In our paper with M. E. H. Ismail [7], we are interested in studying the zeros of a family of entire functions introduced by Ramanujan, using contour integrals and connection formulas for solutions of linear q-difference equations. Many years ago, M. E. H. Ismail provided a simple proof of Ramanujan’s \(_1\psi _1\) summation formula [6]. In this note, we aim to present an analytic proof of this formula using similar approaches to those in [7]. Furthermore, building on these methods, we derive a decomposition formula for the sum-function of a q-analog of the Euler series, which has the potential to be generalized to a broader class of q-difference equations.