为了提高内镜超声成像质量, 本文提出一种基于高精度数字波束合成的内镜超声相控阵成像方案。在传统数字波束合成方法基础上, 利用高采样率ADC 设计了新的数字波束合成器, 与传统数字波束合成方法相比, 新方法的延时精度由8 ns 提高到1.4 ns。利用数字波束合成技术, 实现各通道回波信号的高精度逐点动态聚焦合成; 利用数字正交解调技术, 实现数字波束合成信号包络幅值的提取。对水槽中铁丝进行相控扫描成像实验, 实验结果表明使用数字波束合成能够显著抑制旁瓣, 横向分辨力提高25%, 信噪比提高3.7 dB。

A method for endoscopic ultrasonic phased array imaging was proposed based on high-precision digital beamforming. Based on conventional digital beamforming, a new digital beamformer with A/D converter of high sampling rate was designed. Compared with the conventional digital beamformer, the delay precision of the new digital beamformer is upgraded to 1.4 ns from 8 ns. In this paper, we used the new digital beamformer to synthesize the ultrasonic signals received by the array elements. Then we utilized the digital quadrature demodulation circuit to realize envelope extraction of the synthetic ultrasonic signal. Finally, using iron wires in water tank as experimental sample, the experiment results show that using the digital beamforming technology, the peak sidelobe is effectively suppressed, and the lateral resolution and SNR are improved by 25% and 3.7 dB respectively.