This brief presents the design of a band-tunable 60-GHz CMOS power amplifier using 65-nm standard CMOS technology. To achieve high gain and PAE over the whole 7-GHz frequency band, this amplifier utilizes a differential band switching circuit to tune the center frequency to the channel in use, whereas high-Q transformer matching and deep-neutralized differential pairs are employed to achieve high gain and PAE in a narrow bandwidth. The amplifier achieves saturated output power of 12.3 dBm and peak PAE of 20.4% with a 1-V supply and a 63-mA current. The peak gain is 17.1 dB at 59 GHz and 16.2 dB at 53.5 GHz for the two different frequency bands, respectively.