Actel Corporation, Inc.

Bei Technologies, Inc.

Bei Sensors & Systems Company, Inc.

G Richard Newell

Michael R Layton

Larry P Hobbs

Timothy R Hilby

A circuit and method for compensating sigma-delta modulators in A/D and D/A converters is disclosed. Circuits according to the invention use a low-resolution Sigma-Delta encoded version of the signal to inexpensively encode quadratic and cubic compensation terms. These circuits can encode quadratic and cubic compensation signals with acceptably low quantization noise without requiring the use of expensive multi-bit multipliers to compute the square or cube of the signal. The method includes providing a binary word Q or a binary word C (or both) representing the desired amount of quadratic or cubic compensation to apply. Because the encoded quadratic and cubic signals have only one or a few bits, they can be multiplied by Q and C without the use of expensive multi-bit multipliers and applied to the modulator input or output to provide a compensated result.

Quadratic and cubic compensation of sigma-delta D/A and A/D converters

Inertial rate sensor and method in which a drive signal is applied to a rate sensing element, a pickup circuit is coupled to the rate sensing element for providing an output signal corresponding to movement of the rate sensing element, digital logic calibrates the rate sensor and detects the occurrence of faults in the rate sensor, the rate sensing element is utilized as a frequency reference for providing a system clock signal for the digital logic, a fixed phase relationship is maintained between vibration of the rate sensing element and the system clock signal, the system clock signal is filtered to eliminate responses to spurious transitions during a period following application of operating power to the sensor, and the digital logic is reset in synchronization with the system clock signal.

Inertial rate sensor and method with improved clocking

A closed loop sensor that utilizes a piezoelectric structure. In one embodiment, drive/non-control electrodes apply drive voltages to the piezoelectric structure and drive/control electrodes apply drive/control voltages to the piezoelectric structure to cause drive mode displacement of the piezoelectric structure and cancel motion induced pickup mode and quadrature displacements of the piezoelectric structure. In another embodiment, pickup/control electrodes detect a pickup signal from the piezoelectric structure corresponding to the motion induced pickup mode and quadrature displacements and apply a control signal to the piezoelectric structure so as to cancel these displacements. In still another embodiment of the invention, an optical sensing device optically senses the motion induced pickup mode and quadrature displacements and control electrodes apply a control signal to the piezoelectric structure so as to cancel them.

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Walnut Creek, CA, United States of America

G Richard Newell