Passive, lightweight thermal solutions for Remote Radio Head (RRH) electronics

The ever-increasing size of wireless networks has led to the development of new base station architectures. Traditional telecommunication base stations have baseband and radio-frequency (RF) components mounted inside an air-conditioned hut with co-axial cables transmitting signals to remote antennas. The industry is moving to distributed network and remote radio head (RRH) architectures where the baseband components are digitally connected to a group of RF components mounted on top of antenna towers. Operators who maintain these units typically desire a lightweight, low-volume passive thermal solution. Thermal issues are challenging with power amplifier (PA) powers ranging from 100-200 Watts. Traditional base station heat sinks that cool high-powered PA´s are made of a die-cast aluminum material having a low thermal conductivity. This paper introduces a unique two-phase heat spreader technology to improve the thermal performance of die-cast aluminum heat sinks used in RRH application. Experiments and CFD models were used to compare the thermal performance of baseline aluminum heat sinks to thermal solutions that included an embedded or directly-attach two-phase heat spreader. Results are presented that show a heat sink combined with a two-phase heat spreader solution can provide a 20% reduction in PA temperature or a 17% reduction in heat sink weight.