Digital centric IF-DAC based heterodyne transmitter architecture

Abstract

This paper introduces the intermediate frequency digital-to-analogue converter which realizes the implementation of a digital centric heterodyne transmitter. A single digitally switching block is capable of mixing the local oscillator and intermediate frequency and performing the digital-to-analogue conversion. Furthermore, the analogue mixer and filter blocks which perform poor in nano-scale CMOS technologies are omitted. Therefore, the proposed heterodyne transmitter can scale with CMOS technology generations. As a proof-of-concept the proposed intermediate frequency digital-to-analogue converter is utilised to implement a heterodyne transmitter in a TSMC 65 nm CMOS technology. This transmitter employs a 16 point quadrature amplitude modulated signal with a bandwidth of 40 MHz at a carrier frequency of 2.4 GHz. Moreover, the output signal provides an 800 MHz spurious free band around the centre frequency.