MSc E. Kang

1. A Readout IC for Capacitive Touch Screen Panels with 33.9 dB Charge-Overflow Reduction Using Amplitude-Modulated Multi-Frequency Excitation
   J.-S. An; J.-H. Ra; E. Kang; M. Pertijs; S.-H. Han;
   IEEE Journal of Solid-State Circuits,
   Volume 56, Issue 11, pp. 3486-3498, November 2021. DOI: 10.1109/JSSC.2021.3100470
   
   Abstract: ...

   This paper presents a readout integrated circuit (ROIC) for capacitive touch-screen panels employing an amplitude-modulated multiple-frequency excitation (AM-MFE) technique. To prevent charge overflow, which occurs periodically at the beat frequency of the excitation frequencies, the ROIC modulates the amplitude of the excitation voltages at a mixing frequency derived from the excitation frequencies. Thus, the ROIC can sense the charge signal without charge overflow and maximize the signal-to-noise ratio (SNR) by increasing the amplitude of the excitation voltages up to the sensing range of the readout circuit. The proposed ROIC was fabricated in a 0.13-µm standard CMOS process and was measured with a 32-inch 104×64 touch-screen panel using 1 mm and 10 mm metal pillars. It reduces charge overflow up to 33.9 dB compared to operation without AM-MFE. In addition, the ROIC achieves a frame rate of 2.93 kHz, and SNRs of 41.7 dB and 61.6 dB with 1 mm and 10 mm metal pillars, respectively.

2. A Transceiver ASIC for a Single-Cable 64-Element Intra-Vascular Ultrasound Probe
   D. van Willigen; J. Janjic; E. Kang; Z. Y. Chang; E. Noothout; M. Verweij; N. de Jong; M. Pertijs;
   IEEE Journal of Solid-State Circuits,
   Volume 56, Issue 10, pp. 3157-3166, October 2021. DOI: 10.1109/jssc.2021.3083217
   
   Abstract: ...

   This article presents an application-specific integrated circuit (ASIC) designed for intra-vascular ultrasound imaging that interfaces 64 piezoelectric transducer elements to an imaging system using a single micro-coaxial cable. Thus, it allows a single-element transducer to be replaced by a transducer array to enable 3-D imaging. The 1.5-mm-diameter ASIC is intended to be mounted at the tip of a catheter, directly integrated with a 2-D array of piezoelectric transducer elements. For each of these elements, the ASIC contains a high-voltage (HV) switch, allowing the elements to transmit an acoustic wave in response to an HV pulse generated by the imaging system. A low-noise amplifier then amplifies the resulting echo signals and relays them as a signal current to the imaging system, while the same cable provides a 3-V supply. Element selection and other settings can be programmed by modulating configuration data on the supply, thus enabling full synthetic aperture imaging. An integrated element test mode measures the element capacitance to detect bad connections to the transducer elements. The ASIC has been fabricated in a 0.18-μm HV CMOS technology and consumes only 6 mW in receive. Electrical measurements show correct switching of 30-V transmit pulses and a receive amplification with a 71-dB dynamic range, including 12 dB of programmable gain over a 3-dB bandwidth of 21 MHz. The functionality of the ASIC has been successfully demonstrated in a 3-D imaging experiment.

3. Low Leakage and High Forward Current Density Quasi-Vertical GaN Schottky Barrier Diode With Post-Mesa Nitridation
   X. Kang; Y. Sun; Y. Zheng; K. Wei; H. Wu; Y. Zhao; Xu Liu; GuoQi Zhang;
   IEEE Transactions on Electron Devices,
   Volume 68, Issue 3, pp. 1369-1373, 2021. DOI: 10.1109/TED.2021.3050739

4. A 64-Channel Transmit Beamformer with ±30V Bipolar High-Voltage Pulsers for Catheter-Based Ultrasound Probes
   M. Tan; E. Kang; J.-S. An; Z. Y. Chang; P. Vince; T. Matéo; N. Sénégond; M. A. P. Pertijs;
   IEEE Journal of Solid-State Circuits,
   Volume 55, Issue 7, pp. 1796-1806, July 2020. DOI: 10.1109/JSSC.2020.2987719
   
   Abstract: ...

