A tuning fork sensor system places a controlled bias on the proof-mass drive-axis electrodes to cancel the quadrature charge. Also, its charge amplifiers employ a field-effect transistor biased slightly into the triode region so that it behaves as a very large value resistor. In addition, it uses a phase-locked loop having a special loop filter in order to optimize performance by rejecting off-frequency drive feedthrough to the motor pick-off while resulting in very low phase wander for the demodulation references.

A sensor device includes: first sensors; second sensors generating a mutual capacitance with the first sensors; a sensor transmitter connected to the first sensors, the sensor transmitter supplying driving signals to the first sensors; and a sensor receiver connected to the second sensors. The sensor receiver receives sensing signals from the second sensors. The sensor receiver includes a band pass filter including a plurality of paths connected in parallel. A first path among the plurality of paths sequentially includes an input mixer, a filter, and an output mixer.

A sensor device includes: first sensors; second sensors generating a mutual capacitance with the first sensors; a sensor transmitter connected to the first sensors, the sensor transmitter supplying driving signals to the first sensors; and a sensor receiver connected to the second sensors. The sensor receiver receives sensing signals from the second sensors. The sensor receiver includes a band pass filter including a plurality of paths connected in parallel. A first path among the plurality of paths sequentially includes an input mixer, a filter, and an output mixer.

An analog front-end includes a (1-1)-th charge amplifier configured to differentially amplify a first and second sensing signals provided to a (1-1)-th input terminal and a (1-2)-th input terminal, respectively, and output a (1-1)-th differential signal. A (1-2)-th charge amplifier is configured to differentially amplify the second sensing signal and a third sensing signal provided to a (1-3)-th input terminal and a (1-4)-th input terminal, respectively, and output a (1-2)-th differential signal. A second charge amplifier is configured to differentially amplify the (1-1)-th differential signal and the (1-2)-th differential signal provided to a (2-1)-th input terminal and a (2-2)-th input terminal, respectively, and output a (2-1)-th differential signal and a (2-2)-th differential signal. A demodulation circuit is configured to filter the (2-1)-th differential signal and the (2-2)-th differential signal and output demodulated differential signals. An analog-to-digital converter is configured to output a sensing value based on the demodulated differential signals.

An analog front-end includes a (1-1)-th charge amplifier configured to differentially amplify a first and second sensing signals provided to a (1-1)-th input terminal and a (1-2)-th input terminal, respectively, and output a (1-1)-th differential signal. A (1-2)-th charge amplifier is configured to differentially amplify the second sensing signal and a third sensing signal provided to a (1-3)-th input terminal and a (1-4)-th input terminal, respectively, and output a (1-2)-th differential signal. A second charge amplifier is configured to differentially amplify the (1-1)-th differential signal and the (1-2)-th differential signal provided to a (2-1)-th input terminal and a (2-2)-th input terminal, respectively, and output a (2-1)-th differential signal and a (2-2)-th differential signal. A demodulation circuit is configured to filter the (2-1)-th differential signal and the (2-2)-th differential signal and output demodulated differential signals. An analog-to-digital converter is configured to output a sensing value based on the demodulated differential signals.

A fingerprint capturing apparatus includes a plurality of panel capacitors each configured to output an alternating charge signal indicating a capacitance proportional to a proximity of a portion of a subject's finger, a de-serialized amplifier circuit including an operational amplifier that receives the alternating charge signal from the plurality of panel capacitors, and a change in condition control circuit configured to make a change in an operating condition of the de-serialized amplifier based on a voltage of an output of the operational amplifier. The change in condition control circuit also configured to output a count of a number of times of making the change in the operating condition of the de-serialized amplifier. The apparatus also including a processor circuit configured to recognize the subject's fingerprint based on the count of the number of times of making the change in the operating condition of the de-serialized amplifier.

Correlated double sampling column-level readout of an image sensor pixel (e.g., a CMOS image sensor) may be provided by a charge transfer amplifier that is configured and operated to itself provide for both correlated-double-sampling and amplification of floating diffusion potentials read out from the pixel onto a column bus after reset of the floating diffusion (i) but before transferring photocharge to the floating diffusion (the reset potential) and (ii) after transferring photocharge to the floating diffusion (the transfer potential). A common capacitor of the charge transfer amplifier may sample both the reset potential and the transfer potential such that a change in potential (and corresponding charge change) on the capacitor represents the difference between the transfer potential and reset potential, and the magnitude of this change is amplified by the charge change being transferred between the common capacitor and a second capacitor selectively coupled to the common capacitor.

The present invention increases the output voltage of a switching amplifier in a situation where the power supply voltage is limited. The switching amplifier includes first and second switches that are turned on and off in a complementary manner, and a capacitance, both ends of which serve as inputs to a power combiner. Both ends of the capacitance are connected to output ends of the first and second switches. The capacitance is supplied with power along with the operation of the first and second switches. As a result, an electric charge in the capacitance is used as a charge pump, and is used alternatingly for boosting or stepping down the output voltage depending on the operation frequency of the switching amplifier, thereby generating a rectangular voltage with a controlled wave height.

The present invention increases the output voltage of a switching amplifier in a situation where the power supply voltage is limited. The switching amplifier includes first and second switches that are turned on and off in a complementary manner, and a capacitance, both ends of which serve as inputs to a power combiner. Both ends of the capacitance are connected to output ends of the first and second switches. The capacitance is supplied with power along with the operation of the first and second switches. As a result, an electric charge in the capacitance is used as a charge pump, and is used alternatingly for boosting or stepping down the output voltage depending on the operation frequency of the switching amplifier, thereby generating a rectangular voltage with a controlled wave height.

A sensor device of the present invention includes first sensors receiving a plurality of driving signals; second sensors outputting a plurality of sensing signals in response to the driving signals; and a sensor receiver connected receiving the sensing signals from the second sensors, and including a band pass filter filtering the sensing signals. The band pass filter includes a multi-path filter in which a frequency of the driving signals is set as a center frequency; a gain amplifier amplifying signals filtered through the multi-path filter according to a predetermined gain value; and a buffer isolating the multi-path filter and the gain amplifier from each other.