Low-power offset-calibrated CMOS I/Q transmit interface for portable communications

This paper describes a low-power mixed signal integrated system for an 8-bit I/Q D/A interface with an RF modulator for portable communications. Measurement results show INL and DNL errors below the 8 bit level, a THD better than - 55 dB and amplitude and phase errors between channels respectively smaller than 0.1 dB and ± 0.625 degrees. The complete circuit operates with a power supply of nominally 3 V, occupies less than 4 mm²of silicon area in a 0.5 µm standard CMOS process and dissipates less than 8 mW.