   This article presents a fully integrated 64-channel programmable ultrasound transmit beamformer for catheter-based ultrasound probes, designed to interface with a capacitive micro-machined ultrasound transducer (CMUT) array. The chip is equipped with programmable high-voltage (HV) pulsers that can generate ±30-V return-to-zero (RZ) and non-RZ pulses. The pulsers employ a compact back-to-back isolating HV switch topology that employs HV floating-gate drivers with only one HV MOS transistor each. Further die-size reduction is achieved by using the RZ switches also as the transmit/receive (T/R) needed to pass received echo signals to low-voltage receive circuitry. On-chip digital logic clocked at 200 MHz allows the pulse timing to be programmed with a resolution of 5 ns, while supporting pulses of 1 cycle up to 63 cycles. The chip has been implemented in 0.18-μm HV Bipolar-CMOS-DMOS (BCD) technology and occupies an area of 1.8 mm x 16.5 mm, suitable for integration into an 8-F catheter. Each pulser with embedded T/R switch and digital logic occupies only 0.167 mm². The pulser successfully drives an 18-pF transducer capacitance at pulse frequencies up to 9 MHz. The T/R switch has a measured ON-resistance of ~180 Ω . The acoustic results obtained in combination with a 7.5-MHz 64-element CMUT array demonstrate the ability to generate steered and focused acoustic beams.

5. A Variable-Gain Low-Noise Transimpedance Amplifier for Miniature Ultrasound Probes
   E. Kang; M. Tan; J. S. An; Z. Y. Chang; P. Vince; N. Sénégond; T. Mateo; C. Meynier; M. A. P. Pertijs;
   IEEE Journal of Solid-State Circuits,
   Volume 55, Issue 12, pp. 3157--3168, December 2020. DOI: 10.1109/jssc.2020.3023618
   
   Abstract: ...

   This article presents a low-noise transimpedance amplifier (TIA) designed for miniature ultrasound probes. It provides continuously variable gain to compensate for the time-dependent attenuation of the received echo signal. This time-gain compensation (TGC) compresses the echo-signal dynamic range (DR) while avoiding imaging artifacts associated with discrete gain steps. Embedding the TGC function in the TIA reduces the output DR, saving power compared to prior solutions that apply TGC after the low-noise amplifier. The TIA employs a capacitive ladder feedback network and a current-steering circuit to obtain a linear-in-dB gain range of 37 dB. A variable-gain loop amplifier based on current-reuse stages maintains constant bandwidth in a power-efficient manner. The TIA has been integrated in a 64-channel ultrasound transceiver application-specific integrated circuit (ASIC) in a 180-nm BCDMOS process and occupies a die area of 0.12 mm². It achieves a gain error below ±1 dB and a 1.7 pA/√ Hz noise floor and consumes 5.2 mW from a ±0.9 V supply. B-mode images of a tissue-mimicking phantom are presented that show the benefits of the TGC scheme.

6. Optimization of Mesa Etch for a Quasi-Vertical GaN Schottky Barrier Diode (SBD) by Inductively Coupled Plasma (ICP) and Device Characteristics
   Yue Sun; Xuanwu Kang; Yingkui Zheng; Ke Wei; Pengfei Li; Wenbo Wang; Xinyu Liu; GuoQi Zhang;
   Nanomaterials,
   Volume 10, Issue 4, pp. 657, Apr 2020. DOI: 10.3390/nano10040657
   document

7. P-type β-Ga2O3 metal-semiconductor-metal solar-blind photodetectors with extremely high responsivity and gain-bandwidth product
   Z.X. Jiang; Z.Y. Wu; C.C. Ma; J.N. Deng; H. Zhang; Y. Xu; J.D. Ye; Z.L. Fang; GuoQi Zhang; J.Y. Kang; T.-Y. Zhang;
   Materials Today Physics,
   Volume 14, pp. 100226, 2020. DOI: 10.1016/j.mtphys.2020.100226
   document

8. A Capacitive Touch Chipset with 33.9dB Charge-Overflow Reduction using Amplitude-Modulated Multi-Frequency Excitation and Wireless Power and Data Transfer to an Active Stylus
   J.-S. An; J.-H. Ra; E. Kang; M. Pertijs; S.-H. Han;
   In Dig. Techn. Papers IEEE International Solid-State Circuits Conference (ISSCC),
   pp. 430-431, February 2020.

