  We define a new parameter $A'_{k,n}$ involving Ramanujan's theta-functions
for any positive real numbers $k$ and $n$ which is analogous to the parameter
$A_{k,n}$ defined by Nipen Saikia \cite{NS1}. We establish some modular
relation involving $A'_{k,n}$ and $A_{k,n}$ to find some explicit values of
$A'_{k,n}$. We use these parameters to establish few general theorems for
explicit evaluations of ratios of theta functions involving $\varphi(q)$.
