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This paper presents a novel cost-effective microwave phase-shifter technology using thick-film ferroelectric varactors as the tuning component. The devices are fabricated by conventional screen-printing techniques with silver/platinum as the conducting layers and [Ba.sub.o.7][Sr.sub.o.3]Ti[O.sub.3] as the tunable dielectric layer. The microwave performance of the ferroelectric varactors is optimized in terms of both material process parameters and the varactor gate area dimensions. S-parameter measurements on a tunable reflective circuit are used to evaluate the performance of the varactor at around 2 GHz. The varactor parameters such as RF capacitance, tunability, and the Q factor of the varactor are studied as a function of the gate dimension. At 100-V dc-biasing voltage, the BSTO varactor loaded tunable reflective circuit exhibits a differential phase shift of 70[degrees] with a return loss of - 1.2 dB. This is equal to a figure-of-merit value of 58[degree]/dB. Full analog reflection-type and all-pass network phase shifters are also implemented in order to explore the monolithic integration of phase control devices into the RF system based on low-cost ceramic thick-film technology. Index Terms--Ferroelectric, phase shifter, screen printing, varactor.

A reliable printing encapsulating system (PES) having quality encapsulated components and no voids finds applications in advanced chip-on-board and multichip module devices. An epoxy resin used in PES has open lid storage properties and is viscous, facilitating mass production. The absence of voids makes the system thermal shock proof and resistant to moisture after short cure times.

Investigating the fabrication of MgB2 thick films on different substrates using a simple screen-printing method is discussed. It is concluded that the critical current densities are dependent only modestly on the external field.