Digital phased array beamforming using single-bit delta-sigma conversion with non-uniform oversampling

Digital beamforming based on oversampled delta-sigma (Delta Sigma) analog-t o-digital (A/D) conversion can reduce the overall cost, size: and power con sumption of phased array front-end processing. The signal resampling involv ed in dynamic Delta Sigma beamforming, however, disrupts synchronization be tween the modulators and demodulator, causing significant degradation in th e signal-to-noise rat-io. As a solution to this, we have explored a new dig ital beamforming approach based on non-uniform oversampling Delta Sigma A/D conversion. Using this approach, the echo signals received by the transduc er array are sampled at time instants determined by the beamforming timing and then digitized by single-bit Delta Sigma A/D conversion prior to the co herent; beam summation. The timing information involves a non-uniform sampl ing scheme employing different clocks at each array channel. The Delta Sigm a coded beamsums obtained by adding the delayed 1-bit coded RF echo signals are then processed through a decimation filter to produce final beamformin g outputs. The performance and validity of the proposed beamforming approac h are assessed by means of emulations using experimental raw RF data.