Impact of microfluidic cooling on high power amplifier RF performance

This paper presents the results of an experimental investigation into the impact of microfluidic cooling on the performance of high power Gallium Nitride (GaN) amplifiers (HPAs). Electrical and thermal measurements were taken on a high frequency, broadband HPA, cooled using two different thermal management techniques; “conventional” (or remote) cooling where the chip is separated from its heat sink by several packaging materials, and a newly developed “embedded” microfluidic cooling technique where the coolant is brought into direct contact with the underside of the chip. Infrared (IR) thermal imaging was used to quantify the reduction in junction temperature, and simultaneous RF measurements of output power and drain current were used to quantify the RF benefits. The results show a 3× reduction in thermal resistance and 4.2 dB increase in gain for a given input power. In addition, the microfluidically cooled HPA produced over 8 dB increased output power. Finally, embedded cooling also improved the power added efficiency (PAE) of the amplifier by roughly 3× to 4× compared to its remotely cooled counterpart.