Orthogonal summing and power combining network in a 65-nm all-digital RF I/Q modulator

This paper elaborates on the recently introduced concept of an all-digital RF I/Q modulator. Orthogonal summation and design procedure of the power combining network are explained in more detail. A 65 nm CMOS prototype is implemented based on this concept. The prototype achieves 12.6 dBm peak output power and 20% peak drain efficiency at 2 GHz. While providing 6 dBm output power, the error vector magnitude (EVM) is 3.7%.