High density overlay interconnect (HDI) delivers high frequency performance for GaAs systems

The authors point out that large die size, high gate and transistor count digital GaAs devices present problems to the system designer, such as efficient distribution of low voltage, high current power supply bias (2 VDC at 25 A, and greater). The effective delivery of such electrical power must also allow for efficient removal of the heat generated by the electronics circuits. By exploiting appropriate MCM technology, these thermal concerns are satisfied while eliminating to a maximum extent conventional circuit packaging parasitics which limit performance of high frequency systems. The overlay interconnect MCM approach used by GE/TI places IC chips first, into a structure for the most advantageous thermal management, while eliminating conventional packaging resistance, inductance and capacitance effects. Several designs constructed with overlay interconnect demonstrate the highest frequency operation and thermal performance of MCMs to date. System designs with 400 MHz and greater clock operation and dissipating 50 W are described