The optical aperture of the antenna is an important technical indicator of the liquid crystal optical phased array. Based on the multi-subarray parallel driving and two-level device cascade method (PAPA), in this paper, an improved i-PAPA method was proposed. Large area phased beam control is realized on a single phased array antenna by subdivision of the COM electrodes, and it has the advantages of single device operation and low insertion loss. Through numerical simulation, the results show that the antenna near field phase has continuous distribution; when the point angle varies from 0 degrees to +6 degrees, the far-field diffraction efficiency drops smoothly and monotonously as the point angle increases, the diffraction efficiency is greater than 48%; When the point angle varies from 0 degrees to +3 degrees, the diffraction the efficiency is greater than 80%.