was also characterized over temperature from -40°C to +80°C, showing relatively little change in insertion loss over temperature, but a slight reduction in tuning range at elevated temperatures.

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