Digitally Modulated CMOS Polar Transmitters for Highly-Efficient mm-Wave Wireless Communication

A mm-Wave Switched-Capacitor RFDAC

“…Hence, significant work has been done in mmW transceivers. Bringing direct-digital transmitters, including RFDACs [21], [22], to the mmW band has proven challenging due to the limited switching speed of CMOS transistors. Although challenging to implement, there are obvious advantages to the direct-digital RFDAC approach, such as enabling fully connected digital beamforming [9].…”

“…The synthesized impedance variation technique shows a means to compensate for the distributed effects in the combination network and increases η SE up to 22%. A DPA with non-constant envelope-modulation class-E at 60 GHz in [21] obtained 17.7% efficiency, while a polar RFDAC with a transformer-coupled two-stage PA [22] achieved 15.3% efficiency.…”

Quantized Polar Transmitters for Power Efficient Massive MIMO Systems

“…In this work, a digital polar transmitter architecture [7], [8] is adopted at the BS, instead of the conventional and popular Cartesian architecture. Fig.…”

“…Alternatively, the digitally modulated polar transmitter architecture is an attractive option to the Cartesian architecture, to enable the challenging combination of wideband, powerefficient and linear operation at low cost [6]- [8]. A highlevel illustration of the digital polar architecture is shown in Fig.…”

A 2 × 6b 8 GS/s 17–24-GHz I/Q RF-DAC-Based Transmitter in 22-nm FDSOI CMOS

“…For complex modulation formats, RF-DACs can be used in a polar or a Cartesian configuration. The polar IQ-modulator applies amplitude and phase in two separate steps, requiring these signals to be time-aligned with sub-sample precision [5], which is very challenging for wideband signals. The Cartesian IQ-modulator uses two RF-DACs with a 90°phase offset to generate I-and Q-components; but combining these without losses and impairments is complex.…”