Zhang Xitie, Arkan Evren F, Tekes Coskun, Kilinc M Sait, Wang Tzu-Han, Degertekin F Levent, Li Shaolan
IEEE Trans Biomed Circuits Syst. 2025 Feb;19(1):174-184. doi: 10.1109/TBCAS.2024.3409162. Epub 2025 Feb 11.
Intravascular ultrasound (IVUS) imaging catheters are significant tools for cardiovascular interventions, and their use can be expanded by realizing IVUS imaging guidewires and microcatheters. The miniaturization of these devices creates challenges in SNR due to the need for higher frequencies to provide adequate resolution. An integrated IVUS system with transmit beamforming can mitigate these limitations. This work presents the first practical highly integrated system-on-a-chip (SoC) with plane wave transmit beamforming at 40 MHz for IVUS on guidewire or microcatheters. The front-end circuitry has a 20-channel ultrasound transmitter (Tx) and receiver (Rx) array interfaced with a capacitive micromachined ultrasound transducer (CMUT) array. During each firing, all 20 Tx are excited with the same analog delay with respect to each other, which can be continuously adjusted between 0 and 10 ns in two directions, generating a steerable plane wave in a range of +/-50 for a phased array at 40 MHz. The unit delays are generated via a voltage-controlled delay line (VCDL), which only needs two external controls, one tuning the unit delay and the other determining the steering direction. The SoC is fabricated using a 180-nm high-voltage (HV) CMOS process and features a slender active area of 0.3 mm 3.7 mm. The proposed SoC consumes 31.3 mW during the receiving mode. The beamformer's functionality and the SoC's overall performance were validated through acoustic characterization and imaging experiments.
血管内超声（IVUS）成像导管是心血管介入治疗的重要工具，通过实现IVUS成像导丝和微导管，其应用范围可以得到扩展。由于需要更高的频率来提供足够的分辨率，这些设备的小型化给信噪比带来了挑战。具有发射波束形成功能的集成IVUS系统可以减轻这些限制。本文介绍了首个实用的高度集成片上系统（SoC），该系统在40 MHz频率下为导丝或微导管上的IVUS提供平面波发射波束形成功能。前端电路有一个20通道的超声发射器（Tx）和接收器（Rx）阵列，与电容式微机械超声换能器（CMUT）阵列相连。在每次发射时，所有20个Tx相互之间以相同的模拟延迟被激发，该延迟可以在两个方向上在0到10 ns之间连续调节，对于40 MHz的相控阵，在+/-50°范围内产生一个可控平面波。单位延迟通过压控延迟线（VCDL）产生，该延迟线仅需要两个外部控制，一个用于调节单位延迟，另一个用于确定转向方向。该SoC采用180 nm高压（HV）CMOS工艺制造，有源区细长，尺寸为0.3 mm×3.7 mm。所提出的SoC在接收模式下功耗为31.3 mW。通过声学特性表征和成像实验验证了波束形成器的功能和SoC的整体性能。
