dr. An

1. A Compact 10-MHz RC Frequency Reference With a Versatile Temperature Compensation Scheme
   Pan, Sining; An, Xiaomeng; Yu, Zheru; Jiang, Hui; Makinwa, Kofi A. A.;
   IEEE Journal of Solid-State Circuits,
   pp. 1-9, 2023. DOI: 10.1109/JSSC.2023.3322307

2. A 0.01 mm2 10MHz RC Frequency Reference with a 1-Point On-Chip-Trimmed Inaccuracy of 0.28% from −45°C to 125°C in 0.18μm CMOS
   An, Xiaomeng; Pan, Sining; Jiang, Hui; Makinwa, Kofi A. A.;
   In 2023 IEEE International Solid-State Circuits Conference (ISSCC),
   pp. 60-62, 2023. DOI: 10.1109/ISSCC42615.2023.10067530

3. 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.

4. A Low-Power Reconfigurable Transceiver ASIC for a CMUT-based Wearable Ultrasound Patch
   Mingliang Tan; Tim Hosman; Jae-Sung An; Zu-Yao Chang; Michiel Pertijs;
   In Annual Workshop on Circuits, Systems and Signal Processing (ProRISC),
   July 2021.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. 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.

11. A Low-Power ASIC with On-Chip Receive Digitization and Bipolar High-Voltage Transmitters for Wearable Ultrasound Devices
    Jae-Sung An; Mingliang Tan; Michiel Pertijs;
    In Annual Workshop on Circuits, Systems and Signal Processing (ProRISC),
    July 2019. poster.

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