Semiconductors & ICs

InP Heterojunction Bipolar Transistor Amplifiers to 255 GHz

These amplifiers can be used in millimeter-wave imaging systems for weapons detection and airport security, and for radar instruments.

Two single-stage InP heterojunction bipolar transistor (HBT) amplifiers operate at 184 and 255 GHz, using Northrop Grumman Corporation’s InP HBT MMIC (monolithic microwave integrated circuit) technology. At the time of this reporting, these are reported to be the highest HBT amplifiers ever created. The purpose of the amplifier design is to evaluate the technology capability for high-frequency designs and verify the model for future development work.

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

Submillimeter-Wave Amplifier Module With Integrated Waveguide Transitions

This technique can be used in submillimeter-wave imaging in homeland security, weapons detection, and commercial test equipment.

To increase the usefulness of monolithic millimeter-wave integrated circuit (MMIC) components at submillimeter-wave frequencies, a chip has been designed that incorporates two integrated, radial E-plane probes with an MMIC amplifier in between, thus creating a fully integrated waveguide module. The integrated amplifier chip has been fabricated in 35-nm gate length InP high-electron-mobility-transistor (HEMT) technology. The radial probes were mated to grounded coplanar waveguide input and output lines in the internal amplifier. The total length of the internal HEMT amplifier is 550 μm, while the total integrated chip length is 1,085 μm. The chip thickness is 50 μm with the chip width being 320 μm.

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

Economical Implementation of a Filter Engine in an FPGA

There are numerous potential uses in general signal processing.

A logic design has been conceived for a field-programmable gate array (FPGA) that would implement a complex system of multiple digital state-space filters. The main innovative aspect of this design lies in providing for reuse of parts of the FPGA hardware to perform different parts of the filter computations at different times, in such a manner as to enable the timely performance of all required computations in the face of limitations on available FPGA hardware resources.

Posted in: Briefs, TSP, Semiconductors & ICs, Architecture, Integrated circuits, Architecture, Integrated circuits, Performance tests

Logic Gates Made of N-Channel JFETs and Epitaxial Resistors

Gates could be implemented in SiC ICs for operation at high temperatures.

Prototype logic gates made of n-channel junction field-effect transistors (JFETs) and epitaxial resistors have been demonstrated, with a view toward eventual implementation of digital logic devices and systems in silicon carbide (SiC) integrated circuits (ICs). This development is intended to exploit the inherent ability of SiC electronic devices to function at temperatures from 300 to somewhat above 500 °C and withstand large doses of ionizing radiation. SiC-based digital logic devices and systems could enable operation of sensors and robots in nuclear reactors, in jet engines, near hydrothermal vents, and in other environments that are so hot or radioactive as to cause conventional silicon electronic devices to fail.

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

Vertical Isolation for Photodiodes in CMOS Imagers

Diffusion cross-talk would be reduced substantially.

In a proposed improvement in complementary metal oxide/semi con ductor (CMOS) image detectors, two additional implants in each pixel would effect vertical isolation between the metal oxide/ semiconductor field-effect transistors (MOSFETs) and the photodiode of the pixel. This improvement is expected to enable separate optimization of the designs of the photodiode and the MOSFETs so as to optimize their performances independently of each other. The purpose to be served by enabling this separate optimization is to eliminate or vastly reduce diffusion cross-talk, thereby increasing sensitivity, effective spatial resolution, and color fidelity while reducing noise.

Posted in: Briefs, Semiconductors & ICs, Imaging, Imaging and visualization, Imaging, Imaging and visualization

Onboard Data Processor for Change-Detection Radar Imaging

This system could be used to map earthquakes, landslides, floods, and wildfires.

A computer system denoted a change-detection onboard processor (CDOP) is being developed as a means of processing the digitized output of a synthetic-aperture radar (SAR) apparatus aboard an aircraft or spacecraft to generate images showing changes that have occurred in the terrain below between repeat passes of the aircraft or spacecraft over the terrain. When fully developed, the CDOP is intended to be capable of generating SAR images and/or SAR differential interferograms in nearly real time. The CDOP is expected to be especially useful for understanding some large-scale natural phenomena and/or mitigating natural hazards: For example, it could be used for near-real-time observation of surface changes caused by floods, landslides, forest fires, volcanic eruptions, earthquakes, glaciers, and sea ice movements. It could also be used to observe such longer-term surface changes as those associated with growth of vegetation (relevant to estimation of wildfire fuel loads).

