摘要:
A circuit for protecting a CMOS device against execssive voltages has two SCR circuits in which the bipolar transistors are formed as parasitic devices. One SCR circuit is connected between a line to be protected and one power supply point and the other SCR circuit is connected between the line to be protected and the other power supply point. The power supply points form sinks for currents associated with excessive voltages, and they form reference potential points for establishing the voltage at which an SCR turns on. A semiconductor device having an n-substrate has three p-wells. The center p-well (as seen in section) forms part of two vertical transistors, one for each of the two SCR's. Each outer p-well cooperates with the center p-well and the intervening substrate to form a lateral transistor for one of the SCR's. These transistors use shared semiconductor regions that establish the base to collector interconnections of an SCR. These regions and other structures also form an FET and a diode in each SCR circuit that turn on the SCR in response to an excessive voltage.
摘要:
A system for recovering a clock signal from a data signal is described. The system uses an oscillator adapted to generate an oscillator output signal, a first detecting circuit for obtaining a coarse frequency-lock condition between the data signal and a recovered clock signal, a second detecting circuit for obtaining a phase-locked condition between the data signal and the recovered clock signal, a lock-detecting circuit responsive to the first detecting circuit for detecting an out-of-lock condition between the data signal and the recovered clock signal, and a control circuit responsive to the lock-detecting circuits and adapted to control the oscillator to generate an oscillator output signal on the basis of the first detecting circuit during an out-of-lock condition, and otherwise to generate the oscillator output signal on the basis of the second detecting circuit. The advantages include a much wider pull-in range for frequency acquisition, and an accurate and robust measure of a quality of received data.
摘要:
A method of flank milling complex surfaces comprising the steps of analyzing the design surface to determine discrete areas in which straight lines can be drawn, determining straight lines in the discrete areas, transposing the coordinates of these straight lines and comparing them with the flank tool cutter positions, determining the tool positions to said straight lines, back generating the contact lines of said surface and comparing these with the design surface, determining the number of passes of said cutter tool and generating data for numerical control machining.
摘要:
A method of machining an airfoil includes the steps of providing first and second cutting tools respectively having first and second cutting contours that are different than one another. A blank is cut with the first cutting tool to provide a first airfoil surface on a first blade. The blank is cut with the second cutting tool to provide a second airfoil surface on a second blade. An airfoil is produced having the first and second blades. A cutting tool for machining the airfoil includes a shank. A cutting surface adjoins the shank and provides a cutting contour corresponding to an airfoil surface. The cutting surface extends along a cutting length axially from a nose to near a cutting boundary. The cutting length is configured to be greater than the blade length.
摘要:
A method and apparatus for performing optical channel performance management on a WDM system while in operation is disclosed in which each transmitter and receiver uses forward error-correction schemes to improve the BER performance of the channel in a known relation to the performance before error-correction. The receiver measures the BER performance before error-correction in real-time and communicates it to a system manager which determines, from this data, the appropriate launch power of each transmitter in the system, which it commands each transmitter to adopt, thereby ensuring relative launch powers which optimize the overall BER performance of the WDM multiplexed signal.
摘要:
A method of machining an airfoil includes the steps of providing first and second cutting tools respectively having first and second cutting contours that are different than one another. A blank is cut with the first cutting tool to provide a first airfoil surface on a first blade. The blank is cut with the second cutting tool to provide a second airfoil surface on a second blade. An airfoil is produced having the first and second blades. A cutting tool for machining the airfoil includes a shank. A cutting surface adjoins the shank and provides a cutting contour corresponding to an airfoil surface. The cutting surface extends along a cutting length axially from a nose to near a cutting boundary. The cutting length is configured to be greater than the blade length.
摘要:
The present invention relates to a quill to be used to superabrasively machine complex shapes, such as airfoil shapes, into a substrate. The quill has a shaft portion, an enlarged head portion adjacent the shaft portion, and a tapered grinding portion adjacent the enlarged head portion. The tapered grinding portion has a layer of grit material selected from the group consisting of diamonds and cubic boron nitride thereon. In a preferred embodiment, the quill is a vitrified or plated cubic boron nitride quill on the grinding portion. A method of using the tool is also disclosed.