A 30-MHz–3-GHz CMOS Array Receiver With Frequency and Spatial Interference Filtering for Adaptive Multi-Antenna Systems

A 30-MHz-3-GHz wideband complementary metal- oxide-semiconductor phased array receiver with interference suppression capability in the frequency and spatial domains is presented. A frequency filtering function is provided by a two-stage harmonic rejection mixer with 16-phase local oscillator (LO) signals that are generated by frequency dividers and phase interpolators. The developed IC suppresses third- to seventh-order harmonic interference by more than 55 dB in a wide range from 30 MHz to 3 GHz. The 16-phase LO signal generator combined with a 2-b baseband phase shifter (PS) also works as a 6-b PS. Equipped with a 6-b amplitude control in addition to the 6-b phase control, the array receiver enables analog null steering that can reduce a spatial interference coming from a specific direction. The multi-chip synchronization needed for the null steering function is realized with pre-set circuits in the frequency dividers. Space propagation measurements made on a four-element array antenna system using the developed ICs indicated that the null steering function reduces spatial interference by 20 dB and reduces the error vector magnitude of a 2-GHz radio frequency, 20-MHz bandwidth, and 64-quadrature amplitude modulation signal from -12.7 to -26.3 dB even when a strong interferer exists.