Abstract: A chopper for an imaging system includes a frame and a sheet that have different coefficients of thermal expansion. The frame has a space within it, and has at least one opening that allows radiation to pass through the space. The sheet has structure which influences radiation passing through the sheet, and the sheet is movably disposed within the space in the frame, in a manner so that the sheet can expand and contract relative to the frame in a direction approximately parallel to the sheet. The frame prevents any significant movement of the sheet in a direction transverse to the sheet.

Abstract: A multi-stage variable gain amplifier is disclosed that utilizes overlapping gain curves to compensate for log-linear errors. Each gain stage is configured to approximate a log-linear response with a sinusoidal error term such that a portion of the curve has positive errors and a portion of the curve has negative errors. In operation, the control signal inputs for the gain stages are driven such that the gain curves overlap and positive errors in each stage are offset by negative errors in the adjacent stage. The resulting combined gain is a more log-linear response.

Abstract: Several open-loop calibration techniques for phase-locked-loop circuits (PLL) that provide a process, temperature and divider modulus independence for the loop bandwidth and damping factor are disclosed. Two categories of open-loop techniques are presented. The first method uses only a single measurement of the output frequency from the oscillator and adjusts a single PLL loop element that performs a simultaneous calibration of both the loop bandwidth and damping factor. The output frequency is measured for a given value of the oscillator control signal and the charge-pump current is adjusted such that it cancels the process variation of the oscillator gain. The second method uses two separate and orthogonal calibration steps, both of them based on the measurement of the output frequency from the oscillator when a known excitation is applied to the open loop signal path.

Abstract: Systems and methods for analog to digital conversion that may be implemented using a digital to analog converter (DAC) to provide negative feedback to at least Partially cancel one or more signals (e.g., one or more interfering signals present with one or more desired signals, one or more strong desired signals, etc.) at the analog input of an analog to digital converter (ADC), and that may be used to extend the effective dynamic range of an ADC. The effective dynamic range of an ADC may be extended by detecting and isolating signals and using digital adaptive digital filtering along with a digital to analog converter (DAC) to provide negative feedback to cancel the signal/s at the input of the ADC.

Abstract: A communication isolation system is provided that may employ error correction techniques for the data communicated across an isolation barrier used for connecting electronic circuitry to a communication line. In one embodiment, each data bit to be transmitted to or from the phone line may be transmitted three times across an isolation barrier so that it is possible to withstand a single electronic fast transient event. In another embodiment, the isolation barrier may be a capacitive isolation barrier. In another embodiment, the three transmissions of the data bit may be received across the isolation barrier and delay elements utilized to provide the data bits to a logic circuit in a synchronized fashion so that the three data bits may be compared to determine the error corrected data.

Abstract: An apparatus for scheduling transmission of a plurality of frames in a network having a plurality of nodes, each frame identified by a type designation, includes a schedule memory and a sequencer. The schedule memory stores a transmission time for each frame type and a list of frames to be transmitted. The sequencer is operable to access the schedule memory and initiate transmission of the frames in the list.

Abstract: A method of preparing and operating a subsea well (23), comprising the steps of: locating a drill-through subsea tree (24) on a subsea wellhead; sealingly connecting a high pressure drilling riser (22) between the tree and a drilling platform at the sea surface; mounting a blow out preventer (16) at the top of the riser (22); drilling the well through the drilling riser and the subsea tree; and establishing a production connection between the tree (24) and a production collection facility at the sea surface through a production riser (52) which is separate from the drilling riser (22).

Abstract: An electromagnetic circuit that may be advantageously employed in an articulated camera, such as a CCTV camera, as a part of a servo mechanism to directly drive the camera and optical lens assembly, for example, in the pan and/or tilt axes. In one embodiment, the coil assembly of the servo mechanism may comprise four separate coils that rotate about the center of the ring shape of a single one-piece ring-shaped permanent magnet that has been pre-magnetized in two pair of opposing polarities. The magnet assembly that includes the magnet ring, may be bonded to a circular plate made of ferrous metal.

Abstract: A write protection mechanism may be implemented that is external to a non-volatile memory device and/or that is external to controller/s that interface with the non-volatile memory device, thus providing increased security over unauthorized and/or undesirable write cycles to the memory device. Write protection security may be further enhanced by providing a write protection control signal that is external to the non-volatile memory and attached memory controller/s, thus preventing accidental or intentional override.

Abstract: An isolation system is provided that is suitable for use in telephony, medical instrumentation, industrial process control and other applications. Preferred embodiments of the invention comprise a capacitive isolation barrier across which a digital signal is communicated. The system provides a means of communication across the isolation barrier that is highly immune to amplitude and phase noise interference. Clock recovery circuitry may be employed on one side of the isolation barrier to extract timing information from the digital signal communicated across the barrier, and to filter the effects of phase noise introduced at the barrier. Delta-sigma converters may be disposed on both sides of the isolation barrier to convert signals between analog and digital domains. An isolated power supply may also be provided on the isolated side of the barrier, whereby direct current is generated in response to the digital data received across the isolation barrier.

Abstract: A spectroscopy system is provided which operates in the vacuum ultra-violet spectrum. More particularly, a system utilizing reflectometry techniques in the vacuum ultraviolet spectrum is provided for use in metrology applications. The system may further include the use of an array detector in combination with an imaging spectrometer. In this manner data for multiple wavelengths may be simultaneously collected. Moreover, the multiple wavelengths of data may be collected simultaneously for a two dimensional sample area. The system may further include the use of a fixed diffraction grating and does not require the use of polarizing elements. To ensure accurate and repeatable measurement, the environment of the optical path is controlled. The optical path may include a controlled environmental chamber in which non-absorbing purge gases are present or in which vacuum evacuation techniques are utilized. The controlled environment may further include a separate instrument chamber and a separate sample chamber.

