  Superdeformed states in light $N=Z$ nuclei are studied by means of the
self-consistent cranking calculation (i.e., the P + QQ model based on the
cranked Hartree-Fock-Bogoliubov method). Analyses are given for two typical
cases of superdeformed bands in the $A \simeq 40$ mass region, that is, bands
where backbending is absent ($^{40}$Ca) and present ($^{36}$Ar). Investigations
are carried out, particularly for the following points: cross-shell excitations
in the sd and pf shells; the role of the g$_{9/2}$ and d$_{5/2}$ orbitals; the
effect of the nuclear pairing; and the interplay between triaxiality and band
termination.
