  We report results from a detailed study of the neutron star X-ray binary, 4U
1608-52 using observations with {\it AstroSat} (LAXPC/SXT) and {\it NICER}
during its 2016 and 2020 outbursts. The 0.7--20.0 keV spectra could be well
described with the disk blackbody and thermal Comptonization model. The
best-fitting inner disk temperature is $\sim$ 1 keV and radius { $\sim$
22.17$^{+2.57}_{-2.38}$--27.19$^{+2.03}_{-1.85}$} km and no significant
evolution was observed in the disk radius after performing flux and
time-resolved spectroscopy. We used a multi-Lorentzian approach to fit the
power density spectra and obtained broad-band noise variability. We estimated
the energy-dependent fractional root mean square and time-lag of the broad-band
noise, and these variations are quantitatively modelled as being due to the
coherent variation of the disk emission and the coronal heating rate. Thus, the
rapid temporal modeling is consistent with the longer term spectral evolution
where the inner disk radius does not vary, and instead the variations can be
attributed to accretion rate variations which changes the inner disk
temperature and the coronal heating rate.
