This paper presents a new delta-sigma-based transmitter architecture with quantization noise reduction and coding efficiency enhancement for multi-mode wireless sensor network (WSN) applications. The proposed architecture utilizes a finite impulse response (FIR) filter embedded digital power amplifier (DPA) controlled by the output of a 1-bit second order low pass delta-sigma modulator (LPDSM) for both in-phase (I) path and quadrature (Q) path. Thanks to the interleaving operation of the FIR filter, the out-of-band noise is reduced hence coding efficiency is improved according to the behavior model simulation results. Since the switching of power amplifier (PA) is smoothed by FIR, distortion from the PA is also suppressed.