Transmitter architecture using digital generation of RF signals

This paper describes architecture for a CDMA RF transmitter implemented in digital CMOS. The functions of up-conversion and filtering are carried out in the digital domain. A band-pass delta-sigma modulator is used to produce a one-bit output containing the desired analog signal, which is then fed to switching-mode power amplifier. Issues for the digital logic implementation to facilitate proper modulator operation at the required high clock rates (>3.3 GHz) are discussed in detail.