This paper presents three CMOS power amplifiers (PA) which realize wide-tunable output impedance matching. For realization of multi-standard and single-chip transceiver, the prototypes were fabricated by 0.18µm CMOS process. The proposed PAs can achieve a tunable impedance matching within a wide frequency range by utilizing a resistive feedback and parallel resonator with an inductor and capacitor array. Therefore, the proposed PA has a realization possibility of isolator-less PA which contributes to decrease die area including external component. In other words, the PAs have tunable impedance matching function at their output ends. With a 3.3-V supply, three power amplifiers can cover frequency ranges of 0.9-3.0GHz, 2.1-5.8GHz, and 5.7-9.7GHz, respectively. The PAs realize P_1dB of 21dBm, P_sat of 22dBm, and PAE_peak of larger than 23%. The proposed PAs present a potential to realize multi-band transceivers without isolators.