A monolithic surface micromachined Z-axis vibratory rate gyroscope with an on-chip A/D converter is fabricated in a monolithic MEMS/circuits technology with 2μm CMOS and 2.25μm-thick mechanical polysilicon. The on-chip position sense circuit uses correlated double sampling to reject 1/f and kT/C noise and resolves 0.02Angstrom displacements. The gyroscope achieves a noise floor of 3°/sec/√Hz at atmospheric pressure and operates from a single 5V supply.

Abstract—A proposed third-order noise-shaping accelerometer interface circuit enhances the signal-to-noise ratio, compared with previously presented interface circuits. The solution for the two-chip implementation is described and a novel cross-coupled correlated double sampling integrator is proposed. This scheme functions even with large parasitic capacitances between the sensor and the interface circuit. The op-amp noise is first-order shaped. Dithering circuit is also implemented on the chip, fabricated in an 1.6- m CMOS process. Index Terms—Accelerometer, correlated double sampling (CDS), delta–sigma modulator, dither, sensor interface. I.

A capacitive position measurement interface minimizes noise from parasitics in the electromechanical interface and uses correlated double sampling to achieve better than 10-3 Å/√Hz displacement resolution. This translates into 2µG/√Hz acceleration resolution when the device is operated in a vacuum.

This paper introduces a new architecture for sensor interface circuits using a delta-sigma modulator. The three-level force feedback allows the use of a digital compensator to stabilize the loop. A 3rd-order delta-sigma structure shapes the opamp noise and allows two-chip implementation with high loop gain at low frequencies. 1.

Abstract—Nowadays, 61-modulation is a widely used technique for analog-to-digital (A/D) conversion, especially when aiming for high resolutions. While being applied initially for purely electrical A/D converters, its application has been expanded to mixed mechanical–electrical systems. This has led to the use of 61 force-feedback for digital readout of high-performance inertial sensors. However, compared with their electrical counterpoint, 61 force-feedback loops often have to deal with three additional issues: 1) an increased stability problem due to phase-lag occurring in the sensor; 2) the injection of relatively high levels of readout noise in the loop; and 3) the lack of degrees-of-freedom of many 61 force-feedback architectures for implementing an arbitrary noise transfer function. As a result, 61 force-feedback loops found in literature are designed in a much less systematic way as compared with electrical 61 modulators. In this paper, we address these issues and propose a new unconstrained architecture. Based on this architecture, we are able to present a systematic approach for designing 61 force-feedback loops. Additionally, the main strengths and weaknesses of different 61 force-feedback architectures are discussed. Index Terms—A/D-conversion, force-feedback, MEMS inertial sensors, sigma-delta (61) modulation, systematic design.

Thumbnail-sized inertial measurement systems based on Micro Electro Mechanical Systems (MEMS) technology have been perceived as a breakthrough in the field of inertial navigation. However, even as micromechanical accelerometers have seen widespread commercialization, vibratory micromechanical gyroscopes have not enjoyed similar success. Previous approaches to high-performance micromechanical gyroscope design have been complicated by two factors: first, the requirement for precise control of the trajectory of a multi-degree of freedom vibrating micromechanical structure, and second, the development of calibration schemes that must precisely identify system parameters that are often sensitive functions of ambient environmental variables. This thesis describes a new angular rate sensor, termed the “Resonant Output Gyroscope”, that considerably simplifies both the control system and the calibration procedure. In its simplest form the device comprises of three coupled micromechanical oscillators. Two of these oscillators sense the Coriolis force acting upon a third vibrating mass (in response to an input rotation rate) as a shift in their operating frequency. Detection of this frequency shift results in an2 estimate of the input angular motion. A prototype device fabricated at the Sandia National