Fourier-Domain DAC-based Transmitter: New Concepts Towards the Realisation of Multigigabit Wireless Transmitters

A Fourier-Domain digital-to-analogue converter (FDDAC) based transmitter is presented for the first time. The proposed topology generates a coherent bandwidth in the GHz range exploiting the Fourier Transform concept. Thus, the DAC sampling rate is reduced by up to two orders of magnitude compared to conventional transmitters. Moreover, it provides an intrinsic spectral shaping of the digital input signal. Thus, no complex signal processing in terms of oversampling and filtering is required in order to achieve a clean transmit signal with low out-of-band emissions. The feasibility of the proposed concept is validated by designing a fully integrated prototype transmitter including signal processing in 65 nm CMOS technology. It generates a single-carrier signal with a bandwidth of up to 2 GHz and a modulation order of up to 16QAM in the sub 6-GHz frequency range. The occupied chip area is 1.34 mm
²
. The achieved EVM is -9.4 dB for a QPSK modulated signal.