Abstract: Switched-capacitor structures are provided that reduce distortion and noise in their processed signals because they increase isolation between structural elements and ensure that selected elements are securely and quickly turned off and on in different modes.

Abstract: An equipment mounting rack is composed of a seismically sound skeleton structure having spaced vertical uprights supplemented by distinct spaced equipment mounting structures attached to that skeleton structure and extending along these vertical uprights and constituting side wall structures of a mounting rack interior space. The distinct spaced equipment mounting structures may have elongate first sections extending along the spaced vertical uprights, and elongate second sections extending along these first sections and constituting side wall structures of a mounting rack interior space. Cabinet walls may be attached to the skeleton structure, and the equipment mounting structures may constitute inside such cabinet walls side wall structures of a mounting rack interior space. The vertical uprights advantageously are reinforced by elongate partial enclosures that may avoid the need for a large number of weakening mounting holes in these uprights.

Abstract: Self-calibration methods and structures are provided for pipelined ADCs which can be realized without requiring external measuring instruments or calibrators, without requiring major changes in pipeline structure and which can be rapidly obtained with stored calibration processes. In method embodiments, each of selected converter stages are calibrated by using succeeding stages as sub-ADCs which measure gain error at a transition step in a selected stage's residue transfer characteristic and saves the gain error as a calibration constant Ccal for that stage. After a first calibration constant Ccal has been obtained, the process is successively repeated for preceding converter stages except that previously-obtained calibration constants are multiplied by their respective stage's digital input signals Din to obtain weighted calibration constants Ccalwtd which are included in measured gain errors to thereby obtain preceding calibration constants Ccal.

Abstract: Direct-coupled laser diode drivers are provided which eliminate the need for conventional coupling elements (e.g., capacitors and inductors) that typically introduce timing inacurracies and add complexity, size and cost to conventional drivers. The drivers are structured to reduce power dissipation and maintain sufficient transistor headroom to enhance response time and dynamic range. An exemplary driver responds to data pulses that are defined by first and second pulse levels and includes a current source that generates an imod/n current, a current mirror connected to receive the imod/n current and, in response, drive a modulation current imod through the laser diode and a differential pair of transistors that steers the imod/n current away from the modulation current mirror in response to the first pulse levels so that the modulation current mirror drives imod current pulses through the laser diode during the second pulse levels with no need for coupling elements.

Abstract: A crutch constructed of two adjacently located, elongated, parallel upper and lower bows which can be moved in relationship to each other to form a vertical support of readily varied length. These bows have the same design and are therefore interchangeable, significantly reducing inventory requirements. Each bow has a series of parallel horizontal notches with the bows positioned so that the notches on each bow are on contacting surfaces. A pin inserted into parallel, adjacent notches on the two bows in cooperation with two or more collars or caps on the ends of one end of each bow fixes the relationship between the shafts which, in turn, defines the length of the vertical support. A similar concept can be used to lock a moveable centrally located lower bow between two parallel outer upper bows. This assemble provides a strong, adjustable length crutch for any height patient using only two different pairs of bow lengths.

Abstract: Latch structures and systems are disclosed that enhance latch speed and reduce latch current drain while providing complementary metal-oxide-semiconductor (CMOS)-level latch signals. They are realized with bipolar junction structures and CMOS structures that are arranged to limit latch currents in response to CMOS-level sense signals Ssns.

Abstract: Amplifier systems and methods are provided which closely approximate a constant output impedance and a constant quiescent output signal during forward and reverse modes of operation. The systems can be realized with small, inexpensive components that are compatible with integrated-circuit fabrication processes. A system embodiment includes a signal amplifier, a feedback path that is coupled across at least part of the signal amplifier to reduce its impedance, a reverse amplifier which is coupled to drive at least a feedback portion of the feedback path and a signal generator which controls operational timing of the signal amplifier and reverse amplifier. Another system embodiment includes an error-current canceler that cancels error currents of the signal amplifier with substantially equal and opposite correction currents.

