Semiconductors & ICs

Radiation-Insensitive Inverse Majority Gates

These gates would be implemented as microscopic vacuum electronic devices.

To help satisfy a need for high-density logic circuits insensitive to radiation, it has been proposed to realize inverse majority gates as microscopic vacuum electronic devices. In comparison with solid-state electronic devices ordinarily used in logic circuits, vacuum electronic devices are inherently much less adversely affected by radiation and extreme temperatures.

Posted in: Briefs, TSP, Semiconductors & ICs, Integrated circuits, Radiation protection

Performance of 1mm² Silicon Photomultipliers

A silicon photomultiplier (SPM) is a new type of semiconductor detector that has the potential to replace the photo- multiplier tube (PMT) detector in many applications. In common with a PMT detector, the output of an SPM is an easily detectable current pulse for each detected photon and can be used in both photon counting mode and as an analogue (photocurrent) detector. However, the SPM also has a distinct advantage over PMT detectors. The photon-induced current pulse from a PMT varies greatly from photon to photon, due to the statistics of the PMT multiplication process (excess noise). In contrast, the current pulse from an SPM is identical from photon to photon. This gives the SPM a distinct advantage in photon counting applications as it allows the associated electronics to be greatly simplified. Identical pulses also mean that the SPM can resolve the number of photons in weak optical pulses, so-called photon number resolution. This is critical in a number of applications including linear-optics quantum computing.

Posted in: Articles, Semiconductors & ICs, Detectors, Semiconductors, Test equipment and instrumentation

Dual-Input AND Gate From Single-Channel Thin-Film FET

These transistors show potential as large-area, low-cost electronic circuitry on rigid and flexible substrates.

A regio-regular poly (3-hexylthiophene) (RRP3HT) thin-film transistor having a split-gate architecture has been fabricated on a doped silicon/silicon nitride substrate and characterized. RRP3HT is a semiconducting polymer that has a carrier mobility and on/off ratio when used in a field effect transistor (FET) configuration. This commercially available polymer is very soluble in common organic solvents and is easily processed to form uniform thin films. The most important polymer-based device fabricated and studied is the FET, since it forms the building block in logic circuits and switches for active matrix (light-emitting-diode) (LED) displays, smart cards, and radio frequency identification (RFID) cards.

Posted in: Briefs, TSP, Semiconductors & ICs, Architecture, Transistors, Product development, Fabrication, Polymers, Semiconductors

Split-Block Waveguide Polarization Twist for 220 to 325 GHz

This device is superior to conventional twisted rectangular waveguides for submillimeter wavelengths.

Figure 1. A Channel Having Asymmetric Steps is cut into the lower block.An identical channel is cut into the upper block. Then with the help ofalignment pins, the blocks are assembled so that the two channels mergeinto one channel that makes a transition between two orthogonal orientationsof a WR-3 waveguide.A split-block waveguide circuit that rotates polarization by 90° has been designed with WR-3 input and output waveguides, which are rectangular waveguides used for a nominal frequency range of 220 to 325 GHz. Heretofore, twisted rectangular waveguides equipped with flanges at the input and output have been the standard means of rotating the polarizations of guided microwave signals. However, the fabrication and assembly of such components become difficult at high frequency due to decreasing wavelength, such that twisted rectangular waveguides become impractical at frequencies above a few hundred gigahertz. Conventional twisted rectangular waveguides are also not amenable to integration into highly miniaturized subassemblies of advanced millimeter- and submillimeter- wave detector arrays now undergoing development. In contrast, the present polarization-rotating waveguide can readily be incorporated into complex integrated waveguide circuits such as miniaturized detector arrays fabricated by either conventional end milling of metal blocks or by deep reactive ion etching of silicon blocks. Moreover, the present splitblock design can be scaled up in frequency to at least 5 THz.

Posted in: Briefs, TSP, Semiconductors & ICs, Waveguides

Error-Detecting Counters for FPGA and ASIC State Machines

Inconsistencies between main and auxiliary counts would be detected.

