This paper presents a band-switchable RF power amplifier (PA) fully-integrated in 130nm CMOS process. A two-stage power amplifier with switchable input and output matching networks is designed in order to tune the center frequency in use. The proposed CMOS PA can operate at 900MHz and 1900MHz as lower and higher operating bands, respectively. Thus, Long Term Evolution-advanced (LTE-a) and quad-band GSM standards for cellular applications can he covered. As a result, the designed band-switchable power amplifier obtains small-signal gain (S21) of 31.2dB/32.0dB, saturated output power (Psat) of 22.72dBm/ 23.36dBm, and power added efficiency (PAE) of 23.0 %/ 26.5% at the lower and higher frequency bands, respectively, showing promising advancement compared to the state-of-the-art.