Abstract: To improve the imaging quality in the minimum variance method of low complexity， an improved low-complexity amplitude and phase estimation beamforming algorithm was proposed. The adaptive weighted value was calculated by extracting the effective rows of the covariance matrix， where the selection of the effective number of rows was determined by a more accurate Gaussian phase coherence coefficient， which was then used to modify the weighting vector in order to reduce the complexity and ensure the quality of the imaging at the same time. Through experimental verification， the improved algorithm was compared with the original algorithm and another beamspace method to reduce the complexity， which fully proves the superiority of the improved algorithm in reducing the complexity and improving the imaging quality.

Key words: low complexity, phase coherence factor, amplitude and phase estimation, beamforming, ultrasound image