BACKGROUND

1. Field of the Invention

At least one example embodiment relates to a signal processing circuit for a gyroscope apparatus, and more particularly, to a signal processing circuit for achieving a bandwidth extension and a large loop gain for the gyroscope apparatus.

2. Description of the Related Art

BAW (Bulk Acoustic Wave) MEMS (microelectromechanical system) gyroscope apparatus has a great advantage over a conventional MEMS gyroscope because of its high quality factor (Q) operation in a mode-matched condition. However, the high quality factor gyroscope makes its operation in an open-loop configuration difficult.

Therefore, there is an urgent need to have a signal processing circuit for the gyroscope apparatus with a negative feedback loop, which can extend a rate detection bandwidth and enable the gyroscope apparatus to be not sensitive to a temperature (i.e., making a quality factor of the gyroscope insensitive to the temperature). In other words, there is a need to have the circuit, which could produce a large and stable gain by nulling the Coriolis force sensed.

SUMMARY

According to an aspect, there is provided a signal processing circuit for a gyroscope apparatus. The signal processing circuit for a gyroscope apparatus may include a first electrode and a second electrode pairing with the first electrode. The signal processing circuit may be a negative feedback loop circuit configured to be connected with the first electrode and the second electrode. The signal processing circuit may include a demodulator configured to convert a current from the first electrode into a voltage and demodulate the converted voltage to output a demodulated signal, an analog-to-digital converter configured to convert the demodulated signal from the demodulator into a digital signal, a proportional-integral-derivative controller that is connected to the analog-to-digital converter, a digital-to-analog converter configured to convert an output signal from the proportional-integral-derivative controller to an analog signal, and a modulator configured to be electrically connected with the second electrode and to be electrically connected with the digital-to-analog converter.

The demodulator may include a first transimpedance amplifier, a voltage-to-voltage amplifier, and a first mixer configured to demodulate the converted voltage and outputting to the analog-to-digital converter.

The signal processing circuit may include a first filter configured to reduce a shaped quantization noise of the demodulated signal from the demodulator before outputting to the proportional-integral-derivative controller.

The analog-to-digital converter may be a 1 bit, 3rd-order continuous-time sigma delta modulator.

The digital-to-analog converter may be a 1 bit, 3rd-order digital sigma delta modulator.

The signal processing circuit may include a second filter electrically connecting with the digital-to-analog converter and the modulator. Here, the proportional-integral-derivative controller completely converts the digital signal converted by the analog-to-digital converter to a multi-bit digital data and outputs the multi-bit digital data to the digital-to-analog converter, and the second filter receives the analog signal from the digital-to-analog converter and is configured to reshape the analog signal.

The second filter may filter a quantization noise from the reshaped analog signal.

The second filter may be a 2nd-order switched capacitor filter.

The first filter may be a cascaded integrator-comb filter without a decimator.

The proportional-integral-derivative controller may accurately fix a digital gain based on a quality factor of the gyroscope.

The modulator may include a second transimpedance amplifier, a second mixer, and a voltage-to-current amplifier, and the second mixer may be a pair of switches that are switched with a square-wave rail-to-rail signal.

The proportional-integral-derivative controller may be a digital proportional-integral-derivative controller.

Additional aspects of example embodiments will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the disclosure.

