A Ka-Band Balanced Four-Beam Phased-Array Receiver With Symmetrical Beam-Distribution Network in 65-nm CMOS

This paper demonstrates a Ka-band CMOS phased-array receiver capable of generating four balanced beams from two inputs. A passive four-beam symmetrical differential network is proposed to distribute two input signals to eight channels and facilitate beam generation at the outputs in the receiver. The detailed design and optimization of the passive four-beam differential network are presented. Using a 6-bit passive vector-modulated phase shifter and a 5-bit switched-type attenuator in each channel, we implement a phase control of 360° with<; 4° RMS phase error and a gain control of 17 dB with <; 0.35 dB RMS gain error from 27 to 31 GHz. The receiver consumes a current of only 40 mA under 1 V supply voltage. Eight channels of the four-beam phased-array receiver were measured and a gain mismatch of less than 0.3 dB has been achieved. Beam to beam couplings are investigated by measurements and beam-to-beam isolation are better than 32 dB from 27 to 31 GHz. The chip size is 2.6×4 mm
²
including all digital control circuitry and pads.