Abstract: A four current transistor temperature sensor comprises a p-n junction, preferably the base-emitter junction of a bipolar transistor, which is driven with four different currents in a predetermined sequence. Each of the four currents induces a respective base-emitter voltage, which is measured. The temperature of the transistor is calculated based on the values of the four driving currents and the four measured base-emitter voltages. The four driving currents (I1, I2, I3 and I4) are preferably arranged such that I1=2*I3, I2=2*I4, I1/I2=A and I3/I4=A, where A is a predetermined current ratio. I1 and I2 produce respective base-emitter voltages which are subtracted from each other to produce &Dgr;Vbe1, and I3 and I4 produce respective base-emitter voltages which are subtracted from each other to produce &Dgr;Vbe2. When so arranged, the difference between &Dgr;Vbe1 and &Dgr;Vbe2 is entirely due to the effect of series base and emitter resistances rb and re.

Abstract: Local-oscillator systems for wireless communication systems are realized with oscillator networks that are phase locked to a bit timing clock. Two of the networks provide first and second phase coherent local-oscillator signals respectively to a receiver and transmitter of a transceiver. A third oscillator system forms a phase lock loop about one of the other networks and preferably includes a crystal to enhance short term stability. Because they track the bit timing clock, the first and second local-oscillator signals phase track all communication signals in the transceiver's communication system.

Abstract: Feedback control loop systems are provided that enhance output-signal switching times without degrading other loop performance parameters. The systems reduce “kick-back” voltages that are generated in a loop filter by drive currents which rapidly drive a control loop oscillator to a loop acquisition range. This reduction reduces a frequency step in the oscillator output signal which would otherwise have to be driven to eliminate the frequency step with a consequent increase in the output-signal switching time. Structures are provided that reduce the kick-back voltage to thereby enhance output-signal switching times.

Abstract: A blade and a blade assembly wherein the blade has a front, beveled, sharpened edge, two side edges meeting at a point spaced from the front edge and at least one attachment structure extending outwardly from each side edge. A blade holder, which extends beyond the side edges and attachment structures of the blade, sits on a top surface of the blade and is attached to the blade by a portion thereof which receives the attachment structures. The holder has an opening in an exposed surface to receive an extension from a drive mechanism such that when the drive mechanism is activated the blade is caused to vibrate or oscillate. The blade is oscillated in a lateral fashion when driven by a rod rotating along a circular path.

Abstract: An embedded real time diagnostic system that is applicable to fault detection and isolation in host systems having repetitive subsystems. A query directed acyclic graph (Q-DAG) for one of each type of repetitive subsystem is compiled off-line from a causal network model and is stored in host system computer memory. When a fault in the host system is detected by the computer, a replicating program replicates the necessary subsystem Q-DAGs to construct an overall host system Q-DAG. A data table which contains information on how the various Q-DAGs are linked based on the hardware architecture of the host system, is also accessed by the computer. The data table contains a matrix which dictates which Q-DAGs are linked, and Q-DAG level information on the Q-DAG nodes and which nodes are linked to nodes in other Q-DAGs. The new diagnostic system uses less memory and processor throughput while still providing full system diagnostics.

Abstract: A phase inversion prevention circuit for an op amp input stage includes a detection circuit which detects when either of the input pairs' intrinsic diodes is near a forward-biased condition. When such a condition is detected, a switching network switches tail current from the primary input pair to a secondary input pair which takes over the input stage's amplifying duties. For a folded cascode input stage, the detection circuit preferably detects the onset of phase inversion by monitoring the cascode voltage which drives the cascode transistors. The outputs of the secondary input pair are connected to bypass the cascode transistors. Thus, when the onset of phase inversion is detected, the primary input pair is disabled, the second input pair is enabled, and with the cascode transistors bypassed the secondary input pair avoids phase inversion.

Abstract: An apparatus and method monitors the condition of a bearing/shaft assembly by forming diagnostics based on spectral analysis of assembly's vibration. Baseline parameters are determined by a microprocessor analysis of the vibration spectra, comparing actual peaks to the peaks predicted by a model. The microprocessor estimates rotation rate and preferably number of rolling elements by attempting to fit the model to the actual vibrational spectrum, by varying the assumptions. Baseline profiles are formed from one or more selected tones and preferably also harmonics thereof, to characterize the bearing/shaft assembly. The baseline profiles and parameters are compared against later acquired vibrational characteristics, and the comparison is used to diagnose bearing and/or shaft conditions.

