Chao Chen

Publications

  1. A 2000-volumes/s 3-D Ultrasound Probe With Monolithically-Integrated 23 $\times$ 23-mm2 4096-Element CMUT Array
    Rozsa, Nuriel N. M.; Chen, Zhao; Kim, Taehoon; Guo, Peng; Hopf, Yannick M.; Voorneveld, Jason; dos Santos, Djalma Simoes; Noothout, Emile; Chang, Zu-Yao; Chen, Chao; Henneken, Vincent A.; de Jong, Nico; Vos, Hendrik J.; Bosch, Johan G.; Verweij, Martin D.; Pertijs, Michiel A. P.;
    IEEE Journal of Solid-State Circuits,
    pp. 1--14, 2025. early access. DOI: 10.1109/JSSC.2025.3534087
    Abstract: ... This article presents a 4096-element ultrasound probe for high volume-rate (HVR) cardiovascular imaging. The probe consists of two application-specific integrated circuits (ASICs), each of which interfaces with a 2048-element monolithically-integrated capacitive micro-machined ultrasound transducer (CMUT) array. The probe can image a 60∘ × 60∘ × 10-cm volume at 2000 volumes/s, the highest volume-rate with in-probe channel-count reduction reported to date. It uses 2 × 2 delay-and-sum micro-beamforming (μBF) and 2× time-division multiplexing (TDM) to achieve an 8× receive (RX) channel-count reduction. Equalization, trained using a pseudorandom bit-sequence generated on the chip, reduces TDM-induced crosstalk by 10 dB, enabling power-efficient scaling of the cable drivers. The ASICs also implement a novel transmit (TX) beamformer (BF) that operates as a programmable digital pipeline, which enables steering of arbitrary pulse-density modulated (PDM) waveforms. The TX BF drives element-level 65 V unipolar pulsers, which in turn drive the CMUT array. Both the TX BF and RX μBF are programmed with shift-registers (SRs) that can either be programmed in a row-column fashion for fast upload times, or daisy-chain fashion for a higher flexibility. The layout of the ASICs is matched to the 365-μm-pitch monolithically-integrated CMUT array. While operating, the RX and logic power consumption per element is 0.85 and 0.10 mW, respectively. TX power consumption is highly waveform dependent, but is nominally 0.34 mW. Compared to the prior art, the probe has the highest volume rate, and features among the largest imaging arrays (both in terms of element-count and aperture) with a high flexibility in defining the TX waveform. These properties make it a suitable option for applications requiring HVR imaging of a large region of interest.

  2. A 2000-Volumes/s 3D Ultrasound Imaging Chip with Monolithically-Integrated 11.7x23.4mm² 2048-Element CMUT Array and Arbitrary-Wave TX Beamformer
    Nuriel M. Rozsa; Zhao Chen; Taehoon Kim; Peng Guo; Yannick Hopf; Jason Voorneveld; Djalma Simoes dos Santos; Emile Noothout; Zu-Yao Chang; Chao Chen; Vincent A. Henneken; Nico de Jong; Hendrik J. Vos; Johan G. Bosch; Martin D. Verweij; Michiel A. P. Pertijs;
    In Dig. Techn. Paper IEEE Symposium on VLSI Circuits (VLSI),
    IEEE, pp. 1--2, June 2024. DOI: 10.1109/VLSITechnologyandCir46783.2024.10631363

  3. A 3D Ultrasound Probe with Monolithically-Integrated 4096-Element CMUT Array Imaging 60° x 60° x 10cm at 2000 Volumes/s
    Nuriel N. M. Rozsa; Zhao Chen; Taehoon Kim; Peng Guo; Yannick Hopf; Jason Voorneveld; Djalma Simoes dos Santos; Emile Noothout; Zu-Yao Chang; Chao Chen; Vincent A. Henneken; Nico de Jong; Hendrik J. Vos; Johan G. Bosch; Martin D. Verweij; Michiel A. P. Pertijs;
    In Annual Workshop on Circuits, Systems and Signal Processing (ProRISC),
    July 2024.

  4. A 3D Ultrasound Probe with Monolithically-Integrated 4096-Element CMUT Array Imaging 60° x 60° x 10cm at 2000 Volumes/s
    Nuriel N. M. Rozsa; Zhao Chen; Taehoon Kim; Peng Guo; Yannick Hopf; Jason Voorneveld; Djalma Simoes dos Santos; Emile Noothout; Zu-Yao Chang; Chao Chen; Vincent A. Henneken; Nico de Jong; Hendrik J. Vos; Johan G. Bosch; Martin D. Verweij; Michiel A. P. Pertijs;
    In Proc. IEEE International Ultrasonics Symposium (IUS),
    IEEE, September 2024. abstract, Best Student Paper Award.

