H. Eisele et Gi. Haddad, ENHANCED PERFORMANCE IN GAAS TUNNETT DIODE OSCILLATORS ABOVE 100-GHZ THROUGH DIAMOND HEAT SINKING AND POWER COMBINING, IEEE transactions on microwave theory and techniques, 42(12), 1994, pp. 2498-2503
Single-drift GaAs TUNNETT diodes on integral heat sinks with RF power
levels up to 40 mW at 102.33 GHz exhibit no sign of saturation in RF o
utput power or efficiency and are thought to be thermally limited. The
refore, diodes from the same MBE grown material were fabricated using
a different selective etching technology and mounted on diamond heat s
inks for improved heat dissipation. RF output power levels of up to 95
mW with corresponding dc-to-RF conversion efficiencies of 5.85% were
measured at 104.16 GHz. To further increase the available RF output po
wer, two TUNNETT diodes at a time were power combined using two radial
line full-height waveguide cavities. The combined RF output power was
46 mW at 102.3 GHz from two diodes on integral heat sinks and 142 mW
at 103.87 GHz from two diodes on diamond heat sinks with corresponding
combining efficiencies of 80% and more. This is the first successful
demonstration of power combining with TUNNETT diodes and the power lev
els and efficiencies from either single or combined diodes are the hig
hest reported to date from any devices made of III-V materials (eg., G
aAs and InP). Single diodes in second-harmonic mode yielded RF power l
evels of 0.57 mW at 219.7 GHz and 0.19 mW at 235.7 GHz.