9. A 2 pA/√Hz Transimpedance Amplifier for Miniature Ultrasound Probes with 36dB Continuous Time-Gain Compensation
   E. Kang; M. Tan; J. An; P. Vince; N. Sénégond; T. Mateo; Cyril Meynier; M. A. P. Pertijs;
   In Dig. Techn. Papers IEEE International Solid-State Circuits Conference (ISSCC),
   pp. 354-355, February 2020.

10. A 12×80 Element Ultrasound Transceiver ASIC With Enhanced Charge Injection Performance for 3-D Carotid Artery Imaging
    T. Kim; F. Fool; E. Kang; Z. Y. Chang; E. Noothout; J. G. Bosch; M. D. Verweij; N. de Jong; M. Pertijs;
    In Proc. IEEE International Ultrasonics Symposium (IUS),
    September 2020. abstract.

11. A 1-D CMUT Transducer with Front-end ASIC in a 9 French Catheter for Intracardiac Echocardiography: Acoustic and Imaging Evaluation
    T. Matéo; P. Vince; N. Sénégond; M. Tan; E. Kang; M. Pertijs;
    In Proc. IEEE International Ultrasonics Symposium (IUS),
    September 2020. DOI: 10.1109/IUS46767.2020.9251715
    
    Abstract: ...

    In this work, we report the acoustical characterization of a 9 French (Fr) CMUT-based 1D catheter tip (2.5×12.8 mm2 - 64 elements - 7.5 MHz) embedding a 64 channels analog transceiver ASIC (180 nm HV BCD technology) dedicated to Intra-cardiac Echocardiography. To this end, a Through-Silicon-Via process has been integrated in the CMUT process flow to ensure suitable vertical integration level needed to accommodate with the catheter's form factor. Good overall functioning of essential ASIC functionalities with the CMUT, i.e. transmit, beamforming, and receive, is first reported, starting from elementary characterization up to imaging. Additionally, a comparison with a custom discrete solution based on Commercial Off-The-Shelf components (COTS) to provide suitable CMUT preamplification in receive is performed. Using the same CMUT chip either with the ASIC, either with the COTS, allowed to quantify the benefit brought by the ASIC compared to a more straightforward but less integrated solution. Main results highlight that CMUT-on-ASIC allows to recover a much wider bandwidth (BW), increasing by 3 MHz the -6dB upper limit, and therefore getting closer the theoretical BW of the CMUT itself. Moreover, lower element crosstalk is measured on CMUT-on-ASIC device, showing that the ASIC decreases the electrical coupling compared to the COTS. Finally, noise equivalent pressure measurements in comparison with simulations in realistic ICE configuration promise much higher receive sensitivity with the ASIC solution, hence, confirming its great interest for the CMUT technology compared to less integrated solution, especially for catheter application.

12. 3D High Frame Rate Imaging Scheme for Ultrasound Carotid Imaging
    M. Soozande; M. Mozzaffarzadeh; F. Fool; T. Kim; E. Kang; M. Pertijs; M. Verweij; H. J. Vos; J. G. Bosch; N. de Jong;
    In Proc. IEEE International Ultrasonics Symposium (IUS),
    September 2020. abstract.

13. An Integrated Programmable High-Voltage Bipolar Pulser with Embedded Transmit/Receive Switch for Miniature Ultrasound Probes
    M. Tan; E. Kang; J.-S. An; Z. Y. Chang; P. Vince; N. Sénégond; M. A. P. Pertijs;
    IEEE Solid-State Circuits Letters,
    Volume 2, Issue 9, pp. 79-82, September 2019. DOI: 10.1109/LSSC.2019.2938141
    
    Abstract: ...

