An acoustic charge transport signal processing module featuring a low-temperature co-fireable ceramic chip carrier

Acoustic charge technology (ACT) has been integrated with digital control circuitry to achieve complex signal processing chips. The basic ACT device with the added digital circuitry calls for several different types of signals for operation including RF, DC, and digital control signals. Proper signal management is critical for minimizing direct-feed-through electromagnetic and common ground coupling. A low-temperature multilayer cofired technology is utilized in a chip carrier design that minimizes both types of coupling. Thick-film hybrid technology is used for the peripheral circuitry because it offers the ability to fabricate low-impedance vias to ground, low cost, and flexibility in assembly. The subassemblies are reflowed into a Kovar package. The package is hermetically sealed with fired-in glass troughs and a seam-welded lid. The direct-feed performance surpassed the product goals, with levels 50 dB below the delayed signal. Thermal characteristics of the package are acceptable, not limiting the temperature range of the completed module