This paper presents a fully integrated wideband CMOS power amplifier (PA) with Digitally Assisted Wideband Pre-Distorter (DAWPD) and tunable transformer. The DAWPD is implemented at the driver amplifier to establish a pre-distorter linearizing mechanism across the wide frequency bandwidth. The DAWPD mechanism has an integrated Digital Linearizer (DL), which is controlled via digital bits. The DAWPD-PA also integrates with a tunable transformer employed at its output matching network to achieve optimum efficiency and output power performance across a wideband frequency. The DAWPD-PA has been fabricated in CMOS 130 nm and has an operating bandwidth of 1 GHz from 1.7 to 2.7 GHz. The gain achieved is 26.9 to 29.7 dB across the frequency. The linear output power and PAE achieved across the operating frequency are 24.0 to 25.1 dBm and 34.5 to 38.8%.