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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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This paper focuses on analog/digital electronics at low-temperatures. The experiments cover separate tests of the whole Evolvable Hardware system: the Evolutionary Processor (the DSP in the SABLE system), Xilinx Virtes II Pro FPGA evaluation board, and the Reconfigurable analog array components tested at low and high temperatures.
Monostable circuit design satisfies space requirements for minimum power dissipation
Screening methods for metal oxide semiconductor field effect transistors and resistors, impact survival testing of spacecraft electronic parts, and parachute jettisoning from planetary capsules
Fully-depleted silicon on insulator transitors were characterized at low temperatures for performance reliability.
For use in cryogenic applications such as bolometer and x-ray microcalorimeter arrays, pre-amplifying Junction Field Effect Transistors (JFETs) are often required for the readout electronics. The optimum operating temperature of the JFETs is 130 Kelvin while the cryogenic detectors operate in the milli-Kelvin range. Thus, the JFETs must be heated up but thermally isolated from the surrounding cryogenic instruments. In the past, the thermal isolation was accomplished by suspending the JFETs with low conductance wires such as manganium or stainless steel on a Kevlar support platform [I]. This also achieved electrical connections. However, this assembly required manual soldering work, which could raise a reliability issue for the cryogenic applications. In order to eliminate the manual work, polyimide micro-wires were developed [2]. The wires must be of sufficient length to decrease the heat load and in tension to prevent microphonic noise from vibration of the wires: the polyimide wires were patterned into llS"shaped curves over a thin metal wires such as aluminum, titanium, or niobium. The bilayer of the films were then suspended by etching silicon substrate thus to make freestanding air bridges (enough explanation?). In this paper, we present a method to fabricate micromachined JFET mechanical modules suspended by polyimide Pyraline micro-wires and heated up with built-in aluminum micro-heaters.
This paper presents research results dealing with power MOSFETs (metal oxide semiconductor field effect transistor) within the prognostics and health management of electronics. Experimental results are presented for the identification of the on-resistance as a precursor to failure of devices with die-attach degradation as a failure mechanism. Devices are aged under power cycling in order to trigger die-attach damage. In situ measurements of key electrical and thermal parameters are collected throughout the aging process and further used for analysis and computation of the on-resistance parameter. Experimental results show that the devices experience die-attach damage and that the on-resistance captures the degradation process in such a way that it could be used for the development of prognostics algorithms (data-driven or physics-based).
The progress of Jet Propulsion Laboratory in developing gallium arsenide junction field-effect transistors (GaAs JFETs) for application in infrared readout electronics operating below 10 Kelvin is discussed.
Power field-effect transistors reduce energy waste and simplify interconnections. Current switch containing power field-effect transistor (PFET) placed in series with each load in fault-tolerant power-distribution system. If system includes several loads and supplies, switches placed in series with adjacent loads and supplies. System of switches protects against overloads and losses of individual power sources.
Procedures for cleaning, decontamination, and encapulation of electronic circuits containing metal-oxide silicon field effect transistors
A search of literature concerning the long term effects of nuclear radiation on electronic parts was conducted to determine the effects of radiation fields encountered on deep space missions to parts used in the Pioneer Spacecraft. Topics discussed include: the various types of radiation the spacecraft will encounter, effects of radiation on electronic parts, and estimates of the damage thresholds for transistors and integrated circuits used on the Pioneer Spacecraft.
The design verification tests which were conducted on the electromechanical actuator are described. A description is also given of the power components tests which were conducted to aid in selecting the power transistors for use in the single-channel power electronics breadboard and the results of tests which were conducted on the power electronics breadboard.
In an effort to investigate metal surface corrosion and the breakdown of metal protective coatings the AC Impedance Method was applied to zinc chromate primer coated 2219-T87 aluminum. The model 368-1 AC Impedance Measurement System recently acquired by the MSFC Corrosion Research Branch was used to monitor changing properties of coated aluminum disks immersed in 3.5% NaCl buffered at ph 5.5 over three to four weeks. The DC polarization resistance runs were performed on the same samples. The corrosion system can be represented by an electronic analog called an equivalent circuit that consists of transistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for resistances and capacities that can be assigned in the equivalent circuit following a least squares analysis of the data describe changes that occur on the corroding metal surface and in the protective coating. A suitable equivalent circuit was determined that predicts the correct Bode phase and magnitude for the experimental sample. The DC corrosion current density data are related to equivalent circuit element parameters.
A method for evolving a circuit comprising configuring a plurality of transistors using a plurality of reconfigurable switches so that each of the plurality of transistors has a terminal coupled to a terminal of another of the plurality of transistors that is controllable by a single reconfigurable switch. The plurality of reconfigurable switches being controlled in response to a chromosome pattern. The plurality of reconfigurable switches may be controlled using an annealing function. As such, the plurality of reconfigurable switches may be controlled by selecting qualitative values for the plurality of reconfigurable switches in response to the chromosomal pattern, selecting initial quantitative values for the selected qualitative values, and morphing the initial quantitative values. Typically, subsequent quantitative values will be selected more divergent than the initial quantitative values. The morphing process may continue to partially or to completely polarize the quantitative values.
The High Temperature Integrated Electronics and Sensors (HTIES) Program at the NASA Lewis Research Center is currently developing silicon carbide (SiC) for use in harsh conditions where silicon, the semiconductor used in nearly all of today's electronics, cannot function. The HTIES team recently fabricated and demonstrated the first semiconductor digital logic gates ever to function at 600 C.
Porous-floating-gate, "vertical" field-effect transistor proposed as programmable analog memory device especially suitable for use in electronic neural networks. Analog value of electrical conductance of device represents synaptic weight (strength of synaptic connection) repeatedly modified by application of suitable writing or erasing voltage. Suited for hardware implementations of massively parallel neural-network architectures for two important reasons: vertical transistor structure requires only two external electrodes, and use of tailored amorphous semiconductors provides choice of very wide range of low conductivity values, dictated by overall power dissipation requirements in massively parallel neural-network circuits.
Very high performance is being developed in compound semiconductor transistors. High frequency and low noise figure operation in the GaAs FET have already been established. Substantially more performance increases are expected. A comparison of compound semiconductor materials, and their alloys, the physical concepts of high average electron velocity, and the special benefits of modulation doped heterojunction FET devices is presented.
Limiting circuit protects the main power supply of electronic modules and limits the current drawn by each module should a short circuit occur. It limits current within one mA when used with direct current of either polarity, or with pulse or ac power sources from direct current to 100 kHz.
An evolvable circuit includes a plurality of reconfigurable switches, a plurality of transistors within a region of the circuit, the plurality of transistors having terminals, the plurality of transistors being coupled between a power source terminal and a power sink terminal so as to be capable of admitting power between the power source terminal and the power sink terminal, the plurality of transistors being coupled so that every transistor to transistor terminal coupling within the region of the circuit comprises a reconfigurable switch.