GaAs LSA V-band oscillators

GaAs devices verify practical LSA mode operation at V-band frequencies (50-75 GHz). The limitations on power and efficiency are characterized including the dependence of efficiency on electron concentration. The maximum CW power level is 62 mW with an efficiency of 2.2 percent at 64 GHz. The peak power and efficiency is 137 mW and 3.71 percent at 64 GHz for 5 percent duty, pulsed operation. A maximum in the CW efficiency occurs at an n/f ratio of 1.1 × 10⁵s . cm^-3corresponding to a doping of 6.6 × 10¹⁵cm^-3for a frequency of 60 GHz. Device design curves are presented for CW operation subject to Copeland's LSA mode criteria and to a maximum allowed sample temperature rise. Details of a vane circuit are presented which provide V-band resonances and a proper RF environment for LSA-related operation.