A Pixel Pitch-Matched Ultrasound Receiver for 3-D Photoacoustic Imaging With Integrated Delta-Sigma Beamformer in 28-nm UTBB FD-SOI

• Published in: IEEE journal of solid-state circuits Vol. 52; no. 11; pp. 2843 - 2856
• Main Authors: Chen, Man-Chia, Pena Perez, Aldo, Kothapalli, Sri-Rajasekhar, Cathelin, Philippe, Cathelin, Andreia, Gambhir, Sanjiv Sam, Murmann, Boris
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.11.2017
• Subjects: 3-D photoacoustic (PA) imaging; analog-to-digital conversion (ADC); Array signal processing; capacitive micromachined ultrasound transducer (CMUT); Clocks; CMOS; Delays; delta-sigma modulation; ENGINEERING; FDSOI; Imaging; matrix transducer array; OTHER INSTRUMENTATION; Receivers; Signal to noise ratio; subarray beamforming; Transducers; ultrasound (US); delta-sigma modulation; CMOS; capacitive micromachined ultrasound transducer (CMUT); matrix transducer array; analog-to-digital conversion (ADC); FDSOI; ultrasound (US); subarray beamforming; 3-D photoacoustic (PA) imaging
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2017.2749425

This paper presents a pixel pitch-matched readout chip for 3-D photoacoustic (PA) imaging, featuring a dedicated signal conditioning and delta-sigma modulation integrated within a pixel area of 250 μm by 250 μm. The proof-of-concept receiver was implemented in an STMicroelectronics's 28-nm Fully Depleted Silicon On Insulator technology, and interfaces to a 4 × 4 subarray of capacitive micromachined ultrasound transducers (CMUTs). The front-end signal conditioning in each pixel employs a coarse/fine gain tuning architecture to fulfill the 90-dB dynamic range requirement of the application. The employed delta-sigma beamforming architecture obviates the need for area-consuming Nyquist ADCs and thereby enables an efficient in-pixel A/D conversion. The per-pixel switched-capacitor ΔΣ modulator leverages slewing-dominated and area-optimized inverter-based amplifiers. It occupies only 1/4th of the pixel, and its area compares favorably with state-of-the-art designs that offer the same SNR and bandwidth. The modulator's measured peak signal-to-noise-and-distortion ratio is 59.9 dB for a 10-MHz input bandwidth, and it consumes 6.65 mW from a 1V supply. The overall subarray beamforming approach improves the area per channel by 7.4 times and the single-channel SNR by 8 dB compared to prior art with similar delay resolution and power dissipation. The functionality of the designed chip was evaluated within a PA imaging experiment, employing a flip-chip bonded 2-D CMUT array.