    This letter presents a compact programmable high-voltage (HV) pulser for ultrasound imaging, designed for driving capacitive micromachined ultrasonic transducers (CMUTs) in miniature ultrasound probes. To enable bipolar return-to-zero (RZ) pulsing and embedded transmit/receive switching, a compact back-to-back isolating HV switch is proposed that employs HV floating-gate drivers with only one HV MOS transistor each. The pulser can be digitally programmed to generate bipolar pulses with and without RZ, with a peak-to-peak swing up to 60 V, as well as negative and positive unipolar pulses. It can generate bursts of up to 63 pulses, with a maximum pulse frequency of 9 MHz for an 18-pF transducer capacitance. Realized in TSMC 0.18um HV BCD technology, the pulser occupies only 0.167mm2 . Electrical characterization results of the pulser, as well as acoustic results obtained in the combination with a 7.5-MHz CMUT transducer, are presented.

14. Review of the recent progress on GaN-based vertical power Schottky barrier diodes (SBDs)
    Yue Sun; Kang, X.; Zheng, Y.; Lu, J.; Tian, X.; Wei, K.; Wu, H.; Wang, W.; Liu, X. an GuoQi Zhang;
    Electronics (Switzerland),
    2019. DOI: 10.3390/electronics8050575

15. 3D high frame rate flow measurement using a prototype matrix transducer for carotid imaging
    F. Fool; H. J. Vos; M. Shabanimotlagh; T. Kim; E. Kang; M. Pertijs; N. de Jong; M. D. Verweij;
    In Proc. IEEE International Ultrasonics Symposium (IUS),
    IEEE, pp. 1-4, October 2019.

16. An Integrated Programmable High-Voltage Bipolar Pulser with Embedded Transmit/Receive Switch for Miniature Ultrasound Probes
    M. Tan; E. Kang; J.-S. An; Z. Y. Chang; P. Vince; N. Sénégond; M. A. P. Pertijs;
    In Proc. European Solid-State Circuits Conference (ESSCIRC),
    pp. 325--328, October 2019.
    
    Abstract: ...

    This paper presents a compact programmable high-voltage (HV) pulser for ultrasound imaging, designed for driving capacitive micro-machined ultrasonic transducers (CMUTs) in miniature ultrasound probes. To enable bipolar return-to-zero pulsing and embedded transmit/receive switching, a compact back-to-back isolating HV switch is proposed that employs HV floating-gate drivers with only one HV MOS transistor each. The pulser can be digitally programmed to generate bipolar pulses with and without return-to-zero, with a peak-to-peak swing up to 60 V, as well as negative and positive unipolar pulses. It can generate bursts of up to 63 pulses, with a maximum pulse frequency of 9 MHz for an 18 pF transducer capacitance. Realized in TSMC 0.18 μm HV BCD technology, the pulser occupies only 0.167 mm2. Electrical characterization results of the pulser, as well as acoustic results obtained in combination with a 7.5-MHz CMUT transducer, are presented.

17. Amplifier with continuous gain control
    M. A. P. Pertijs; E. Kang;
    Patent, WO2021/015618A2, July 2019.

18. A Reconfigurable Ultrasound Transceiver ASIC With 24 × 40 Elements for 3D Carotid Artery Imaging
    E. Kang; Q. Ding; M. Shabanimotlagh; P. Kruizinga; Z. Y. Chang; E. Noothout; H. J. Vos; J. G. Bosch; M. D. Verweij; N. de Jong; M. A. P. Pertijs;
    IEEE Journal of Solid-State Circuits,
    Volume 53, Issue 7, pp. 2065-2075, July 2018. DOI: 10.1109/JSSC.2018.2820156
    
    Abstract: ...

    This paper presents an ultrasound transceiver application-specific integrated circuit (ASIC) designed for 3-D ultrasonic imaging of the carotid artery. This application calls for an array of thousands of ultrasonic transducer elements, far exceeding the number of channels of conventional imaging systems. The 3.6 x 6.8 mm² ASIC interfaces a piezo-electric transducer (PZT) array of 24 x 40 elements, directly integrated on top of the ASIC, to an imaging system using only 24 transmit and receive channels. Multiple ASICs can be tiled together to form an even bigger array. The ASIC, implemented in a 0.18 μm high-voltage (HV) BCD process, consists of a reconfigurable switch matrix and row-level receive circuits. Each element is associated with a compact bootstrapped HV transmit switch, an isolation switch for the receive circuits and programmable logic that enables a variety of imaging modes. Electrical and acoustic experiments successfully demonstrate the functionality of the ASIC. In addition, the ASIC has been successfully used in a 3-D imaging experiment.