Posted in: Briefs, TSP, Semiconductors & ICs, Computer software / hardware, Computer software and hardware, Imaging, Imaging and visualization, Radar, Computer software / hardware, Computer software and hardware, Imaging, Imaging and visualization, Radar, Terrain, Weather and climate

HEMT Amplifiers and Equipment for Their On-Wafer Testing

Power levels in CPW circuits can be measured without packaging.

Power amplifiers comprising InP-based high-electron-mobility transistors (HEMTs) in coplanar-waveguide (CPW) circuits designed for operation at frequencies of hundreds of gigahertz, and a test set for on-wafer measurement of their power levels have been developed. These amplifiers utilize an advanced 35-nm HEMT monolithic microwave integrated-circuit (MMIC) technology and have potential utility as local- oscillator drivers and power sources in future submillimeter-wavelength heterodyne receivers and imaging systems. The test set can reduce development time by enabling rapid output power characterization, not only of these and similar amplifiers, but also of other coplanar-waveguide power circuits, without the necessity of packaging the circuits.

Posted in: Briefs, Semiconductors & ICs, Amplifiers, Integrated circuits, Amplifiers, Integrated circuits, Test procedures

On-Wafer Measurement of a Silicon-Based CMOS VCO at 324 GHz

Compact, low-power, electronically tunable submillimeter-wave local oscillators are now feasible.

The world’s first silicon- based complementary metal oxide/semi- conductor (CMOS) integrated-circuit voltage-controlled oscillator (VCO) operating in a frequency range around 324 GHz has been built and tested. Concomitantly, equipment for measuring the performance of this oscillator has been built and tested. These accomplishments are intermediate steps in a continuing effort to develop low-power- consumption, low-phase-noise, electronically tunable signal generators as local oscillators for heterodyne receivers in submillimeter-wavelength (frequency > 300 GHz) scientific instruments and imaging systems. Submillimeter-wavelength imaging systems are of special interest for military and law-enforcement use because they could, potentially, be used to detect weapons hidden behind clothing and other opaque dielectric materials. In comparison with prior submillimeter-wavelength signal generators, CMOS VCOs offer significant potential advantages, including great reductions in power consumption, mass, size, and complexity. In addition, there is potential for on-chip integration of CMOS VCOs with other CMOS integrated circuitry, including phase-lock loops, analog-to-digital converters, and advanced microprocessors.

Posted in: Briefs, TSP, Semiconductors & ICs, Amplifiers, Imaging, Imaging and visualization, Integrated circuits, Semiconductor devices, Amplifiers, Imaging, Imaging and visualization, Integrated circuits, Semiconductor devices, Silicon alloys

Lower-Dark-Current, Higher-Blue-Response CMOS Imagers

Semiconductor junctions are relocated away from Si/SiO2 interfaces.

Several improved designs for complementary metal oxide/semiconductor (CMOS) integrated- circuit image detectors have been developed, primarily to reduce dark currents (leakage currents) and secondarily to increase responses to blue light and increase signal- handling capacities, relative to those of prior CMOS imagers. The main conclusion that can be drawn from a study of the causes of dark currents in prior CMOS imagers is that dark currents could be reduced by relocating p/n junctions away from Si/SiO2 interfaces. In addition to reflecting this conclusion, the improved designs include several other features to counteract dark-current mechanisms and enhance performance.

Posted in: Briefs, Semiconductors & ICs, Imaging, Imaging and visualization, Integrated circuits, Semiconductor devices, Imaging, Imaging and visualization, Integrated circuits, Semiconductor devices, Performance upgrades

Low-Temperature Supercapacitors

Electrolyte compositions are designed to extend the low-temperature operational limit.

An effort to extend the low-temperature operational limit of supercapacitors is currently underway. At present, commercially available non-aqueous supercapacitors are rated for a minimum operating temperature of –40 °C. A capability to operate at lower temperatures would be desirable for delivering power to systems that must operate in outer space or in the Polar Regions on Earth.

Posted in: Briefs, TSP, Semiconductors & ICs, Ultracapacitors and supercapacitors, Ultracapacitors and supercapacitors, Performance upgrades

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