  5. A Pitch-Matched High-Frame-Rate Ultrasound Imaging ASIC for Catheter-Based 3D Probes
    Yannick M. Hopf; Djalma Simoes dos Santos; Boudewine W. Ossenkoppele; Mehdi Soozande; Emile Noothout; Zu-Yao Chang; Chao Chen; Hendrik J. Vos; Johan G. Bosch; Martin D. Verweij; Nico de Jong; Michiel A. P. Pertijs;
    IEEE Journal of Solid-State Circuits,
    Volume 59, Issue 2, pp. 476--491, February 2023. DOI: 10.1109/JSSC.2023.3299749
    Abstract: ... This article presents an application-specific integrated circuit (ASIC) for catheter-based 3-D ultrasound imaging probes. The pitch-matched design implements a comprehensive architecture with high-voltage (HV) transmitters, analog front ends, hybrid beamforming analog-to-digital converters (ADCs), and data transmission to the imaging system. To reduce the number of cables in the catheter while maintaining a small footprint per element, transmission (TX) beamforming is realized on the chip with a combination of a shift register (SR) and a row/column (R/C) approach. To explore an additional cable-count reduction in the receiver part of the design, a channel with a combination of time-division multiplexing (TDM), subarray beamforming, and multi-level pulse amplitude modulation (PAM) data transmission is also included. This achieves an 18-fold cable-count reduction and minimizes the power consumption in the catheter by a load modulation (LM) cable driver. It is further explored how common-mode interference can limit beamforming gain and a strategy to reduce its impact with local regulators is discussed. The chip was fabricated in TSMC 0.18-μm HV BCD technology and a 2-D PZT transducer matrix of 16 × 18 elements with a pitch of 160 μm and a center frequency of 6 MHz was manufactured on the chip. The system can generate all required TX patterns at up to 30 V, provides quick settling after the TX phase, and has an reception (RX) power consumption of only 1.12 mW/element. The functionality and operation of up to 1000 volumes/s have been demonstrated in electrical and acoustic imaging experiments.

  6. A Pitch-Matched Transceiver ASIC with Shared Hybrid Beamforming ADC for High-Frame-Rate 3D Intracardiac Echocardiography
    Yannick M. Hopf; Boudewine W. Ossenkoppele; Mehdi Soozande; Emile Noothout; Zu-Yao Chang; Chao Chen; Hendrik J. Vos; Johan G. Bosch; Martin D. Verweij; Nico de Jong; Michiel A. P. Pertijs;
    IEEE Journal of Solid-State Circuits,
    Volume 57, Issue 11, pp. 3228--3242, November 2022. DOI: 10.1109/jssc.2022.3201758
    Abstract: ... In this article, an application-specific integrated circuit (ASIC) for 3-D, high-frame-rate ultrasound imaging probes is presented. The design is the first to combine element-level, high-voltage (HV) transmitters and analog front-ends, subarray beamforming, and in-probe digitization in a scalable fashion for catheter-based probes. The integration challenge is met by a hybrid analog-to-digital converter (ADC), combining an efficient charge-sharing successive approximation register (SAR) first stage and a compact single-slope (SS) second stage. Application in large ultrasound imaging arrays is facilitated by directly interfacing the ADC with a charge-domain subarray beamformer, locally calibrating interstage gain errors and generating the SAR reference using a power-efficient local reference generator. Additional hardware-sharing between neighboring channels ultimately leads to the lowest reported area and power consumption across miniature ultrasound probe ADCs. A pitch-matched design is further enabled by an efficient split between the core circuitry and a periphery block, the latter including a datalink performing clock data recovery (CDR) and time-division multiplexing (TDM), which leads to a 12-fold total channel count reduction. A prototype of 8×9 elements was fabricated in a TSMC 0.18- μm HV BCD technology and a 2-D PZT transducer matrix with a pitch of 160μm , and a center frequency of 6 MHz was manufactured on the chip. The imaging device operates at up to 1000 volumes/s, generates 65-V transmit pulses, and has a receive power consumption of only 1.23 mW/element. The functionality has been demonstrated electrically as well as in acoustic and imaging experiments.

  7. Transceiver ASIC Design for High-Frame-Rate 3D Intracardiac Echocardiography
    Yannick M. Hopf; Boudewine Ossenkoppele; Mehdi Soozande; Emile Noothout; Zu-Yao Chang; Chao Chen; Hendrik J. Vos; Johan G. Bosch; Martin D. Verweij; Nico de Jong; Michiel A. P. Pertijs;
    In Proc. IEEE International Ultrasonics Symposium (IUS),
    2022.

  8. Front-End ASICs for 3-D Ultrasound: From Beamforming to Digitization
    Chao Chen;
    PhD thesis, Delft University of Technology, April 2018.

  9. Energy-Efficient Self-Timed Zero-Crossing-Based Incremental Delta-Sigma ADC
    Chao Chen;
    MSc thesis, Delft University of Technology, November 2012.
    document

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