An 8GHz multi-beam spatio-spectral beamforming receiver using an all-passive discrete time analog baseband in 65nm CMOS

A novel multi-frequency beamforming front-end is proposed. The proposed front-end allows for simultaneous and independent steering of multiple frequency beams. As proof of concept, an 8GHz 2-channel, 4-frequency phased array beam-former is designed and implemented in 65nm CMOS. The IF signal on each channel is frequency split using an all passive 4-point analog FFT. The orthogonal frequency outputs are then beam steered using an all passive I-Q vector combiner. The RF circuit draws 22.8mA from a 1.2V supply while the analog baseband consumes 9pJ/conv. (135μW at 120MSps).