In this paper, we present a ribbon cell CMOS power amplifier in which the structure of the power cell is like a ribbon. As the frequency increases, the output impedance decreases due to parasitic capacitors, so an interstage inductor is used. The interstage inductor used in previous research has the problem of increasing the size of the chip. Ribbon cells use larger interstage inductors through mutual inductance. Therefore, a metal smaller than the desired inductor metal size can be used. This allows the chip size to be designed to be small. It also improves AM-PM distortion and IMD3. It operates at 28 GHz with a 2.4 V supply voltage and achieves IMD3 of -40dBc at 10 dBm output power and -30dBc at 12.3 dBm output power and PAE of 19% and 25% respectively. It has a saturated output power of 18.4dBm and achieves a gain of 11.6dB at a P1dB of 16.4dBm.