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Multilayer 2-D array transducers with integrated circuit transmitters and receivers: a feasibility study

In 2-D arrays, the elements have poor signal-to-noise ratio (SNR) because their small size results in a small clamped capacitance and a large electrical impedance near resonance. The SNR can be increased using multi-layer PZT transducers. It is hypothesized that further improvements in pulse-echo SNR are obtained using a hybrid array in the following configuration: in the transmit mode, 10 Ω electronic transmitters exciting 10 Ω multi-layer elements, and in the receive mode, single layer elements driving high impedance pre-amplifiers. A sparsely sampled array was modeled, operating at 7.5 MHz. According to simulations, pulse-echo SNR was improved by 40 dB in the hybrid configuration compared to the control. An experimental feasibility study was also performed using a 2.25 MHz transducer. The measurements were consistent with the simulations. The dramatic improvement in SNR for the hybrid configuration allows for new implementations of the transmit and receive circuitry