Common-Gate Load-Pull With Q-Band Application

A new technique is proposed for the design of linear power amplifiers at millimeter-wave frequencies where load-pull of large transistor output cells is difficult. The technique transforms the load-pull data on a small, standard foundry transistor layout to a pair of common-gate contours for the intrinsic device; one source-gate and one drain-gate. These are recombined as an intrinsic drain-source contour for a larger and arbitrary transistor layout. A Q-band driver amplifier for the ETSI 42-GHz point-to-point radio band has been designed using the proposed technique. The fabricated MMIC consumes 1 W and has a gain of 21 dB, with OIP3 of 35 dBm, OIP5 of 28 dBm and P1 dB of 23 dBm. The PAE is approximately 19%. The OIP3 to P1 dB and OIP3 to dc power ratios are believed to be the best reported to date.