Development of Radiation Hard N+-on-P Silicon Microstrip Sensors for Super LHC

Radiation tolerance up to 1015 1-MeV neq/cm2 is required for the silicon microstrip sensors to be operated at the Super LHC experiment. As a candidate for such sensors, we are investigating non-inverting n+-on-p sensors. We manufactured sample sensors of 1 times 1 cm in 4" and 6" processes with implementing different interstrip electrical isolation structures. Industrial high resistive p-type wafers from FZ and MCZ growth are tested. They are different in crystal orientations lang100rang and lang111rang with different wafer resistivities. The sensors were irradiated with 70-MeV protons and characterized in views of the leakage current increase, noise figures, electrical strip isolation, full depletion voltage evolution, and charge collection efficiency

Compensation for Nonlinear Distortion of the Frequency Modulation-Based Parametric Array Loudspeaker

The parametric array loudspeaker (PAL) modulates the audio signal on an ultrasonic carrier. When the modulated signal is transmitted in air, an audio beam is created based on the nonlinear acoustic principle. Each modulation method has advantages and disadvantages. The frequency modulation (FM) is favorable for its low cost and high volume, but the tradeoff is its complicated nonlinear distortion, which is difficult to be reduced. In this paper, the Volterra filter is adopted to model the nonlinearity of the FM-based PAL. A novel complex inverse system is devised to effectively reduce the nonlinear distortion. Three practical aspects are addressed. First, the computational complexity of the Volterra filter is reduced by the parallel cascade structure with almost no compromise to the model accuracy. Second, Volterra filters are identified at discrete input levels to treat the nonlinearity that keeps changing with the time-varying audio input. Third, when the input level is high, a separation approach is proposed to refine the identified Volterra filters, which eventually improves the performance of the proposed inverse system

Compensation for nonlinear distortion of the frequency modulation based parametric array loudspeaker

The parametric array loudspeaker (PAL) modulates the audio signal on an ultrasonic carrier. When the modulated signal is transmitted in air, an audio beam is created based on the nonlinear acoustic principle. Each modulation method has advantages and disadvantages. The frequency modulation (FM) is favorable for its low cost and high volume, but the tradeoff is its complicated nonlinear distortion, which is difficult to be reduced. In this paper, the Volterra filter is adopted to model the nonlinearity of the FM-based PAL. A novel complex inverse system is devised to effectively reduce the nonlinear distortion. Three practical aspects are addressed. First, the computational complexity of the Volterra filter is reduced by the parallel cascade structure with almost no compromise to the model accuracy. Second, Volterra filters are identified at discrete input levels to treat the nonlinearity that keeps changing with the time-varying audio input. Third, when the input level is high, a separation approach is proposed to refine the identified Volterra filters, which eventually improves the performance of the proposed inverse system

A study on compensating for the distortion of the parametric array loudspeaker with changing nonlinearity

The parametric array loudspeaker (PAL) is a type of directional loudspeakers, which incurs notable distortion due to its nonlinear sound principle. Many preprocessing methods have thus been proposed to compensate for the nonlinear distortion or to linearize the PAL. In this paper, we present recent results of linearizing the PAL upon changing nonlinearity. The varying input amplitude of the PAL causes change in the amplitude of the modulated ultrasonic carrier and results in the consequent change of nonlinearity. The experiment results show that the performance of the previous linearization system is much degraded when the input amplitude is different from the sine sweep used for the Volterra filter identification. Moreover, it is also observed that when the input amplitude is very large, the identification accuracy of the Volterra filter also decreases

Linearization of the parametric array loudspeaker upon varying input amplitudes

In spite of being a compact directional sound device, the parametric array loudspeaker (PAL) has often been criticized for its severe nonlinear distortion. In some preliminary studies, the nonlinear distortion is able to be reduced by using the linearization system based on Volterra filter identification, which models the nonlinear sound process of the PAL. However, the nonlinearity of the PAL changes with the input amplitude. When the input amplitude is high enough, there is strong high-order nonlinearity and the 2nd-order Volterra kernel cannot be accurately identified. Therefore, an improved identification method of the 2nd-order Volterra kernel is proposed to exclude the interference from the 4th-order nonlinearity

A linearization system for parametric array loudspeakers using the parallel cascade Volterra filter

The parametric array loudspeaker (PAL) is well known for its ability to radiate a narrow sound beam from a relatively small ultrasonic emitter. Nonlinear distortions commonly occur in the self-demodulated sound of the PAL. Based on the Volterra filter modeling the self-demodulation process of the PAL, a linearization system can be developed for the PAL. However, the computational complexity of the Volterra filter increases dramatically with the tap length. In this paper, the parallel cascade structure is adopted to implement the Volterra filter. The experiment results demonstrate that the computational complexity of the Volterra filter is significantly reduced by using the parallel cascade structure, and based on such an implementation of the Volterra filter, the performance of the linearization system is not compromised