In this study, a digital dechirp approach for Synthetic Aperture Radar (SAR) is discussed. It can be applied to lightweight MiniSar systems with longer pulse width than swath. With this method, and after data acquisition with lower sampling rate than the bandwidth of the transmitted LFM signal and digital dechirp, pulse compression can be obtained by spectral analysis in the range direction without aliasing. The approach is described in detail and the sampling frequency selection criteria are derived. Theoretical formulations and numerical simulations verify the validity of the proposed approach.