19. ASIC design for a single-cable 64-element ultrasound probe
    D. van Willigen; J. Janjic; E. Kang; Z. Y. Chang; E. Noothout; M. Verweij; N. de Jong; M. Pertijs;
    In Proc. IEEE International Ultrasonics Symposium (IUS),
    IEEE, pp. 1-4, October 2018.
    
    Abstract: ...

    This paper presents an ASIC (Application Specific Integrated Circuit) design for a catheter probe that interfaces 64 piezoelectric elements directly integrated on top of the ASIC to an imaging system using a single micro-coaxial cable. Each of the piezo elements can be used for both transmit (TX) and receive (RX), enabling full synthetic aperture imaging. A prototype has been realized with a 1.5mm diameter circular layout, intended for 3D intra-vascular ultrasound imaging. The functionality of this ASIC has been successfully demonstrated in a 3D imaging experiment. The design allows a single-element transducer to be replaced by a transdcuer array while using the same cable, making it a promising solution for 3D imaging with size constrained probes.

20. A Power-Efficient Transmit Beamformer ASIC for 3-D Catheter-Based/ Endoscopic Probes
    Z. Chen; E. Kang; Z. Y. Chang; E. Noothout; J. G. Bosch; M. Verweij; N. de Jong; M. Pertijs;
    In Proc. IEEE International Ultrasonics Symposium (IUS),
    IEEE, October 2018. (abstract).
    
    Abstract: ...

    To reduce cable count in 3D catheter-based or endoscopic probes, generation of the (HV) transmit (TX) signals using an in-probe ASIC is a promising solution. However, such ASICs are subject to stringent power-consumption constraints to limit self-heating. The power consumed by conventional HV pulsers is at least fCV^2, due to the periodic charging/discharging of the transducer element capacitance C. HV switches can be used to connect elements to a pulser in the imaging system, thus only dissipating a fraction of fCV^2 in the probe, but full TX beamforming (BF) cannot be realized using switches. In this work, we propose a power-efficient HV TX circuit capable of providing full TX BF using only 3 HV connections to the system. Implemented in a 0.18um BCD process, the ASIC was fully evaluated by means of post-layout simulations.

21. A Reconfigurable 24 × 40 Element Transceiver ASIC for Compact 3D Medical Ultrasound Probes
    E. Kang; Q. Ding; M. Shabanimotlagh; P. Kruizinga; Z. Y. Chang; E. Noothout; H. J. Vos; J. G. Bosch; M. D. Verweij; N. de Jong; M. A. P. Pertijs;
    In Proc. European Solid-State Circuits Conference (ESSCIRC),
    IEEE, pp. 211-214, September 2017.

22. Towards 3D ultrasound imaging of the carotid artery using a programmable and tileable matrix array
    P. Kruizinga; E. Kang; M. Shabanimotlagh; Q. Ding; E. Noothout; Z. Y. Chang; H. J. Vos; J. G. Bosch; M. D. Verweij; M. A. P. Pertijs; N. de Jong;
    In Proc. IEEE International Ultrasonics Symposium (IUS),
    IEEE, pp. 1-3, September 2017. DOI: 10.1109/ULTSYM.2017.8091570
    
    Abstract: ...

    Accurate assessment of carotid artery disease by measuring blood flow, plaque deformation and pulse wave velocity using ultrasound imaging requires 3D information. Additionally, the volume rates should be high enough (> 1 kHz) to capture the full range of these fast transient phenomena. For this purpose, we have built a programmable, tileable matrix array that is capable of providing 3D ultrasound imaging at such volume rates. This array contains an application-specific integrated circuit (ASIC) right beneath the acoustic piezo-stack. The ASIC enables fast programmable switching between various configurations of elements connected to the acquisition system via a number of channels far smaller than the number of transducer elements. This design also allows for expanding the footprint by tiling several of these arrays together into one large array. We explain the working principles and show the first basic imaging results of a 2-by-1 tiled array.

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