Abstract: A stable and accurate level shifter for converting voltage levels of signals in CMOS devices. In one embodiment of the invention, the level shifter comprises two legs having transistors operably connected in a source-follower configuration. The biasing of the level shifter is provided by a multistage biasing circuit that comprises a plurality of N-MOS devices. The biasing source can be operated with a single stage or can be configured to combine multiple stages to increase the current (voltage) provided by the biasing circuit. The level shifter of the present invention consumes less power and requires less area on an integrated circuit than prior art level shifters. In addition, the level shifter is insensitive to negative bias temperature instability (NBTI) effects, thereby allowing the level shifter to be highly reliable throughout the life of the part with minimal degradation in the performance and accuracy of the level shifter through time.

Abstract: A method and apparatus for decreasing crosstalk between conductors, particularly differential pairs, that are routed in high-density patterns on printed circuit boards system. In one embodiment of the invention, a single-ended conductor is divided at a first point into two single-ended conductors of equal width, with the two single-ended conductors being routed around and alongside a differential pair of conductors. Equal and opposite noise is coupled onto each branch of the single-ended signal from each side of the differential pair. The two single-ended conductors are rejoined at a second point to form a combined single-ended conductor. Signals traveling along the two separate paths of the single-ended are combined at the second point and noise carried in the respective signals is cancelled. Noise coupled into the differential pair from the two single-ended paths is eliminated at the receiving end as common mode noise.

Abstract: An inflation system for providing rapid, linear inflation of a container, such as an occlusion cuff used in connection with a blood pressure monitoring system. The invention system provides an automatic fast-fill of the cuff to a predetermined pressure level, followed by a smooth, linear pressurization profile which is independent of the volume of the cuff. An efficient electronic actuation system allows the system to inflate the cuff many times using the power supplied by a low power battery. A pressure relief system is provided to automatically terminate operation of the inflation system once systolic pressure has been detected or if the pressure in the system rises above a predetermined level. The system is extremely lightweight and compact, thus allowing a patient to carry the system on his person without undue fatigue.

Abstract: A method and apparatus for providing optimum control of a refrigeration system during both its cooling cycle and its defrost cycle. During the cooling cycle, the control system maintains operation of a fan for a predetermined period of time sufficient to fully evaporate the liquid refrigerant in the refrigeration system's evaporator coil. The control system initiates the defrost cycle only when the actual system parameters indicate the need to defrost. In the defrost cycle, the flow of hot gas and refrigerant is coordinated in a manner to minimize the amount of energy expended and to reduce thermal shock to the system, thereby eliminating unnecessary wear on the system components.

Abstract: An electronically actuated switching valve for controlling the flow of gas streams in a pneumatic system. The preferred embodiment of the invention comprises a double piloted three-way spool valve which moves within a valve housing having a plurality of ports which cooperate with the spool valve to direct gas streams in a predtermined manner. The position of the valve spool within the housing is controlled by pressure pilots on either side of the valve spool. Electronically actuated solenoid exhaust valves are operable to cause pressure drops in the pressure pilots to cause the valve spool to change position. Once the valve spool has changed position, it is maintained in that position without the need for a continuous supply of electric current to the electronic actuators.

Abstract: A noninvasive optical oximeter for measuring oxygen saturation of arterial blood. A sample of blood is illuminated with light at two different wavelengths. Light reflected by the blood is sensed by a photodetector and an output signal is created in response thereto. The output signal is processed to form a quotient representing the AC components of the reflected light at each wavelength. The oxygen saturation of the blood is calculated by correlating this quotient with an oxygen saturation reference curve uniquely representative of the blood oxygen saturation characteristics of a particular individual.

Abstract: A ball return device for aiding in the practice of basketball or other games which require that a ball be returned to a player in order to perform repetitive practice routines. The device comprises a receiving basket which may be placed under a basketball hoop and which directs a ball to a pair of rotating heads operable to propel the ball toward the player. A detection apparatus on the return device is operable to sense the distance between a player and the return device. When the distance between the player and the return device is within a zone of acceptable distances, an output signal is generated which causes the return mechanism to eject a ball toward the player.

Abstract: A method and apparatus for efficiently coupling a transceiver to an AC power line transmission system. The preferred embodiment of the coupling system comprises a line coupling network and first and second filter ports. The first filter port is connected to a resonant circuit having bandpass filtering characteristics adapted to the specific needs of the transmitter portion of the transceiver. The second filter port is isolated from the low impedance of the AC power line and is connected to a high quality factor filter having bandpass filtering characteristics adapted to the specific needs of the receiver portion of the transceiver.