Total ionizing dose effect modeling method for CMOS digital-integrated circuit

Simulating the total ionizing dose(TID)of an electrical system using transistor-level models can be difficult and expensive,particularly for digital-integrated circuits(ICs).In this study,a method for modeling TID effects in complementary metaloxide semiconductor(CMOS)digital ICs based on the input/output buffer information specification(IBIS)was proposed.The digital IC was first divided into three parts based on its internal structure:the input buffer,output buffer,and functional area.Each of these three parts was separately modeled.Using the IBIS model,the transistor V-I characteristic curves of the buffers were processed,and the physical parameters were extracted and modeled using VHDL-AMS.In the functional area,logic functions were modeled in VHDL according to the data sheet.A golden digital IC model was developed by combining the input buffer,output buffer,and functional area models.Furthermore,the golden ratio was reconstructed based on TID experimental data,enabling the assessment of TID effects on the threshold voltage,carrier mobility,and time series of the digital IC.TID experiments were conducted using a CMOS non-inverting multiplexer,NC7SZ157,and the results were compared with the simulation results,which showed that the relative errors were less than 2%at each dose point.This confirms the practicality and accuracy of the proposed modeling method.The TID effect model for digital ICs developed using this modeling technique includes both the logical function of the IC and changes in electrical properties and functional degradation impacted by TID,which has potential applications in the design of radiation-hardening tolerance in digital ICs.

Modeling operation amplifier based on VHDL-AMS for TID effect

A model of the operational amplifier based on VHDL-AMS is proposed. According to needs of simulating the total ionizing dose(TID) radiation effect, parameters of operational amplifier are taken into account when the performance is specified. The operational amplifier model used for the TID radiation effect simulation is completed after verifying each modeled parameter. And a parameter for describing the external environment is introduced to make the model combined with TID. Finally, an example is used to illustrate the TID effect on the operational amplifier of MC14573, proving the validity of the model.

Microstructure,cracking behavior and control of Al-Fe-V-Si alloy produced by selective laser melting

Selective laser melting(SLM)technology based on atomized powder was used to fabricate Al-8.5Fe-1.3V-1.7Si(wt%)alloy parts.The microstructure and crack characterization of SLM samples fabricated at various conditions were presented.Results show that the cracks appear periodically along the building direction,initiate preferably at the outer edges of the as-built samples and propagated along the remelting border zone(RBZ)into deposited layers.Solid-phase cracking is proposed according to the fracture morphology.The thermal-induced residual stress during SLM combined with the precipitation of relatively large-sized Al_mFe phase in the RBZ results in the formation of cracks.Enhancing scanning speed and hatch distance enable to reduce the cracking sensitivity.The crack-free Al-8.5Fe-1.3V-1.7Si parts can be fabricated at optimized parameters of laser power of 320 W,scanning speed of 1000 mm·s^(-1)and hatch distance of0.10 mm along with proper laser pre-heating procedure.The samples built horizontally show good ultimate tensile properties of 454 MPa in average with the elongation of7.2%.

Selective Laser Melting of an Al–Fe–V–Si Alloy:Microstructural Evolution and Thermal Stability

Selective laser melting was used to produce an aluminum alloy Al-8.5Fe-1.3V-1.7Si（wt%）. The effects of heat treatment on microstructure evolution and phase stability during long-term thermal exposure of the deposits were investigated. Results show that the microquasi-crystalline phase, Al12（Fe,V）3Si and AlmF e metastable phases coexisted with α-Al in the as-produced alloy. Annealing at 400 ℃ resulted in decomposition of microquasi-crystalline phase and supersaturated α-Al into Al12（Fe, V）3Si phase in the fusion zone, accompanied by the decrease in alloy hardness. The activation energy of this decomposition process was 115 k J/mol. A more homogenous microstructure was obtained after annealing at 400 °C for 60 min,which was resistant to coarsening exposed at 425 °C up to 500 h. The Al12（Fe,V）3Si and AlmF e phases were coarsened at 475 and 525℃ with increasing the exposure time. Coarsening of Al12（Fe,V）3Si phase was attributed to a combination of volume diffusion and grain boundary diffusion mechanism of Fe. Heat treatment at 600℃ resulted in accelerated microstructure coarsening and formation of large-sized equilibrium phases, which signi？cantly degraded the room temperature microhardness.

Moisture sorption characteristics of freeze-dried human platelets

Freeze-drying is a promising method for a long-term storage of human platelets.The moisture sorption characteristics of freeze-dried human platelets(FDHPs) were studied in this paper.The moisture sorption isotherms of FDHPs and freeze-dried lyophilization buffer(FDLB) were measured at 4,25,and 37°C.The experimental data were fitted to Brunauer-Emmett-Teller(BET) and Guggenheim-Anderson-de Boer(GAB) equations.There were no sig-nificant statistical differences(P>0.05) between the sorption characteristics of FDHPs and FDLB at 4 and 25°C,while FDHPs absorbed more water at 37°C.The net isosteric heat of sorption was derived.The heat for FDHPs showed an abnormal negative value at low moisture contents when 25 and 37°C data were used.Dynamic sorption experiments were carried out at 25°C with environmental water activity controlled at 0.75,0.85,and 0.90.The moisture diffusion coefficient was fitted to be 8.24×10 -12 m 2 /s when experimental data at initial time were used.These results would be helpful in choosing prehydration and storage condition for FDHPs.