A 0.8–1.9GHz-band CMOS direct digital RF quadrature modulator

A 0.8–1.9 GHz direct digital radio frequency (RF) quadrature modulator is designed and fabricated in 90 nm CMOS process. The bit number and the CLK frequency of I/Q digital input signals are designed to satisfy the required EVM, ACPR/NACPR and system bandwidth for 0.9/1.9GHz W-CDMA terminals. The fabricated quadrature modulator performs EVM of less than −22.7dB, ACP/NACP of less than −36.1dBc and spurious free range of 197MHz (wider than the W-CDMA system bandwidth of 60MHz) with 8-bit, 100Msps I/Q digital input signals and the d.c. power consumption of 10mW.