A High-Power RF GaN Amplifier Using Bondwire Transformer for Interstage Match

A novel interstage match design using a parallel bondwire transformer is presented. Impedance transformation from the input of a GaN HEMT final stage to output of a GaN HEMT driver stage is achieved in part with a 1:4 wire ratio of the primary and secondary bondwires, as well as capacitive matching components in an interdigitated capacitor array. Analysis of the impedance transformation and extraction of the transformer parameters is shown using simulated data from a 3-D model of the interstage match. A fabricated prototype of a 2-stage GaN power amplifier using the transformer interstage match is shown. At 2.6GHz and maximum efficiency load, the amplifier has 30dB of linear gain, with 200 W output power and 69% drain efficiency for the final stage at 3dB compression.