Seoul National University

Gwanak Analog Co., Ltd.

Minsung Kim

Suhwan Kim

Jaehoon Jun

Hyunjoong Lee

A read-out circuit includes an operational amplifier configured to receive input voltage via a positive input terminal; a feedback capacitor connected between an output terminal of the operational amplifier and a negative input terminal of the operational amplifier; a sensor charging/discharging circuit configured to charge or to discharge a sensor capacitor included in a sensor during a first time; and a switching circuit configured to connect the sensor capacitor and the operational amplifier during a second time after the sensor capacitor is charged or discharged.

Read-out circuit for a capacitive sensor

A read-out circuit includes an operational amplifier configured to receive an input voltage through a positive input terminal; a feedback capacitor connected between an output terminal of the operational amplifier and a negative input terminal of the operational amplifier; a sensor charging and discharging circuit configured to charge or discharge a sensor during a first time; a switching circuit connecting the sensor and the operational amplifier during a second time after the sensor is charged or discharged; and a duty control circuit configured to determine a duty ratio of the first time and the second time according to a capacitance of the sensor.

A delta-sigma modulator generates a bit stream signal from an analog signal by operating according to a modulation period including a sampling period and a filtering period and includes a digital-to-analog converter (DAC) configured to generate a charge signal according to one of a first reference voltage and a second reference voltage according to the bit stream signal during the sampling period and to output a signal generated according to the charge signal and the other of the first reference voltage and the second reference voltage; a loop filter configured to charge a sampling signal corresponding to the analog signal during the sampling period and to filter an output from the DAC and a signal generated according to the sampling signal during the filtering period; and a quantizer configured to generate the bit stream signal according to an output from the loop filter in the modulation period.

Delta-sigma modulator and analog-to-digital converter including the same

An analog-to-digital converter (ADC) includes an input circuit configured to receive a first analog signal output from a first sensor or a second analog signal output from a second sensor according to an operation mode and a bit stream; a filter configured to filter an output signal from the input circuit; a quantization circuit configured to generate the bit stream from an output signal of the filter; and a digital circuit configured to generate a first digital signal corresponding to the first analog signal or a second digital signal corresponding to the second analog signal by filtering the bit stream, wherein the operation mode includes a first mode selecting the first sensor and a second mode selecting the second sensor, and wherein the digital circuit refers to the second digital signal generated during the second mode to generate the first digital signal during the first mode.

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Gwacheon-si, South Korea

Minsung Kim