MSc Rozsa

1. Effect of SAR-ADC Non-Idealities on Medical Ultrasound B-Mode Imaging
   N. Radeljic-Jakic; A. Flikweert; Y. Hopf; N. Rozsa; M. Pertijs;
   In Proc. IEEE International Ultrasonics Symposium (IUS),
   2023. abstract, accepted.

2. A Tiled Ultrasound Matrix Transducer for Volumetric Imaging of the Carotid Artery
   dos Santos, Djalma Simões; Fool, Fabian; Mozaffarzadeh, Moein; Shabanimotlagh, Maysam; Noothout, Emile; Kim, Taehoon; Rozsa, Nuriel; Vos, Hendrik J.; Bosch, Johan G.; Pertijs, Michiel A. P.; Verweij, Martin D.; de Jong, Nico;
   Sensors,
   Volume 22, Issue 24, pp. 1--23, 2022. DOI: 10.3390/s22249799
   
   Abstract: ...

   High frame rate three-dimensional (3D) ultrasound imaging would offer excellent possibilities for the accurate assessment of carotid artery diseases. This calls for a matrix transducer with a large aperture and a vast number of elements. Such a matrix transducer should be interfaced with an application-specific integrated circuit (ASIC) for channel reduction. However, the fabrication of such a transducer integrated with one very large ASIC is very challenging and expensive. In this study, we develop a prototype matrix transducer mounted on top of multiple identical ASICs in a tiled configuration. The matrix was designed to have 7680 piezoelectric elements with a pitch of 300 μm × 150 μm integrated with an array of 8 × 1 tiled ASICs. The performance of the prototype is characterized by a series of measurements. The transducer exhibits a uniform behavior with the majority of the elements working within the −6 dB sensitivity range. In transmit, the individual elements show a center frequency of 7.5 MHz, a −6 dB bandwidth of 45%, and a transmit efficiency of 30 Pa/V at 200 mm. In receive, the dynamic range is 81 dB, and the minimum detectable pressure is 60 Pa per element. To demonstrate the imaging capabilities, we acquired 3D images using a commercial wire phantom.
   
   document

3. A Chopper Class-D Amplifier for PSRR Improvement Over the Entire Audio Band
   Huajun Zhang; Nuriel N. M. Rozsa; Marco Berkhout; Qinwen Fan;
   {IEEE} Journal of Solid-State Circuits,
   Volume 57, Issue 7, pp. 2035--2044, July 2022. DOI: 10.1109/jssc.2022.3161136
   document

4. Automated Characterization of Matrix Transducer Arrays using the Verasonics Imaging System
   Djalma Simoes dos Santos; Fabian Fool; Taehoon Kim; Emile Noothout; Nuriel Rozsa; Hendrik J. Vos; Johan G. Bosch; Michiel A. P. Pertijs; Martin D. Verweij; Nico de Jong;
   In Proc. IEEE International Ultrasonics Symposium (IUS),
   2022.

5. Automated Characterization of Matrix Transducer Arrays using the Verasonics Imaging System
   Djalma Simoes dos Santos; Fabian Fool; Taehoon Kim; Emile Noothout; Nuriel Rozsa; Hendrik J. Vos; Johan G. Bosch; Michiel A. P. Pertijs; Martin D. Verweij; Nico de Jong;
   In Proc. IEEE International Ultrasonics Symposium (IUS),
   2022.

6. A -109.1 dB/-98 dB THD/THD+N Chopper Class-D Amplifier with >83.7 dB PSRR Over the Entire Audio Band
   Huajun Zhang; Nuriel Rozsa; Marco Berkhout; Qinwen Fan;
   In ESSCIRC 2021 - IEEE 47th European Solid State Circuits Conference (ESSCIRC),
   United States, IEEE, pp. 395--398, 2021. Accepted author manuscript; ESSCIRC 2021 : IEEE 47th European Solid State Circuits Conference ; Conference date: 06-09-2021 Through 09-09-2021. DOI: 10.1109/ESSCIRC53450.2021.9567786
   
   Keywords: ...

   Class-D amplifier, PSRR, PWM, chopping, intermodulation.
   
   
   Abstract: ...

   This paper reports a chopper Class-D audio amplifier that obtains high PSRR over the entire audio band. A chopping scheme is proposed to minimize intermodulation distortion between pulse-width modulation (PWM) and chopping in the audio band. A high-voltage chopper is developed to handle a 14.4 V PWM signal. Timing matching techniques are proposed to minimize chopping nonidealities which ensure good PSRR and THD. Fabricated in a 180nm BCD process, the prototype obtains a PSRR >109 dB at 217 Hz and >83.7 dB over the entire audio band. It also achieves -109.1 dB/-98 dB THD/THD+N and can deliver a maximum of 13 W to an 8-Ω load.

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