Semiconductors & ICs

Waveguide Transition for Submillimeter-Wave MMICs

An integrated waveguide-to-MMIC (monolithic microwave integrated circuit) chip operating in the 300-GHz range is designed to operate well on highpermittivity semiconductor substrates typical for an MMIC amplifier, and allows a wider MMIC substrate to be used, enabling integration with larger MMICs (power amplifiers). The waveguide-to- CBCPW (conductor-backed coplanar waveguide) transition topology is based on an integrated dipole placed in the Eplane of the waveguide module. It demonstrates low loss and good impedance matching. Measurement and simulation demonstrate that the loss of the transition and waveguide loss is less than 1-dB over a 340-to-380-GHz bandwidth.

Posted in: Briefs, TSP, Semiconductors & ICs, Radar, Waveguides, Semiconductors, Performance tests

Hardware Implementation of a Bilateral Subtraction Filter

Modules like this one are necessary for real-time stereoscopic machine vision.

A bilateral subtraction filter has been implemented as a hardware module in the form of a field-programmable gate array (FPGA). In general, a bilateral subtraction filter is a key subsystem of a high-quality stereoscopic machine vision system that utilizes images that are large and/or dense. Bilateral subtraction filters have been implemented in software on general-purpose computers, but the processing speeds attainable in this way — even on computers containing the fastest processors — are insufficient for real-time applications. The present FPGA bilateral subtraction filter is intended to accelerate processing to real-time speed and to be a prototype of a link in a stereoscopic-machine-vision processing chain, now under development, that would process large and/or dense images in real time and would be implemented in an FPGA.

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

Lattice-Matched Semiconductor Layers on Single Crystalline Sapphire Substrate

Rhombohedrally grown lattice-matched semiconductor alloys can be used in photovoltaic solar cells and photon detectors.

SiGe is an important semiconductor alloy for high-speed field effect transistors (FETs), high-temperature thermoelectric devices, photovoltaic solar cells, and photon detectors. The growth of SiGe layer is difficult because SiGe alloys have different lattice constants from those of the common Si wafers, which leads to a high density of defects, including dislocations, micro-twins, cracks, and delaminations.

Posted in: Briefs, TSP, Semiconductors & ICs, Finite element analysis, Fabrication, Alloys, Semiconductors

Low-Noise MMIC Amplifiers for 120 to 180 GHz

Potential applications include radar, communications, radiometry, and millimeter-wave imaging.

Three-stage monolithic millimeter-wave integrated-circuit (MMIC) amplifiers capable of providing useful amounts of gain over the frequency range from 120 to 180 GHz have been developed as prototype low-noise amplifiers (LNAs) to be incorporated into instruments for sensing cosmic microwave background radiation. There are also potential uses for such LNAs in electronic test equipment, passive millimeter-wave imaging systems, radar receivers, communication receivers, and systems for detecting hidden weapons. The main advantage afforded by these MMIC LNAs, relative to prior MMIC LNAs, is that their coverage of the 120-to-180-GHz frequency band makes them suitable for reuse in a wider variety of applications without need to redesign them. Each of these MMIC amplifiers includes InP transistors and coplanar waveguide circuitry on a 50-μm-thick chip (see Figure 1). Coplanar waveguide transmission lines are used for both applying DC bias and matching of input and output impedances of each transistor stage. Via holes are incorporated between top and bottom ground planes to suppress propagation of electromagnetic modes in the substrate.

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

Three MMIC Amplifiers for the 120-to-200 GHz Frequency Band

These would complement previously reported MMIC amplifiers designed for overlapping frequency bands.

Closely following the development reported in the article, "Low-Noise MMIC Amplifiers for 120 to 180 GHz" (NPO-42783), three new monolithic microwave integrated circuit (MMIC) amplifiers that would operate in the 120-to-200- GHz frequency band have been designed and are under construction at this writing. The active devices in these amplifiers are InP high-electron-mobility transistors (HEMTs). These amplifiers (see figure) are denoted the LSLNA150, the LSA200, and the LSA185, respectively.

Posted in: Briefs, TSP, Semiconductors & ICs, Amplifiers, Integrated circuits, Transistors

Parallel-Processing CMOS Circuitry for M-QAM and 8PSK TCM

There has been some additional development of parts reported in “Multi-Modulator for Bandwidth-Efficient Communication” (NPO-40807), NASA Tech Briefs, Vol. 32, No. 6 (June 2009), page 34. The focus was on

Posted in: Briefs, Semiconductors & ICs, Architecture, Integrated circuits, Semiconductors, Parts

Circuit for Driving Piezoelectric Transducers

Circuits similar to this one could be useful in ultrasonic cleaners.

The figure schematically depicts an oscillator circuit for driving a piezoelectric transducer to excite vibrations in a mechanical structure. The circuit was designed and built to satisfy application-specific requirements to drive a selected one of 16 such transducers at a regulated amplitude and frequency chosen to optimize the amount of work performed by the transducer and to compensate for both (1) temporal variations of the resonance frequency and damping time of each transducer and (2) initially unknown differences among the resonance frequencies and damping times of different transducers. In other words, the circuit is designed to adjust itself to optimize the performance of whichever transducer is selected at any given time. The basic design concept may be adaptable to other applications that involve the use of piezoelectric transducers in ultrasonic cleaners and other apparatuses in which high-frequency mechanical drives are utilized.

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

Board Saver for Use With Developmental FPGAs

A printed-circuit board is protected against repeated soldering and unsoldering.

A device denoted a board saver has been developed as a means of reducing wear and tear of a printed-circuit board onto which an antifuse field-programmable gate array (FPGA) is to be eventually soldered permanently after a number of design iterations. The need for the board saver or a similar device arises because (1) antifuse- FPGA design iterations are common and (2) repeated soldering and unsoldering of FPGAs on the printed-circuit board to accommodate design iterations can wear out the printed-circuit board. The board saver is basically a solderable/unsolderable FPGA receptacle that is installed temporarily on the printed-circuit board.

Posted in: Briefs, Semiconductors & ICs, Integrated circuits, Protective structures

Digital Synchronizer Without Metastability

A proposed design for a digital synchronizing circuit would eliminate metastability that plagues flip-flop circuits in digital input/output interfaces. This metastability is associated with sampling, by use of flip-flops, of an external signal that is asynchronous with a clock signal that drives the flip-flops: it is a temporary flip-flop failure that can occur when a rising or falling edge of an asynchronous signal occurs during the setup and/or hold time of a flip-flop.

Posted in: Briefs, Semiconductors & ICs

Efficient Multiplexer FPGA Block Structures Based on G⁴FETs

Fewer G4FETs than conventional transistors would be needed to implement multiplexers.

Generic structures have been conceived for multiplexer blocks to be implemented in field-programmable gate arrays (FPGAs) based on four-gate field-effect transistors (G4FETs). This concept is a contribution to the continuing development of digital logic circuits based on G4FETs and serves as a further demonstration 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

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