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This paper describes a new single-input multiple-output (SIMO) mixed-mode universal biquad $G_m$–$C$ filter. It can realize all kinds of filter responses including high-pass, band-pass, low-pass, band-stop and all-pass filters, simultaneously. Moreover, in this structure, all of these filters in all states of voltage mode, current mode, transresistance mode and transconductance mode are achieved by the same topology without any convertor. The proposed filter employs three operational transconductance amplifiers (OTAs) with four inputs and one output, three fully differential OTAs and two grounded capacitors. In other words, this filter is composed of six $G_m$ blocks and two grounded capacitors. The grounded capacitors are suitable for integrated circuit implementation. In order to reduce the power consumption, the OTAs are biased in subthreshold region. In addition, sensitivity analysis is included to show the low active and passive sensitivity performances of the filter. This filter is designed and simulated in HSPICE with 0.18$\mu$m model CMOS technology parameters. The simulation results show that the filter consumes only 75$\mu$W and operates at 1.5MHz with $\pm$0.5V supply voltages and capacitors $C_1=C_2=2$pF.

Carbon fiber-reinforced polymer (CFRP) composite laminates have the characteristics of orthogonal anisotropy and heterogeneity, so the failure mechanism under low-energy impact is very complex. As a supplement to the experiment, it is necessary to develop numerical tools to predict the mechanical behavior of composite laminates under low-energy impact. In this paper, the mechanical behavior analysis framework of composite laminates under low-energy impact load is established by using the micromechanics of failure (MMF) theory and the mixed mode exponential cohesive zone model (CZM). The failure modes of intralaminar components in composite laminates are determined by MMF theory. The damage onset and evolution process of interlaminar delamination is described by the mixed mode exponential CZM. The finite element model of composite laminates under low-energy impact is developed using the Python scripts on ABAQUS/Explicit platform. The user-defined material subroutine VUMAT is written in Fortran language. The impact responses of composite laminates with several impact energies are predicted. The intralaminar failure modes and interlaminar delamination behavior are discussed in detail. The results show that the tensile failure of matrix and interlaminar shear delamination failure are the main failure modes of composite laminates under low-energy impact load. The experimental results present better consistency with the numerical analysis, indicating that the constructed multiscale analysis method is efficient and accurate. This study expands the analysis method of mechanical behavior of composite laminates under low-energy impact. The constructed mixed mode exponential CZM also has guiding significance for the failure analysis of other bonding materials.