A 30-MHz-to-3-GHz CMOS array receiver with frequency and spatial interference filtering for adaptive antenna systems

A 30-MHz-to-3-GHz wideband CMOS phased array receiver with interference suppression capability in frequency and spatial domains is presented. A frequency filtering function is provided by a 16-phase, two-stage harmonic rejection mixer which also works as a 5-bit phase shifter in multi-chip phased array systems. Equipped with 6-bit amplitude control in addition to the phase, the array receiver enables analog null steering that can reduce a spatial interferer coming from a specific direction. The developed IC achieves more than 55-dB suppression of harmonic interference in the wide range from 30 MHz to 3 GHz. The multiple ICs configure a four-element adaptive array system for the measurement of space propagation. It is confirmed that the null steering function reduces spatial interference by 20 dB and improves an EVM from -12.7 dB to -26.3 dB even when a strong interferer exists.