Error-detecting counters have been proposed as parts of fault-tolerant finite state machines that could be implemented in field-programmable gate arrays (FPGAs) and application-specific integrated circuits that perform sequential logic functions. The use of error-detecting counters would complement the fault-tolerant coding schemes described in “Fault-Tolerant Coding for State Machines” (NPO-41050), in this issue on page 55. Counters are often used in state machines in cases in which it is necessary to represent large numbers of states and/or to count clock cycles between certain states. To ensure reliability, it is necessary to ensure that the counters are as free of faults as are the other parts of the state machines.

Posted in: Briefs, TSP, Semiconductors & ICs, Finite element analysis, Integrated circuits, On-board diagnostics, On-board diagnostics (OBD), Semiconductors, Reliability

Efficient G⁴FET-Based Logic Circuits

Fewer G4FETs than conventional transistors would be needed to implement logic functions.

A total of 81 optimal logic circuits based on four-gate field-effect transistors (G4FETs) have been designed to implement all Boolean functions of up to three variables. The purpose of this development was to lend credence to the expectation that logic circuits based on G4FETs could be more efficient (in the sense that they could contain fewer transistors), relative to functionally equivalent logic circuits based on conventional transistors.

Posted in: Briefs, TSP, Semiconductors & ICs, Mathematical models, Integrated circuits, Semiconductors

Circuit and Method for Communication Over DC Power Line

New technique usable in harsh, high-heat environments, allows for networking and smart vehicle operation with no additional wiring beyond power.

A circuit and method for transmitting and receiving on-off-keyed (OOK) signals with fractional signal-to-noise ratios uses available high-temperature silicon-on-insulator (SOI) components to move computational, sensing, and actuation abilities closer to high- temperature or high- ionizing radiation environments such as vehicle engine compartments, deep-hole drilling environments, industrial control and monitoring of processes like smelting, and operations near nuclear reactors and in space. This device allows for the networking of multiple, like nodes to each other and to a central processor. It can do this with nothing more than the already in-situ power wiring of the system. The device’s microprocessor allows it to make intelligent decisions within the vehicle operational loop and to effect control outputs to its associated actuators. The figure illustrates how each node converts digital serial data to OOK 18-kHz in transmit mode and vice-versa in receive mode; though operations at lower frequencies or up to a megahertz are within reason using this method and these parts.

Posted in: Briefs, TSP, Semiconductors & ICs, Data acquisition and handling

Advanced Ultra-Thin Integrated Electronics on Membranes

Flexible integrated circuits are integrated with other circuitry on flexible membranes.

A method of fabricating flexible assemblies comprising flexible integrated circuits bonded onto or into flexible membranes has been developed. The method provides for bonding of thinned (more specifically, thin enough to be flexible) integrated-circuit chips to the membranes and for electrical connection of the integrated circuits to other circuitry on or in the membranes. The method is expected to enable the further development of a variety of membrane-based flexible, lightweight electronic systems and assemblies — for example, phasedarray antenna assemblies comprising integrated-circuit transmitting/ receiving (T/R) modules further integrated with arrays of transmission lines and antenna radiator elements.

Posted in: Briefs, Semiconductors & ICs, Electronic equipment, Integrated circuits, Fabrication

MMIC Amplifiers for 90 to 130 GHz

Output power exceeds that of prior solid-state amplifiers operating above 110 GHz.

The figure shows two monolithic microwave integrated-circuit (MMIC) amplifier chips optimized to function in the frequency range of 90 to 130 GHz, covering nearly all of F-band (90 – 140 GHz). These amplifiers were designed specifically for local-oscillator units in astronomical radio telescopes such as the Atacama Large Millimeter Array (ALMA). They could also be readily adapted for use in electronic test equipment, automotive radar systems, and communications systems that operate between 90 and 130 GHz.

Posted in: Briefs, TSP, Semiconductors & ICs, Amplifiers

Microrectenna: A Terahertz Antenna and Rectifier on a Chip

Microscopic rectennas would supply DC power to microdevices.

A microrectenna that would operate at a frequency of 2.5 THz has been designed and partially fabricated. The circuit is intended to be a prototype of an extremely compact device that could be used to convert radio-beamed power to DC to drive microdevices (see Figure 1).

Posted in: Briefs, Semiconductors & ICs, Antennas, Integrated circuits

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