With the continuous deepening of ocean exploration and the growth of emergency rescue needs, the hydroacoustic transducer, as an important component of sonar, has become more and more demanding. To improve the reception performance of the piezoelectric transducer, we developed a high-frequency, high-sensitivity planar piezoelectric transducer. A variant 1-3-2 type piezoelectric material is used to improve the effective electromechanical coupling coefficient, the upper surface of the material is covered with a brass plate to amplify the reception stress, and two variant 1-3-2 type piezoelectric materials with different dimensional parameters are arranged vertically to expand the bandwidth. We investigated the material properties and determined the material dimensions actually used to fabricate a planar hydroacoustic transducer utilizing electromechanical equivalent circuit analysis methods and finite element simulations. A prototype planar hydroacoustic transducer was fabricated and tested for resonant frequency, receiver sensitivity, bandwidth, and horizontal directivity then. The results show that the transducer’s resonant frequency is about 218.7kHz, the maximum receiving sensitivity is -178.7dB, the 3dB loss receiving bandwidth is about 45kHz, and the horizontal directivity is about 17°. The test results all indicate that the developed hydroacoustic transducer has great potential for application in marine exploration and underwater emergency rescue.
In this paper, a Code-Jump (CJ) assisted Least Mean Square (LMS) calibration algorithm for high resolution successive approximation register (SAR) analog-to-digital converter (ADC) is proposed. This hybird algorithm does not require any specific input signal and has no impact on the ADC overall gain error. The revised LMS iteration algorithm is used to improve the accuracy of the lowest bits (LSBs) capacitor in the capacitive-digital-to-analog converter (CDAC), and the calibrated LSBs segment is used as reference capacitor to complete CJ calibration scheme. According to the results of 2000 Monte Carlo simulations, compared to the pre-calibration results, the hybrid CJ-LMS calibration method significantly improves the mean value of SNDR, increasing from 58.2dB to 70.6dB, while simultaneously reducing the sigma of the SNDR distribution from 3.1dB to 0.3dB.
Accurate prediction of the remaining useful life (RUL) of metal oxide semiconductor field effect transistors (MOSFETs) is the key to safe and reliable operation of power electronics. In this paper, we combine long short-term memory (LSTM) networks with successive variational mode decomposition (SVMD) and use error compensation methods to build a lifetime prediction model, which improves the performance of the prediction model by reducing the interaction between different sequences and using error sequence compensation. The results show that, compared with the Bayesian optimized LSTM, the method has the advantages of high prediction accuracy and low prediction uncertainty.
A novel high precision and high PSRR bandgap voltage reference with improved high-order temperature compensation is proposed in this paper. An accurate curvature compensation topology is designed to compensate the reference voltage in the high and low temperature sections respectively. A pre-regular circuit is deployed to improve the PSRR and enlarge input voltage range. Implemented with TSMC 0.18um process, this design achieves an ultra-low temperature coefficient (TC) of 1.166ppm/°C from -40°C to 125°C with a high PSRR of -80dB at 1KHz.