A Study of High-Frequency Bandpass Delta-Sigma Transmitter Architectures

This paper proposes a novel architecture to realise a highly-efficient and linear bandpass (BP) delta-sigma (DeltaSigma) transmitter. The novel transmitter topology takes advantage of the fact that nowadays digital signals are in-phase (/) and quadrature (Q) modulated. Instead of using the combined signal, the proposed architecture processes the RF I and Q signals in two separate branches and combines them only prior transmission over the antenna. Doing so has several benefits in regard to practical implementation since the signal bandwidths in the proposed system are narrower than in the conventional architecture. Simulations of such a transmitter using GaAs FETs highlights the potential of the novel RF I/Q BPDeltaSigma architecture as it features high-linearity as well as better signal-to-noise ratio than the conventional topology.