Abstract: An equipment mounting rack is composed of a seismically sound skeleton structure having spaced vertical uprights supplemented by distinct spaced equipment mounting structures attached to that skeleton structure and extending along these vertical uprights and constituting side wall structures of a mounting rack interior space. The distinct spaced equipment mounting structures may have elongate first sections extending along the spaced vertical uprights, and elongate second sections extending along these first sections and constituting side wall structures of a mounting rack interior space. Cabinet walls may be attached to the skeleton structure, and the equipment mounting structures may constitute inside such cabinet walls side wall structures of a mounting rack interior space. The vertical uprights advantageously are reinforced by elongate partial enclosures that may avoid the need for a large number of weakening mounting holes in these uprights.

Abstract: Transimpedance amplifiers are provided that generate low-distortion output voltage signals with simple, inexpensive structures that are compatible with integrated-circuit fabrication processes. The amplifiers include a current processor and a complementary output stage. The processor provides in-phase upper and lower current signals in response to a differential input current signal and differentially alters respective first and second amplitudes of these signals in response to a common-mode input current signal. The complementary output stage has upper and lower transistors that provide the output voltage signal in respective response to the upper and lower current signals and with distortion that is reduced by the altered first and second amplitudes.

Abstract: Feedback methods and systems are provided to achieve rapid switching of oscillator frequencies without compromising operational feedback loop bandwidths that filter out spurious tones and phase noise to thereby enhance loop spectral and noise performance. The methods respond to frequency changes in a reference signal by providing an open-loop drive current to drive a feedback signal towards the reference signal. The drive current is terminated and the feedback control loop closed when the feedback signal is within a predetermined acquisition range of the reference signal. This is determined by successively comparing a feedback frequency of the feedback signal to a destination frequency of the reference signal over a comparison window of time. The invention also provides a feedback control system that practices the invention's methods.

Abstract: A bipolar rail-to-rail input stage includes complementary differential input pairs, and a switching circuit which makes one or the other of the input pairs active depending on the relationship between a transition threshold voltage Vth and the common mode input voltage Vcm. A transition threshold voltage selection circuit provides a selectable one of at least two different Vth voltages to the switching circuit in response to a select signal. In one embodiment, the select signal has logic “high”, logic “low”, and “floating” states. The transition threshold voltage selection circuit provides a first Vth voltage when the select signal is in a first state, a second Vth voltage when the select signal is in a second state, and disables the input stage when the select signal is in a third state.

Abstract: An equipment mounting rack is composed of a seismically sound skeleton structure having spaced vertical uprights supplemented by distinct spaced equipment mounting structures attached to that skeleton structure and extending along these vertical uprights and constituting side wall structures of a mounting rack interior space. The distinct spaced equipment mounting structures may have elongate first sections extending along the spaced vertical uprights, and elongate second sections extending along these first sections and constituting side wall structures of a mounting rack interior space. Cabinet walls may be attached to the skeleton structure, and the equipment mounting structures may constitute inside such cabinet walls side wall structures of a mounting rack interior space. The vertical uprights advantageously are reinforced by elongate partial enclosures that may avoid the need for a large number of weakening mounting holes in these uprights.

Abstract: A voltage mode digital-to-analog converter (DAC) with an output buffer operational amplifier is provided with a rail-to-rail output voltage capability by reducing the DAC's output voltage swing to a range that is within the amplifier's permissible input signal range, and connecting the amplifier in a multiplier configuration to produce a corresponding multiplication of its input signal. The DAC output reduction is preferably achieved by delivering an n-bit input digital signal to an n+m bit DAC, and holding the DAC's m most significant bits OFF. The m most significant bits are dummy bits that are impedance matched with the DAC, while the amplifier is an operational amplifier with a feedback circuit that is also impedance matched to the DAC.