Invensense, Inc.

Maxim Integrated Products, Inc.

Panasonic Corporation

Federico Mazzarella

Massimiliano Musazzi

Luca Coronato

Giacomo Gafforelli

Adolfo Giambastiani

Michele Folz

Carlo Pinna

Vito Avantaggiati

Marco Masini

Luca Collamati

Musazzi Massimiliano

A capacitive sensing charge amplifier, e.g., in a direct current (DC) feedback network, may incorporate a switching capacitor, including a first control switch and a second control switch, which receives a switching signal to charge and discharges the switching signal to a virtual ground of a sense amplifier. Noise incorporated into the output of the sense amplifier (e.g., a MEMS output signal) is filtered by a demodulation signal at a demodulator such that the period average noise at the demodulator output equals zero. The time varying nature of the switching capacitor resistance generally reshapes the system's post-demodulation noise to reduce its low frequency output noise.

DC restore scheme for capacitive sensing amplifiers with optimal noise filtering

In a microelectromechanical system (MEMS) sensor, movement of a component such as a proof mass due to a force of interest is sensed capacitively. A capacitance-to-voltage (C2V) converter receives a capacitance signal from the sensor and outputs a signal that includes an offset in addition to a signal of interest. The output signal is analyzed to identify the offset portion of the output signal and to modify values one or more variable capacitors coupled to the C2V input reduce the offset portion of the output signal.

Dynamic capacitance-to-volvage offset cancellation

An algorithm and architecture for sense transfer function estimation injects one or more test signals from a signal generator into a MEMS gyroscope to detect an output signal (e.g., proof mass output sense signal), including an in-phase (e.g., Coriolis) component and a quadrature component. The in-phase and quadrature components are encoded with reference signals to determine phase and/or gain variation and are processed via a variety of components (e.g., matrix rotation, digital gain, tones demodulator, transfer function errors estimation, etc.) to estimate a sense transfer function of the MEMS (e.g., H(f)) and corresponding phase and/or gain offset of H(f). The in-phase and quadrature components are also compensated for phase and/or gain offset by system components.

4-points phase and sensitivity estimation algorithm and related architecture

The described technology is generally directed towards a sensor output digitizer. The sensor output digitizer can comprise a multiplexer stage, a multi-stage analog to digital converter, and a digital output combiner. The multiplexer stage can be configured to sequentially select sensor outputs from one or more sensors, resulting in a stream of selected sensor outputs. The multi-stage analog to digital converter can be coupled with the multiplexer stage, and can be configured to convert the stream of selected sensor outputs into a stream of digitized outputs. The digital output combiner can be configured to re-scale and sum intermediate outputs of the multi-stage analog to digital converter to produce a stream of digitized sensor outputs.

Sensor output digitizer

A microelectromechanical (MEMS) accelerometer has a proof mass, a sense electrode, and an auxiliary electrode. The sense electrode is located relative to the proof mass such that a capacitance formed by the sense electrode and the proof mass changes in response to a linear acceleration along a sense axis of the accelerometer. The auxiliary electrode is located relative to the proof mass such that a capacitance formed by the auxiliary electrode and proof mass is static in response to the linear acceleration. A sense drive signal is applied at the sense electrode and an auxiliary drive signal is applied at the auxiliary electrode. The sense drive signal and the auxiliary drive signal have different frequencies. An error is identified based on a portion of a signal that is received from the accelerometer and that is responsive to the auxiliary drive signal. Compensation is performed at the accelerometer based on the identified error.

Identification and compensation of MEMS accelerometer errors

Various embodiments of the invention provide for a buck-boost circuit that is immune against being stuck in an undesirable mode of operation. The circuit does not require any additional intermediate states other than buck-mode and boost-mode when managing transitions between buck and boost mode. In certain embodiments, a robust and simple buck-boost topology ensures efficient and rapid transitions by operating comparators that are coupled to switching elements of the buck-boost in such a manner that the inductor current can be selectively monitored to detect an inductor current slope during a power transfer phase. Information about the current slope enables a controller to make a decision whether a transition to another state is appropriate.

High efficiency buck-boost systems and methods

A microelectromechanical (MEMS) accelerometer has a proof mass, a sense electrode, and an auxiliary electrode. The sense electrode is located relative to the proof mass such that a capacitance formed by the sense electrode and the proof mass changes in response to a linear acceleration along a sense axis of the accelerometer. The auxiliary electrode is located relative to the proof mass such that a capacitance formed by the auxiliary electrode and proof mass is static in response to the linear acceleration. A sense drive signal is applied at the sense electrode and an auxiliary drive signal is applied at the auxiliary electrode. The sense drive signal and the auxiliary drive signal have difference frequencies. A portion of a sensed signal at the sense drive frequency is used to determine linear acceleration while a portion of the sensed signal at the auxiliary drive frequency is used to identify damage within a sense path from the proof mass.

Accelerometer sense path self-test

An accelerometer has a plurality of proof masses and a plurality of sense electrodes, which collectively form at least two capacitors. A first sense drive signal is applied to a first capacitor and a second sense drive signal is applied to a second capacitor. Both of the sense drive signals have the same sense drive frequency. Capacitance signals are sensed from each of the first capacitor and second capacitor, and a common mode component of the capacitance signals is determined. A capacitor error is identified based on the common mode component.

Accelerometer common mode self-test

A system and method for making accurate current measurements by determining the differential voltage drop across a resistor in series with the load in the presence of large common mode voltages. A compensating voltage equal in magnitude but 180 degrees out of phase with a common mode voltage is generated and applied to a network of resistors connected to a measurement amplifier, thereby significantly reducing the magnitude of the common mode voltage at the measurement amplifier's inputs. An error correction voltage is generated and applied to the output of the measurement amplifier to compensate for errors in the values of the resistor network.

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Binasco, Italy

Federico Mazzarella