Semiconductors & ICs

G4-FETs as Universal and Programmable Logic Gates

Logic functions could be implemented using fewer active circuit elements. An analysis of a patented generic silicon-on-insulator (SOI) electronic device called a G4-FET has revealed that the device could be designed to function as a universal and programmable logic gate. The universality and programmability could be exploited to design logic circuits containing fewer discrete components than are required for conventional transistor-based circuits performing the same logic functions.

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Improved On-Chip Measurement of Delay in an FPGA or ASIC

Input and output buffers and the associated delays are eliminated. An improved design has been devised for on-chip-circuitry for measuring the delay through a chain of combinational logic elements in a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC). Heretofore, it has been the usual practice to use either of two other types of on-chip delay-measuring circuits: A delay chain of inverters is incorporated into the FPGA or ASIC chip along with an input port for feeding the inverter chain and an output port for feeding a signal to off-chip measurement circuitry. The disadvantage of this design is that the measurement is inaccurate because it includes delays in buffers that are parts of the input and output ports. The delay chain is arranged as a ring oscillator. The disadvantage of this design is that the delay chain does not always oscillate as expected.

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Integrated Radial Probe Transition From MMIC to Waveguide

Packaging based on wire bonding would be supplanted by monolithic integration. A radial probe transition between a monolithic microwave integrated circuit (MMIC) and a waveguide has been designed for operation at frequency of 340 GHz and to be fabricated as part of a monolithic unit that includes the MMIC. Integrated radial probe transitions like this one are expected to be essential components of future MMIC amplifiers operating at frequencies above 200 GHz. While MMIC amplifiers for this frequency range have not yet been widely used because they have only recently been developed, there are numerous potential applications for them — especially in scientific instruments, test equipment, radar, and millimeter- wave imaging systems for detecting hidden weapons.

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MMIC Amplifier Produces Gain of 10 dB at 235 GHz

This is the fastest MMIC amplifier reported to date. The first solid-state amplifier capable of producing gain at a frequency >215 GHz has been demonstrated. This amplifier is an intermediate product of a continuing effort to develop amplifiers having the frequency and gain characteristics needed for a forthcoming generation of remote-sensing instruments for detecting water vapor and possibly other atmospheric constituents. There are also other potential uses for such amplifiers in wide-band communications, automotive radar, and millimeter- wave imaging for inspecting contents of opaque containers.

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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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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).

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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).

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