Semiconductors & ICs

Single-Chip T/R Module for 1.2 GHz

T/R modules can be made smaller and at lower cost. A single-chip CMOS-based (complementary- metal-oxide-semi- conductor- based) transmit/receive (T/R) module is being developed for L-band radar systems. Previous T/R module implementations required multiple chips employing different technologies (GaAs, Si, and others) combined with off-chip transmission lines and discrete components including circulators. The new design eliminates the bulky circulator, significantly reducing the size and mass of the T/R module. Compared to multi-chip designs, the single- chip CMOS can be implemented with lower cost. These innovations enable cost-effective realization of advanced phased array and synthetic aperture radar systems that require integration of thousands of T/R modules.

Posted in: Semiconductors & ICs, Briefs, TSP

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Waveguide Power-Amplifier Module for 80 to 150 GHz

The amplifier can now be connected to other equipment more easily. A waveguide power-amplifier module capable of operating over the frequency range from 80 to 150 GHz has been constructed. The module comprises a previously reported power amplifier packaged in a waveguide housing that is compatible with WR-8 waveguides. (WR-8 is a standard waveguide size for the nominal frequency range from 90 to 140 GHz.) Because the amplifier in its unpackaged form was a single, fragile InP chip, it was necessary to use special probes to make electrical connections between the amplifier and test equipment in order to measure the power gain and other aspects of amplifier performance. In contrast, the waveguide poweramplifier module is robust and can be bolted to test equipment and to other electronic circuits with which the amplifier must be connected for normal operation. The amplifier in its unpackaged form was reported in “Power Amplifier With 9 to 13 dB of Gain from 65 to 146 GHz” (NPO-20880), NASA Tech Briefs, Vol. 25, No. 1 (January 2001), page 44.

Posted in: Semiconductors & ICs, Briefs, TSP

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Analog Nonvolatile Computer Memory Circuits

Digital data would be stored in analog form in FFETs. In nonvolatile random-access memory (RAM) circuits of a proposed type, digital data would be stored in analog form in ferroelectric field-effect transistors (FFETs). This type of memory circuit would offer advantages over prior volatile and nonvolatile types: In a conventional complementary metal oxide/semiconductor static RAM, six transistors must be used to store one bit, and storage is volatile in that data are lost when power is turned off. In a conventional dynamic RAM, three transistors must be used to store one bit, and the stored bit must be refreshed every few milliseconds. In contrast, in a RAM according to the proposal, data would be retained when power was turned off, each memory cell would contain only two FFETs, and the cell could store multiple bits (the exact number of bits depending on the specific design).

Posted in: Semiconductors & ICs, Briefs, TSP

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Circuit for Full Charging of Series Lithium-Ion Cells

Differences among cells would no longer prevent full charging. An advanced charger has been proposed for a battery that comprises several lithium-ion cells in series. The proposal is directed toward charging the cells in as nearly an optimum manner as possible despite unit-to-unit differences among the nominally identical cells.

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Imaging Spectrometer on a Chip

One integrated circuit would perform the functions of a conventional several-kilogram spectrometer. A proposed visible-light imaging spectrometer on a chip would be based on the concept of a heterostructure comprising multiple layers of silicon-based photodetectors interspersed with long-wavelength-pass optical filters. In a typical application, this heterostructure would be replicated in each pixel of an image-detecting integrated circuit of the active-pixel-sensor type (see figure).

Posted in: Semiconductors & ICs, Briefs, TSP

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Four-Quadrant Analog Multipliers Using G4-FETs

Devices with independently biased multiple inputs are exploited to simplify multiplier circuits. Theoretical analysis and some experiments have shown that the silicon-on-insulator (SOI) 4-gate transistors known as G4-FETs can be used as building blocks of four-quadrant analog voltage multiplier circuits. Whereas a typical prior analog voltage multiplier contains between six and 10 transistors, it is possible to construct a superior voltage multiplier using only four G4-FETs.

Posted in: Semiconductors & ICs, Briefs, TSP

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SiC Multi-Chip Power Modules as Power-System Building Blocks

Fault-tolerant power-supply systems could be constructed and expanded relatively inexpensively. The term “SiC MCPMs” (wherein “MCPM” signifies “multi-chip power module”) denotes electronic power-supply modules containing multiple silicon carbide power devices and silicon-on-insulator (SOI) control integrated-circuit chips. SiC MCPMs are being developed as building blocks of advanced expandable, reconfigurable, fault-tolerant power-supply systems. Exploiting the ability of SiC semiconductor devices to operate at temperatures, breakdown voltages, and current densities significantly greater than those of conventional Si devices, the designs of SiC MCPMs and of systems comprising multiple SiC MCPMs are expected to afford a greater degree of miniaturization through stacking of modules with reduced requirements for heat sinking. Moreover, the higher-temperature capabilities of SiC MCPMs could enable operation in environments hotter than Si-based power systems can withstand.

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