8
S. Kar
Fig. 6 Schematic of the 1.0-THz GaN DDR IMPATT [10]
2.4 The Integrated Power Module
In the integrated power module, the IMPATT diode to be used is the seed diode of the
type mentioned in Fig. 6 and it need not be a packaged diode; the latter being used
in waveguide mounted oscillator of different types discussed in Fig. 2. Further, in
integrated power module, no actual resonant-cap structure mounting in waveguide is
needed. In fact, two more metallization steps one at the beginning and the other at the
end of the diode fabrication process complete the power module structure as shown
in Fig. 7. The ground plane (of conventional microstrip antenna) at the bottom of
the integrated module (vide Fig. 7) has to be formed first of suitable material (highly
conducting). Then the 1 THz seed IMPATT diode shown in Fig. 6 will be fabricated
in different steps, and finally, a thin metallic slotted disc (of proper dimension)
has to be realized with another metallization in the same planer fabrication process
schedule. The whole module will act as an improvised slotted-disc-type microstrip
patch antenna being fed by the seed IMPATT device embedded in the improvised
resonant-cap cavity formed with top and bottom E-walls bounded by open H-wall