AlN Piezoelectric Micromachined Ultrasonic Transducer Array Monolithically Fabricated on Top of Pre-Processed CMOS Substrates

Ledesma, Eyglis; Zamora, Iván; Torres, F.; Uranga, A.; Tzanov, Vassil; Barniol, N.; Marigo, E.; Soundara-Pandian, Mohan

doi:10.1109/transducers.2019.8808706

Cited by 10 publications

(6 citation statements)

References 5 publications

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“…The PMUT was modeled as a current source in parallel with its electrical capacitance. The assumed operation frequency was the resonance frequency of the PMUT array in liquid (3 MHz), which was given by Reference [10]. Figure 8 shows the transimpedance gain of both approaches (the voltage amplifier and charge-sensitive amplifier) and the voltage open-loop gain A 0 .…”

Section: Front-end Amplifier Simulation Resultsmentioning

confidence: 99%

“…The electrical capacitance of a single PMUT was estimated at around 200 fF, adding up to a total of 1.2 pF per row. The obtained resonance frequency in fluorinert (FC-70) was in the 3-MHz range, with a bandwidth around 1 MHz [10].…”

Section: Ultrasonic Transducermentioning

confidence: 96%

“…As proof of concept for the integrated front-end circuitry, an 80-µm/side AlN PMUT in a 6 × 6 array configuration was used [10]. The electrical capacitance of a single PMUT was estimated at around 200 fF, adding up to a total of 1.2 pF per row.…”

Section: Ultrasonic Transducermentioning

confidence: 99%

“…The transmitter circuit is in charge of the generation of a large voltage signal in order to excite the transducer at its resonance frequency (f r ) and provide enough acoustic pressure for a high signal-to-noise ratio in the echo measurements. We set the needed actuation voltage to a maximum voltage of 32 V to guarantee enough output pressure [10]. Additionally, and taking into account the fact that the square wave increases the effective amplitude 1.27 times compared to a sine wave, we chose a squared-wave transmitter circuit with a 32-V peak voltage and with rising and falling times less than 100 ns to guarantee at least a 50% duty cycle and a 3-MHz driving frequency (according to the expected PMUT resonance frequency in fluorinert).…”

Section: High-voltage Transmittermentioning

confidence: 99%

“…In order to perform good signal processing, at least 85% of the charge transfer must be guaranteed. Considering a C PMUT = 1.2 pF (equivalent to one row of six 80-µm PMUTs [10]), a parametric AC analysis was performed to compute the charge transfer. Figure 6 shows that for a C f higher than 400 fF, the amplifier behaves as a CSA and guarantees at least an 85% charge transfer.…”

Section: Charge-sensitive Amplifier (Csa) Descriptionmentioning

confidence: 99%

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Miniaturized 0.13-μm CMOS Front-End Analog for AlN PMUT Arrays

Zamora

Ledesma

Uranga

et al. 2020

Sensors

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This paper presents an analog front-end transceiver for an ultrasound imaging system based on a high-voltage (HV) transmitter, a low-noise front-end amplifier (RX), and a complementary-metal-oxide-semiconductor, aluminum nitride, piezoelectric micromachined ultrasonic transducer (CMOS-AlN-PMUT). The system was designed using the 0.13-μm Silterra CMOS process and the MEMS-on-CMOS platform, which allowed for the implementation of an AlN PMUT on top of the CMOS-integrated circuit. The HV transmitter drives a column of six 80-μm-square PMUTs excited with 32 V in order to generate enough acoustic pressure at a 2.1-mm axial distance. On the reception side, another six 80-μm-square PMUT columns convert the received echo into an electric charge that is amplified by the receiver front-end amplifier. A comparative analysis between a voltage front-end amplifier (VA) based on capacitive integration and a charge-sensitive front-end amplifier (CSA) is presented. Electrical and acoustic experiments successfully demonstrated the functionality of the designed low-power analog front-end circuitry, which outperformed a state-of-the art front-end application-specific integrated circuit (ASIC) in terms of power consumption, noise performance, and area.

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Section: Front-end Amplifier Simulation Resultsmentioning

confidence: 99%

Section: Ultrasonic Transducermentioning

confidence: 96%

Section: Ultrasonic Transducermentioning

confidence: 99%

Section: High-voltage Transmittermentioning

confidence: 99%

Section: Charge-sensitive Amplifier (Csa) Descriptionmentioning

confidence: 99%

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Miniaturized 0.13-μm CMOS Front-End Analog for AlN PMUT Arrays

Zamora

Ledesma

Uranga

et al. 2020

Sensors

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Monolithic Single PMUT-on-CMOS Ultrasound System With +17 dB SNR for Imaging Applications

et al. 2020

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This paper presents a fully integrated ultrasound system based on a single piezoelectric micromachined ultrasonic transducer (PMUT) monolithically fabricated with a 0.13 µm complementary metal oxide semiconductor (CMOS) process analog front-end circuitry. The PMUT consists of an aluminum nitride, AlN, squared device with 80 µm side that resonates at 2.4 MHz in liquid environment. The monolithic integration of the PMUT with the CMOS circuitry allows a reduction of the parasitic capacitance, a reduction of the electronic noise contribution and a clear improvement in the Signal-to Noise ratio (SNR ~ 27 dB better) compared to a non-integrated equivalent system. A pulse-echo experiment with the single PMUT-on-CMOS for transmitting and sensing simultaneously is demonstrated, ensuring a 17.3 dB SNR, higher than the minimal necessary for accurate fingerprint images, paving the way towards a pixel sized imaging system with no need of multiple simultaneous PMUTs transmitters. Consuming only 0.3 mW and getting an input-referred noise of 3.26 mPa/√Hz at 2.4 MHz, the proposed pulse-echo system achieves a competitive noise efficient factor in comparison with the state-of-the-art.

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