  We present the results obtained from broadband X-ray timing and spectral
analysis of black hole candidate MAXI J1803-298 using an AstroSat observation
on May 11-12, 2021. Four periodic absorption dips with a periodicity of $7.02
\pm 0.18$ hour are detected in the light curve. AstroSat observe the source
when it was undergoing a transition from hard-intermediate state to
soft-intermediate state. Our timing analysis reveals the presence of a sharp
type-C quasi periodic oscillation (QPO) in the power density spectra (PDS) with
an evolving QPO frequency ranging from $5.31 \pm 0.02$ Hz to $7.61\pm 0.09$ Hz.
We investigate the energy dependence of the QPO and do not find this feature in
the PDS above 30 keV. The combined $0.7-80$ keV SXT and LAXPC spectra are
fitted with a model consisting of thermal multi-colour blackbody emission and
Comptonized emission components. We perform time-resolved spectroscopy by
extracting spectra during the dip and non-dip phases of the observation. A
neutral absorber is detected during the dip and non-dip phases though a
signature of an ionized absorber is also present in the dip phases. The
spectral and temporal parameters are found to evolve during our observation. We
estimate the mass function of the system as $f(M) = 2.1-7.2~M_{\odot}$ and the
mass of the black hole candidate in the range of $M_{\rm BH} \sim
3.5-12.5~M_{\odot}$.
