Abstract: An electrical overstress power protection device consists of a diode limiter array and an input and output electrical matching network. All of these functions are integrated monolithically on a single semiconductor chip which allows ease of use, small size, and high frequency operation. The device is used to protect instrument input and output circuitry from damage.

Abstract: A module technology allows a PGA like package architecture to be used in microwave instruments and other high frequency systems where high isolation, low reflection, and low cost multi-chip modules are needed.

Abstract: In the present embodiment, digital phase detection of digital telecommunications signals is based on heterodyning. The frequency of two signals are scaled to different nominal values that are separated by a typically small but finite difference. The two frequencies are then mixed to generate a finite beat frequency. In mixing, phase is preserved and the finite beat frequency phase is in one-to-one correspondence with the signal phase. Phase detection is performed indirectly at the lower finite beat frequency with high resolution and greater ease than direct phase detection.

Abstract: A hybrid printed circuit board comprising two substrates having different thermal coefficients of expansion can be manufactured using automated surface mount techniques. A daughterboard is configured with a number of contact pads on the bottom. A motherboard is configured with an aligned set of contact pads on the top with solder compound stenciled on them. The daughterboard is attached to the motherboard using standard automated surface mount techniques.

Abstract: A capacitive sensor for detecting the amount of residual ink remaining within an ink container of an ink jet cartridge by measuring the capacitance of the air dielectric between the ink bag and the ink cartridge.

Abstract: A master and a slave digital frequency synthesizer are phase-locked such that the master synthesizer is always selected to minimize the phase hits which occur when switching the master to be a slave and vice versa. The switching rearrangement is done automatically and rapidly in the event of failure of the master frequency synthesizer.

Abstract: A distributed adaptable measurement network, which has flexible sensor or actuator nodes, takes multiple single valued measurements, such as temperature, pH, density, turbidity, velocity, breakdown strength, and strain as a function of time. The network can control large scale physical processes in response to these measurements. The flexible sensor or actuator node uses interchangeable common core modules, where each common core module uses a common description for data configuration and control of the measurement and response parameters. Although many physical variables can be affected, each variable is controlled in the same fashion. A transducer module selects the physical variable to which the common core module will be sensitive and whether its role will be that of a sensor or an actuator. The network may also contain system transducers which can control or alter the initial measurement and response parameters selected by the transducer module.

Abstract: An image with increased sensitivity to non-linear responses, particularly second harmonic responses, can be achieved by measuring the ultrasound response under multiple excitation levels. The responses gathered from the multiple excitation levels are gain corrected in an amount corresponding to the difference in excitation levels, then subtracted. Because of this subtraction, most of the linear response will be removed, and what remains corresponds to the non-linear response.

Abstract: A frequency response of a pneumatic system used to control a gas chromatograph may be determined by applying a loop-closed direct method. The loop-closed direct method can be used to describe a frequency response of a time-invariant, linear system and predicting the system stability for any input signal. The transfer function which describes the frequency response is used by a microprocessor to control the physical parameters of the pneumatic system in terms of pressure and flow.

Abstract: The local clocks within each node of a loosely distributed network system may be synchronized and syntonized by any of the nodes in the network. Each of the nodes contains a time packet detector (TPD) that detects and recognizes timing data packets and produces a recognition signal. This signal may be used to cause an action in the detecting node, in particular the node may contain a time service block (TSB) containing a local clock that may be used to record the time of the recognition signal. The recorded times may be used as the basis for correcting the local clocks of the nodes in the system. Transfer devices such as gateways, bridges, and routers may include TSBs and TPDs to allow for correction for the transit time of time packets through the transfer device. The TPD is normally connected within the media access device at the point of final encoding for transmission or recovery of the clock and data for receiving where the time jitter will be at a minimum.

Abstract: A circuit for an intermediate frequency filter combines a variable bandwidth series resonant filter circuit and a parallel resonant filter circuit. A variable output impedance drives the filter and a variable input impedance amplifier buffers the output of the filter. The output impedance of the driver is made to track the input impedance of the output buffer. Changes in the gain of the filter with respect to bandwidth are relatively small. The noise figure of the filter remains low. The circuit is not operated in the non-linear region of the crystal because relatively low drive currents are needed at narrow bandwidths so that the crystal is not overdriven. The LC filter tunes out the stray capacitance from the load of the crystal filter.

Abstract: A wideband bandpass filter has a tank circuit connected between an input and output tapping circuit. The tank circuit contains a variable capacitor and an inductor in parallel. The tank circuit determines a center frequency for the bandpass filter. The input tapping circuit has an input variable impedance, and the output tapping circuit has an output variable impedance. The input and output variable impedances determine the continuously variable bandwidth of the filter.

Abstract: A laser interferometer measurement system eliminates detection of "false" zero crossings in the measurement signal. The measurement signal is shifted in phase by an integrator or a differentiator. The positive portion of the shifted measurement signal is used to determine falling portions of the measurement signal while the negative portion of the shifted measurement signal is used to determine the rising portions of the measurement signal. Each portion is compared to the reference signal. A SR latch receives the result of each comparator. The output signal of the SR latch reflects the zero crossings of the measurement signal without the effects of noise.

Abstract: An I/O circuit that provides bidirectional signal access to an integrated circuit (IC) core has voltage transformation capability to manage different voltage requirements. Although the I/O circuit and the core are fabricated from the same IC process, the I/O circuit can operate at non-process constrained voltages. The I/O circuit provides an output signal at the necessary voltage level to drive a component in the discrete environment while limiting the voltage supplied to the IC core to the maximum device voltage defined by the selected process.

Abstract: Pin electronics for an IC tester are built as an integrated circuit for testing the electrical operation of a device under test (DUT) by applying a test voltage to each of the pins on the DUT and measuring each resulting current. Typically, when the tester switches between the internal measure resistors, a voltage spike occurs on the pin of the DUT of a magnitude that may severely damage the sensitive circuitry on the DUT. Voltage spike suppression is included in the circuitry to minimize the effects on the DUT of voltage spikes.