A 4-channel Fully Integrated Ultrasound Imaging Front-End Transceiver for 1-D PMUT Arrays

This paper reports on the development of a fully integrated 4-channel analog front-end (AFE) transceiver designed for 1-D PMUT arrays operating in the 1-10 MHz range. The single channel consisted of a transceiver featuring a transmit (TX) pulser capable of delivering 100 mathbf{V}-{mathbf{pk}-mathbf{pk}}, 3-level pulses with independently programmable delay and duration followed by a T/R switch, and a receive (RX) chain comprising a programmable gain Low Noise voltage Amplifier (LNA) and a Buffer. Chip prototypes were fabricated using a 165nm BCD-SOI technology. Electrical and acoustic tests of the AFE were carried out in conjunction with a 2.5MHz, 80% fractional bandwidth, 64-element 1-D PMUT array fabricated using a sol-gel PZT thin film-based technology. Hydrophone and pulse-echo experiments were carried out in a water tank setup using a custom designed test board. Electrical characterization of the LNA reported a 0.65-40 MHz -3dB band, an equivalent input noise voltage density of 13 mathbf{nV}/surd Hz at 3 MHz at the maximum gain, and a power consumption of 5.4 mW/ch. The large signal TX pressure response of 4 adjacent PMUT array elements driven by 20Vpk, 3-cycle, 2MHz pulses was estimated at the transducer surface, resulting in a peak negative pressure of 543 kPa with a second harmonic distortion of -30 dB. Small signal TX pressure and pulse-echo impulse responses were processed to extract the transfer function of the RX chain, which is characterized by a peak sensitivity of 55 mV/ kPa at 2.3 MHz.