Massachusetts Institute of Technology

Microsensors Corp.

Aetna Telecommunications Laboratories

James K Roberge

Martha L Gray

John S Piso

John O Silvey

John E Ward

A technique for measuring capacitance and displacement, in which two circuits are combined, one that produces a current proportional to capacitance, and another that integrates that current between two reference levels, and supplies an output proportional to the integration time. In preferred embodiments, the first circuit is a capacitive pump circuit, and the second circuit a dual-slope integrator.

Method for the measurment of capacitance, with application to linear

A diode driver circuit has an adjustable, fixed-value current source and a variable offset current source for drawing a bias current through a laser diode. A Darlington pair buffer circuit isolates the diode from the rest of the driver circuit. The output current of the offset current source is controlled by a number of digital-to-analog converters each controlling a different contribution to the total offset current. A diode protector circuit protects the diode when the system is in an inactive state.

Diode driver circuit utilizing discrete-value DC current source

A temperature controller for a thermal system comprises a linearized feedback loop. A linearized thermistor and heating element are disclosed. A current source adjusts the bias current of the thermistor so that the thermistor voltage is equal to a given voltage when the thermistor is at the desired temperature. When the thermistor is biased in this way, the incremental gain from temperature errors to thermistor voltage errors becomes independent of set point. The heating element includes a power regulator and a power resistor. Because temperature is a linearly related to the power dissipated in the power resistor, square-law circuitry keeps the voltage output of the power regulator linearly related to the square root of the error in the controlled temperature. In other embodiments of the invention, a voltage source adjusts the bias voltage of the thermistor so that the incremental gain from temperature errors to thermistor current errors is independent of set point.

Linearized thermal feedback circuit and temperature controller circuit

A fast settling amplifier for use in a phase locking system operative to phase lock a local clock to incoming data bits in a packet of short duration within a specified accuracy range, using no more than a few initial bits of the packet. Phase locking is achieved by phase shifting the data packet bits relative to a local clock signal a fixed, non-integral fraction of a bit period until the phasing lies within the specified range. The phasing is then accurate enough to permit signal decoding with an open loop over the limited duration of the packet. The phase locking process is activated each time the beginning of a new packet is detected. A Manchester code is typically utilized as the representation of the signal upon which synchronization is achieved. The Manchester code or biphase signal is recovered from the telecommunications network by a fast settling amplifier that rapidly establishes thresholding to accurately distinguish between high and low level signal levels in the Manchester code while maintaining a well filtered signal level.

Real time network receiver system fast settling amplifier

The amount of electrically conductive finish that has been applied to a filament is determined by measuring the conductance of a length of the filament. The measurements are made independently of any difference in conductivity of finish mediums by means of a reference cell containing a sample of the particular finish medium used. An electric measurement circuit provides an indication of the amount of finish medium on the filament by determining the ratio of the conductance of the length of filament to the conductance of the reference cell. In one circuit embodiment, two operational amplifiers are placed in series. The reference cell takes the place of the feedback resistor of one operational amplifier and the length of filament takes the place of the input resistance of the other amplifier. The resulting output of the series circuit is a scaled ratio of the conductances of the finish along the length of filament and in the cell. In another circuit embodiment, voltages applied through the length of filament and reference cell are selectively switched into a dual slope integrating circuit. In its preferred form, the finish measuring apparatus is a hand-held device having contacts which may be connected to a filament using a trigger mechanism.

Finish measuring method and apparatus

An optical torquemeter adapted to provide torque readings as accurate as 1-to-2 foot pounds over a torque range of the order of 1 to 2 thousand foot pounds. It converts a binary-type optical message to an electric signal in the form of variable-width pulses. The width of the electric pulses indicates both the magnitude and the direction of torque and the pulses are processed to provide an output representing torque.

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Lexington, MA, United States of America

James K Roberge