A PLL-based phased array method to minimize phase quantization errors and reduce phasing-lobes

Phase quantization error is defined as the difference in the ideal and discretized inter element phase delays and is dependent upon the delay resolution of the ultrasound imaging system. Large quantization error values can create phasing lobes which cause beam anomalies and may degrade image quality. Described is a method which uses Phase Locked Loop (PLL) components embedded within standard Field Programmable Gate Array (FPGA) technology to generate multiple phase shifted clocks. These clocks are used to create excitation waveforms with minimized phase quantization error (≤1 ns). The design has been successfully implemented on an 8 channel transmitter board and then replicated to be included within a bespoke 96 channel Ultrasound Array Research Platform (UARP).