Abstract: This document discusses, among other things, apparatus and methods for digital automatic gain control for driving a MEMS device, such as a proof mass. In an example, an apparatus can include a driver configured to oscillate a proof mass of a MEMS device, a charge-to-voltage (C2V) converter configured to provide oscillation information of the proof mass, an analog-to-digital converter (ADC) configured to provide a digital representation of the oscillation information, and a digital, automatic gain control circuit to provide oscillation amplitude error information using a comparison of the oscillation information to target amplitude information, and to provide a digital drive command signal using an amplified representation of the oscillation amplitude error information.

Abstract: A contact lens, system of contact lenses, and a method for detecting eye convergence includes detecting a first inward gaze with first gaze detection circuitry included in a first contact lens disposed on a first eye. A first inward gaze signal is transmitted from the first contact lens to a second contact lens disposed in a second eye in response to detecting the first inward gaze. A second inward gaze is detected with second gaze detection circuitry included in a second contact lens disposed on the second eye. The first inward gaze signal is received by the second contact lens. If the first inward gaze signal is received within a pre-determined time period from detecting the second inward gaze, an optical power for the second eye is adjusted.

Abstract: A contact lens for lens-to-lens communication includes blink detection circuitry, one or more electrodes, a logic engine, and data transmission circuitry. The blink detection circuitry is configured to generate a blink signal in response to a blinking of an eye. The logic engine is coupled to receive the blink signal from the blink detection circuitry. The data transmission circuitry is coupled between the one or more electrodes and the logic engine. The logic engine causes the data transmission circuitry to drive electrical data signals onto the one or more electrodes in response to the blink signal reaching a pre-determined threshold.

Abstract: The temperature-dependent resistance of a MEMS structure is compared with an effective resistance of a switched CMOS capacitive element to implement a high performance temperature sensor.

Abstract: This document discusses, among other things, apparatus and methods for a front-end charge amplifier. In certain examples, a front-end charge amplifier for a microelectromechanical system (MEMS) device can include a charge amplifier configured to couple to the MEMS device and to provide sense information of a proof mass of the MEMS device, a feedback circuit configured to receive the sense information and to provide feedback to an input of the charge amplifier, and wherein the charge amplifier includes a transfer function having a first pole at a first frequency, a second pole at a second frequency, and one zero at a third frequency.

Abstract: This application discusses, among other things, simplified interface circuits for a gyroscope. In an example, a interface can include an automatic gain control (AGC) circuit configured to couple to driver for a proof mass of a gyroscope sensor and to drive the proof-mass to oscillate at a predefined oscillation amplitude, and a phase-locked loop (PLL) configured to receive sensed oscillation information from the proof-mass and to provide at least a first phase signal synchronized with a sinusoidal waveform of the sensed oscillation information.

Abstract: An embodiment of an eye-mountable device includes an optical lens; an accommodation actuator to provide vision accommodation for the optical lens; a controller including an accommodation logic to select one of a plurality of vision accommodation states for the device, the plurality of vision accommodation states including at least a failsafe focal distance; and a failsafe subsystem including a system health detector, the system health detector to monitor for one or more operational indicators for the device, wherein the failsafe subsystem is to cause the device to transition to a failsafe mode upon the failsafe subsystem identifying a failure condition for the device, the failsafe mode includes setting the vision accommodation state to be the failsafe focal distance.

Abstract: A temperature to digital converter circuitry to generate output data which is representative of one or more temperature dependent characteristics of a temperature sensitive device (for example, MEMS thermistor having a resistance that correlates to its temperature), the temperature to digital circuitry comprising a switched capacitor network to generate a effective reference resistance in response to a switching signal, a signal generator to generate the switching signal, wherein the switching signal has a switching frequency which is controlled, at least in part, via control data, comparator circuitry to generate error data using the effective reference resistance and the resistance of the temperature sensitive device, and converter circuitry to generate the output data which is representative of one or more temperature dependent characteristics of the temperature sensitive device.

Abstract: This document discusses, among other things, a temperature and power supply calibration system configured to compensate for temperature and supply voltage variation in MEMS or other circuits using representations of positive and negative supply voltages and first and second base-emitter voltages, wherein the second base-emitter voltage is a scaled representation of the first base-emitter voltage.

Abstract: An apparatus includes a drive signal circuit for MEMS sensor. The drive signal circuit includes an input configured to receive a voltage signal representative of charge generated by the MEMS sensor, a phase-shift circuit electrically coupled to the input and configured to phase shift an input signal by substantially ninety degrees, and a comparator circuit with hysteresis. An input of the comparator is electrically coupled to an output of the phase-shift circuit and an output of the comparator circuit is electrically coupled to an output of the drive signal circuit. A feedback loop extends from the output of the drive signal circuit to the input of the phase-shift circuit and is configured to generate a self-oscillating signal at an output of the drive signal circuit. An output signal generated by the drive signal circuit is applied to a drive input of the MEMS sensor.

Abstract: This document discusses, among other things, apparatus and methods quadrature cancelation of sense information from a micro-electromechanical system (MEMS) device, such as a MEMS gyroscope. In certain examples, a quadrature correction apparatus can include a drive charge-to-voltage (C2V) converter configured to provide drive information of a proof mass of a MEMS gyroscope, a sense C2V converter configured to provide sense information of the proof mass, a phase-shift module configured to provide phase shift information of the drive information, a drive demodulator configured to receive the drive information and the phase shift information and to provide demodulated drive information, a sense demodulator configured to receive the sense information and the phase shift information and to provide demodulated sense information, and wherein the quadrature correction apparatus is configured to provide corrected sense information using the demodulated drive information and the demodulated sense information.

Abstract: This document discusses, among other things, apparatus and methods for digital automatic gain control for driving a MEMS device, such as a proof mass. In an example, an apparatus can include a driver configured to oscillate a proof mass of a MEMS device, a charge-to-voltage (C2V) converter configured to provide oscillation information of the proof mass, an analog-to-digital converter (ADC) configured to provide a digital representation of the oscillation information, and a digital, automatic gain control circuit to provide oscillation amplitude error information using a comparison of the oscillation information to target amplitude information, and to provide a digital drive command signal using an amplified representation of the oscillation amplitude error information.

Abstract: This document discusses, among other things, apparatus and methods for a front-end charge amplifier. In certain examples, a front-end charge amplifier for a microelectromechanical system (MEMS) device can include a charge amplifier configured to couple to the MEMS device and to provide sense information of a proof mass of the MEMS device, a feedback circuit configured to receive the sense information and to provide feedback to an input of the charge amplifier, and wherein the charge amplifier includes a transfer function having a first pole at a first frequency, a second pole at a second frequency, and one zero at a third frequency.

Abstract: An apparatus includes a drive signal circuit for MEMS sensor. The drive signal circuit includes an input configured to receive a voltage signal representative of charge generated by the MEMS sensor, a phase-shift circuit electrically coupled to the input and configured to phase shift an input signal by substantially ninety degrees, and a comparator circuit with hysteresis. An input of the comparator is electrically coupled to an output of the phase-shift circuit and an output of the comparator circuit is electrically coupled to an output of the drive signal circuit. A feedback loop extends from the output of the drive signal circuit to the input of the phase-shift circuit and is configured to generate a self-oscillating signal at an output of the drive signal circuit. An output signal generated by the drive signal circuit is applied to a drive input of the MEMS sensor.