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

Digital beamforming based on oversampled delta-sigma (/spl Delta//spl Sigma/) analog-to-digital (A/D) conversion can reduce the overall cost, size, and power consumption of phased array front-end processing. The signal resampling involved in dynamic /spl Delta//spl Sigma/ beamforming, however, disrupts synchronization between the modulators and demodulator, causing significant degradation in the signal-to-noise ratio. As a solution to this, we have explored a new digital beamforming approach based on non-uniform oversampling /spl Delta//spl Sigma/ A/D conversion. Using this approach, the echo signals received by the transducer array are sampled at time instants determined by the beamforming timing and then digitized by single-bit /spl Delta//spl Sigma/ A/D conversion prior to the coherent beam summation. The timing information involves a nonuniform sampling scheme employing different clocks at each array channel. The /spl Delta//spl Sigma/ coded beamsums obtained by adding the delayed 1-bit coded RF echo signals are then processed through a decimation filter to produce final beamforming outputs. The performance and validity of the proposed beamforming approach are assessed by means of emulations using experimental raw RF data.