A 0.19mm 2 128mW 0.8-1.2GHz 2-Beam 8-Element Digital Direct to RF Beamforming Transmitter in 40nm CMOS

An order of magnitude improvement in area and power consumption per element is achieved by digital phase shifting combined with bandpass Δ∑ modulation and N-path filtering. The 8-element beamforming transmitter allows accurate steering of multiple independent beams. Key to the efficiency are the pairing of area-efficient bandpass ΔΣ modulation with N-path filtering to suppress quantization noise and careful frequency management to allow efficient digital phase shifting and up-conversion. The 40nm CMOS prototype generates two independent 1.2GHz beams, it consumes 128mW and occupies an active area of only 0.19mm 2 , consuming only 16mW and 0.02mm 2 per element.