Abstract: An improved digital capacitive isolation barrier system is provided that is suitable for use in a telephone or modem where the locally powered circuits must be effectively isolated from the public telephone system, while permitting data transfer across the barrier. In particular, an automatic ADC offset calibration system is provided for determining the magnitude of the ADC offset signal required in the system during a calibration operation, and for providing the calibrated ADC offset signal during normal operation of the isolation barrier system. A modified hybrid circuit is provided for isolating the system input from the telephone line during calibration, and for completing the calibration loop. Fixed bias signals are also provided for the ADC and for a DAC in the system. In a preferred embodiment, the ADC is located on the isolated side of the isolation barrier, while the integrator and register that determine and hold the offset signal are located on the powered side of the isolation barrier.

Abstract: A digital direct access arrangement (DAA) circuitry may be used to terminate the telephone connections at the user's end that provides a communication path for signals to and from the phone lines. Briefly described, the DAA provides a programmable means for the DC termination for a variety of international phone standards. The invention may also be utilized with means for transmitting and receiving a signal across a capacitive isolation barrier. More particularly, a DC holding circuit is provided in which a programmable DC current limiting mode is available. In the current limiting mode, power may be dissipated in devices external to a DAA integrated circuit. Moreover, much of the power may be dissipated in external passive devices, such as resistors.

Abstract: A digital direct access arrangement (DAA) circuitry may be used to terminate the telephone connections at the user's end to provide a communication path for signals to and from the phone lines. Briefly described, a means for providing a proper hookswitch transition for a variety of international phone standards is provided. The invention may also be utilized with means for transmitting and receiving a signal across a capacitive isolation barrier. More particularly, a DAA circuitry may be utilized which satisfies many or all hookswitch transition standards without the use of additional discrete devices. The hookswitch transition standards may be satisfied by ramping down the current flowing through the hookswitch prior to transitioning the hookswitch state. In this manner the hookswitch current change as a function of time (di/dt) may be decreased. Thus, the current through the hookswitch may be actively controlled prior to switching the hookswitch from an off-hook condition to an on-hook condition.

Abstract: This invention concerns an epoxy coating for use as a non-skid surface for applications such as the deck of an aircraft carrier. The epoxy coating can be formulated from (a) an amine curing agent, (b) an epoxide-containing toughening agent such as a polysulfide and/or a polythioether, (c) an epoxy resin, (d) a rubber toughening agent, and (e) an optional fire retardant, a glass fiber thixotrope and impact toughening agent, an optional pigment, an optional corrosion inhibitor, an optional moisture penetration inhibitor, an optional ultraviolet light stabilizer, an optional abrasive aggregate, or a combination thereof.

Abstract: A radio-frequency (RF) apparatus includes front-end circuitry. The front-end circuitry includes a filter circuitry and an impedance matching circuitry. The filter circuitry has a differential output that has an output impedance. The filter circuitry filters signals outside a signal band of interest. The impedance matching network has a differential input coupled to the output of the filter circuitry. The impedance matching network also has a differential output coupled to a signal processing circuitry. The signal processing circuitry has an input impedance. The impedance matching network matches the input impedance of the signal processing circuitry to the output impedance of the filter circuitry.

Abstract: Frequency modification circuitry may be employed as part of a crystal oscillator circuit to generate a reference signal with adjustable frequency. The frequency modification circuitry may be implemented as part of a crystal oscillator circuit that includes digitally controlled crystal oscillator (“DCXO”) circuitry and a crystal. The frequency modification circuitry may adjust the frequency of the reference signal in response to one or more frequency control signals. In one example, the frequency modification circuitry may include variable capacitors such as one or more continuously variable and/or discretely variable capacitors for providing coarse and/or fine adjustment of the reference signal frequency.

Abstract: A calibration circuitry includes an adjustable capacitor, a voltage generator, a reference voltage generator, and a controller. The reference voltage generator provides a reference voltage. The voltage generator provides a measurement voltage that depends on the capacitance of the adjustable capacitor. The capacitance of the adjustable capacitor varies in response to a control signal. The controller provides the control signal based on the relative values of the reference voltage and the measurement voltage.

Abstract: A spectroscopy system is provided which operates in the vacuum ultraviolet spectrum. More particularly, a system utilizing reflectometry techniques in the vacuum ultraviolet spectrum is provided for use in metrology applications. To ensure accurate and repeatable measurement, the environment of the optical path is controlled to limit absorption effects of gases that may be present in the optical path. The VUV reflectometer may be utilized to monitor a wide range of data in a semiconductor processing environment. For example, the techniques may be used for measuring thicknesses, optical properties, composition, porosity and roughness of a film or stack of films. Further, the VUV techniques and apparatus may be used to characterize critical dimensions and other features of a device. The VUV reflectometer system may be utilized as a stand alone tool, or the relatively compact nature of the system may be taken advantage of such that the system is incorporated into other process tools.

Abstract: A quick startup procedure for a modem system utilizes known characteristics of a previously established communication channel to reduce the initialization period associated with subsequent connections over the same channel. In response to the establishment of a call, the modem devices determine whether the quick connect protocol is supported. If so, then the called modem transmits a modified answer tone to the calling modem. The calling modem analyzes the signal received in response to the modified answer tone to determine whether characteristics of the current channel are similar to stored characteristics associated with a previous connection over the same channel. If a channel “match” is found, then the modem devices carry out a quick initialization routine that eliminates, abbreviates, or modifies a number of procedures or protocols that are carried out in conventional modem startup processes.