A Two-Beam Eight-Element Direct Digital Beamforming RF Modulator in 40-nm CMOS.

A digital eight-element beamforming RF modulator allows accurate steering of multiple independent beams. The key to the efficiency is the pairing of area-efficient bandpass $\Delta \Sigma $ modulation with N-path filtering to suppress quantization noise. Beamforming digital signal processing (DSP) is enabled by careful frequency management, which facilitates efficient digital phase shifting, upsampling, and upconversion. A 40-nm CMOS prototype generates two 1.2-GHz beams, with 40-MHz RF bandwidth. The prototype consumes 128 mW and occupies an active area of only 0.19 mm2, which is only 16 mW and 0.02 mm2 per element. This represents an order-of-magnitude improvement in area and power consumption per element compared to the state-of-the-art digital to RF modulators. [ABSTRACT FROM AUTHOR]