A Watt-level, Thermally Reliable Ku-band SiGe HBT Cascode Flip-Chip Power Amplifier Module Using an Optimal IC-to-Package ElectroThermal Codesign for LEO SATCOM Transmit Front-End

This work presents a compact, Watt-level SiGe HBT flip-chip power amplifier module (PAM) for emerging low earth orbit (LEO) SATCOM transmitter (TX) front-end. To attain high power yet thermal ruggedness, two differential SiGe HBT cascodes are combined through a four-way transformer balun, with so-called IC-to-Package ElectroThermal (ETH) codesign. Optimal layout of the PA output stage, copper pillar (CuP) bumps, and a laminate interposer are combined in ETH codesign, which decreases thermal resistance (RTH) of PAM by 14.8%, and it is verified through both thermal simulation and measurement. Fabricated in 0.13 μm SiGe BiCMOS, measured saturated output power (PSAT) and peak PAE of the thermally optimized Ku-band SiGe PAM are 28.7 dBm and 36.8% at 10.7 GHz, respectively, and remain 28.2 dBm and 34.8% at Tamb = 85°. The proposed ETH codesign enables the first success of delivering products to rapidly expanding Ku-band SATCOM user terminal market.