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Standard dosimeter reader, modified by adding an electronic gating circuit to trigger the intensity level photomultiplier, increases readout sensitivity of photoluminescent dosimeter systems. The gating circuit is controlled by a second photomultiplier which senses a short ultraviolet pulse from a laser used to excite the dosimeter.
Metal-oxide semiconductor field-effect transistor /MOSFET/ analog-gate circuit adapts well to integrated circuits. It provides better system isolation than a transformer, while size and weight are appreciably reduced.
Commercially available integrated circuit that is marketed as a digital computer input gate circuit was converted to a linear amplifier in a microphone circuit that has high input impedance, low output impedance, low cost, and is small enough to fit on a standard printed circuit card.
Nanosecond pulse low power amplitude-to-time converter and associated linear gate circuits
A gate drive circuit includes an insulated gate semiconductor switch. A controlled current source is connected to the semiconductor switch gate terminal to provide a gate drive circuit that is responsive to recycled gate charge corresponding to an internal gate capacitance of the insulated gate semiconductor switch.
A gate drive latching circuit for an auxiliary resonant commutation circuit for a power switching inverter includes a current monitor circuit providing a current signal to a pair of analog comparators to implement latching of one of a pair of auxiliary switching devices which are used to provide commutation current for commutating switching inverters in the circuit. Each of the pair of comparators feeds a latching circuit which responds to an active one of the comparators for latching the associated gate drive circuit for one of the pair of auxiliary commutating switches. An initial firing signal is applied to each of the commutating switches to gate each into conduction and the resulting current is monitored to determine current direction and therefore the one of the switches which is carrying current. The comparator provides a latching signal to the one of the auxiliary power switches which is actually conducting current and latches that particular power switch into an on state for the duration of current through the device. The latching circuit is so designed that the only time one of the auxiliary switching devices can be latched on is during the duration of an initial firing command signal.
A power converter apparatus comprises a set of switching elements communicatively coupled with a set of gate drive circuits. Each gate drive circuit is configured to provide a respective drive signal to a corresponding switching element, each switching element being switchably responsive to the respective drive signal. The apparatus includes a controller module configured to control an output state of the power converter, and selectively change one of a respective gate resistance and a respective gate current of a corresponding subset of the gate drive circuits based on the output state of the power converter.
Circuit proposed to recover energy usually lost in charging and discharging internal gate capacitance of field-effect transistor during high-frequency switching. Scheme includes pulse-forming circuit generating rectangular waveform with zero-level notches near beginning and end of "on" period. Inductor resonates internal gate capacitance so energy recovered during notches.
Design procedure for production of radiation resistant NOR gate logic circuit
The project goal was to research, design and fabricate high-power-density, high-performance SiC power electronic modules for motor drive inverters in electric vehicles (EVs) to enable the subsequent motor drive to achieve a power density of 100 kW/l. EVs use electric motors instead of internal combustion engines as the prime mover, and their core components are semiconductor-based power electronic modules. Efficient power electronic modules play a vital role in power conversion systems. The performance of power modules directly affects the energy efficiency and overall performance of electric vehicles. Therefore, it is particularly important to develop power modules with high power density and high electrical performance that will perform reliably under EV environmental conditions. To achieve these goals, advanced electronic packaging technologies are required. This report describes a 5-year effort to integrate key aspects surrounding the basic power devices into the module itself to increase power density. These include sensing and sensing readout circuits, gate driver circuits, and two-sided cooling solutions.
Low power NAND gate integrated circuit employing thin film resistors and lateral p-n-p transistors
A very low power frontend circuit using the compensating common-gate scheme is described. It combines features of the regular common-gate topology and the trans-impedance amplifier (TIA) schemes allowing designers to achieve low input impedance and sufficient bandwidth with small power consumption. It can be used as an interface between detectors and the pseudo-thyristors we developed to complete a full frontend signal chain. Simulation shows that in a 65 nm process, it is possible to achieve an input impedance <1K Ohms allowing a charge detection <6fC with 3pF parasitic capacitance, using static power below 20 micro-Watts/channel.
Three nand gate circuits are used to add error detection and reset logic circuitry for initiating and retaining the correct binary state in the flip-flop circuits of a ring counter. As the input signals are counted, the position of the specified state moves in ordered sequence around circuit loop.
With the increased usage of SiC and GaN devices in power converters, it is apparent to engineers that the benefits of these devices for low switching losses have to be balanced against two deterrents: (1) the faster rise and fall times of these devices lead to increased harmonic content, making it more difficult to meet Electromagnetic Compatibility (EMC) regulations; and (2) increased sensitivity to parasitic elements in the board layout, leading to higher dv DS /dt and di D /dt with higher current and voltage peak stresses. "Active" gate drives are thus needed to regulate different regions of switching to achieve the optimal tradeoff between switching loss and EMC. We present a simple analog circuit architecture for an active gate drive. Turn on and turn off tests with SiC modules and discrete parts are discussed with experimental results.
A liquid helium-cooled infrared spectrometer for the 16 to 50 micron range is described. The instrument has six detectors, three each of Si:Sb and Ge:Ga and two diffraction gratings mounted back-to-back. Cold preoptics are used to match the spectrometer to the telescope. In its nominal configuration the system resolution is 0.03 micron from 16 to 30 microns and 0.07 micron from 28 to 50 microns. A cooled filter wheel is used to change order sorting filters. The gratings are driven by a steel band and gear train operating at 4 K. The detector outputs are amplified by a TIA, employing a matched pair of JFETs operating at 70 K inside the dewar. The external warm electronics include a gain stage for the TIA and dc-coupled gating circuit to remove charged-particle (cosmic-ray secondary)-induced noise spikes. The gating circuit reduces the overall system noise by a factor of two when the spectrometer is used on NASA's Kuiper Airborne Observatory. Sample spectra are presented and the deglitcher performance is illustrated.
The ability to detect uranium (U) through environmental monitoring is of critical importance for informing water resource protection and nonproliferation efforts. Although technologies exist for environmental U detection, wide-area environmental monitoring, i.e. sampling coverage over large areas not known to possess U contamination, remains a challenging prospect that necessitates the development of novel detection approaches. In this work, we describe the development of a whole-cell U sensor by integrating two functionally independent, native U-responsive two-component signaling systems (TCS), UzcRS and UrpRS, within an AND gate circuit in the bacterium Caulobacter crescentus. Through leverage of the distinct but imperfect selectivity profiles of both TCS, this combinatorial approach enabled greater selectivity relative to a prior biosensor developed with UzcRS alone; no cross-reactivity was observed with most common environmental metals (e.g, Fe, As, Cu, Ca, Mg, Cd, Cr, Al) or the U decay-chain product Th, and the selectivity against Zn and Pb was significantly improved. In addition, integration of the UzcRS signal amplifier protein UzcY within the AND gate circuit further enhanced overall sensitivity and selectivity for U. The functionality of the sensor in an environmental context was confirmed by detection of U concentrations as low as 1 μM in groundwater samples. The results illustrate the value of a combinatorial approach for constructing whole-cell sensors for the selective detection of analytes for which there are no known evolved regulators.
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