  A correlation is established between the theories of superconductivity based
on the concept of charge density waves (CDW) and the translation invariant (TI)
bipolaron theory. It is shown that CDW are originated from TI-bipolaron states
in the pseudogap phase due to Kohn anomaly and form a pair density wave (PDW)
for wave vectors corresponding to nesting. Emerging in the pseudogap phase, CDW
coexist with superconductivity at temperatures below that of superconducting
transition while their wave amplitudes decrease as a Bose condensate is formed
from TI-bipolarons, vanishing at zero temperature.
