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In this letter, a multi-level and multi-band Class-D CMOS power amplifier (PA) in a standard 0.18 ??m CMOS process is presented. Using multiple PMOS devices with control switches, the proposed PA improves efficiency with the multi-level operation. In order to enable the multi-band operation, the proposed PA employs a tunable series resonator. The measured maximum drain efficiencies were 72% and 70% for the low power mode and high power mode, respectively. The 3 dB bandwidth of the proposed system was from 450 MHz to 730 MHz, which covers the cognitive radio white spectrum standard. The measured EVM using a commercial 16QAM OFDM signal was -34 dB with a LINC system.