Dynamic power supply design for high-efficiency wireless transmitters using GaN FETs D. Cucak The topic of this project is application of GaN FETs and filter design methodology in a dynamic power supply for highly efficient wireless transmitters. The main objectives of the filter design are generation of the envelope reference with minimum possible distortion and high efficiency of the amplifier obtained by the optimum trade-off between conduction and switching losses. This optimum point was determined using power losses model for synchronous buck with sinusoidal output voltage. On the other hand, application of GaN FETs showed significant efficiency enhancement comparing to the prototypes with Si MOSFETs with good values for FOM. Project sponsored by Motivation and Objective Envelope Tracking and Envelope Elimination and Restoration techniques Synchronous Buck as Envelope Amplifier GaN FETs Wireless and broadband services – growing on a daily basis Radio base stations – low efficiency! The main reason – poor efficiency of linear amplifier ET and EER – efficiency increasement techniques Envelope Amplifier needs to have Fast dynamic response (bandwidth and slew rate) High efficiency Proposed topology: Synchronous Buck with GaN FETs GaN devices – significantly better FOM! Device Type Vds_max [V] Ron[mΩ] QG[mΩ] (Vgs=5V) FOM EPC1015 GaN 40 4 11.6 46.4 EPC1014 16 3 48 BSC016N04LSG Si 2.3 60 138 Efficiency measurements Static characteristics: Vin=24V, Rload=4Ω, variable duty cycle Dynamic measurements: 64QAM and WCDMA, switching frequency: 5MHz 64QAM, BW=1MHz RLOAD = 4Ω EPC1014 EPC1015 PD57070 BSC016N04LSG Pout, avg[W] 41.1 43.3 42.8 42.7 Eff [%] 87.6 85.9 78 84.2 WCDMA, BW=500kHz RLOAD = 3Ω EPC1014 EPC1015 PD57070 BSC016N04LSG Pout, avg[W] 31.2 32.3 31.8 32.6 Eff [%] 87.2 79.8 79.3 82.6 Filter design methodology Vout 𝑖 𝐿 𝑖 𝐿𝑜𝑎𝑑 (j2π 𝐹 𝑚𝑜𝑑 ) = A Design parameter The optimum trade-off between the conduction and switching losses. How to minimize the losses by filter design? Modeling of GaN devices Developed high frequency black box model for commercially available EPC GaN FETs Switch-based large signal model: losses & performance prediction of our topology Modeling of GaN devices Two main goals A physical model that provides a dependence of the switching behaviour and power losses on the technological parameters of the transistor CONCLUSIONS The obtained efficiency measurements showed significant efficiency enhancement by application of GaN FETs comparing to standard Si MOSFETs. For 64QAM and WCDMA signals, EPC1014 prototype showed around 5% higher efficiency comparing to fast switching Si BSC016N04LSG, at 5MHz of switching frequency. Filter design methodology for optimum trade-off between the bandwidth and efficiency was proposed and experimentally verified for sinusoidal output voltage.