Schlumberger Industries

Sangamo Weston, Inc.

Robert A Leydier

Joseph Goss

Vincent Mosser

Ian Suski

The pressure sensor is formed of semiconductor material which is formed on insulating support, i.e., as a semiconductor-on-silicon. The sensor is comprised of four piezoresistive gauges formed in the semiconductor material. Two of the gauges, each have a pair of limbs joined by a base, such that they are U-shaped, and two others are I-shaped. Each of the four gauges comprise two half-gauges, and each half-gauge comprises an elongated sensing zone in semiconductor material and having a reduced width in the plane of the insulating support. Two ohmic contact zones are disposed at the ends of each of the half-gauges, and two connection zones in semiconductor material and of greater width are disposed between the sensing zones and the ohmic contact zones, the form of the two connection zones are the same for each of the eight half-gauges.

Semiconductor pressure sensor

A triangle waveform generator for a pulse-width amplitude multiplier includes a digital-to-analog converter and a charge transfer network. Clocked signals applied to the converter, which includes a resistor chain for providing a set of different potentials, sequentially select ones of the potentials and supply two of them to the charge transfer network. The network weights each of the potentials received, then combines them at an output node. By employing appropriate clocking of the converter, a triangular waveform having a plurality of discrete steps results.

Triangle waveform generator for pulse-width amplitude multiplier

A high accuracy power meter capable of measuring power supplied or consumed in multiple phases of a distribution system is fabricated as an integrated circuit. Voltage and current sensing transducers coupled to the power meter provide input signals having a potential proportional to the voltage and current in the distribution system. A low charge injection pulse width amplitude multiplier using a digitally-synthesized triangular wave is provided for each phase. Each multiplier receives the input signals and provides an output signal having a current proportional to the product of voltage and current in that phase of the distribution system. Charge from the multiplier output currents for all phases is accumulated in a capacitor connected across an autozeroing amplifier, which corrects for its own offset voltage. The amplifier output controls a switch connected between a reference potential and the capacitor. When the switch is closed, a reference current is supplied to the accumulating capacitor to balance the charge from the multiplier for each phase. The frequency of the switch control signal provides a highly accurate measure of the power consumed or supplied by the distribution system.

Integrated poly-phase power meter

An autozeroing operational amplifier for a voltage or current-to-frequency converter includes a master amplifier and a slave amplifier. The master amplifier uses the voltage across a master capacitor to control the polarization level of an MOS transistor. Changing this level changes the operation of a differential pair connected to a load thereby changing the amplifier's input offset voltage. The slave amplifier, similarly constructed, is connected to periodically refresh the voltage across the master capacitor to compensate for drift and temperature effects.

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Mountain View, CA, United States of America

Robert A Leydier