Capacitance detecting sensors and related devices and systems

A capacitance detecting circuit, comprising:

• a pixel sensing circuit that includes a sensing conducting layer that interfaces with an object to form a capacitance with the object;
• a first capacitor coupled to the pixel sensing circuit;
• an integrator electrically coupled to the first capacitor and configured to generate an integrating output voltage, the integrator including:
• a first single-ended amplifier, including:
• an integrating output terminal configured to output the integrating output voltage, and
• a first input terminal coupled to the first capacitor, and
• at least one integration capacitor coupled to the first input terminal;
• and
• a comparator coupled to the integrating output terminal of the first single-ended amplifier and configured to generate a comparing output voltage indicative of the capacitance between the sensing conducting layer and the object;
• wherein the integrator further comprises at least one integrating switching unit coupled between the at least one integration capacitor and the integrating output terminal, and
• wherein the at least one integrating switching unit is coupled to a voltage generator or a ground.

A capacitance detecting circuit, comprising:

• a pixel sensing circuit that includes a sensing conducting layer that interfaces with an object to form a capacitance with the object;
• a first capacitor coupled to the pixel sensing circuit;
• an integrator electrically coupled to the first capacitor and configured to generate an integrating output voltage, the integrator including;
• a first single-ended amplifier, including:
• an integrating output terminal configured to output the integrating output voltage, and
• a first input terminal coupled to the first capacitor, and
• at least one integration capacitor coupled to the first input terminal;
• a comparator coupled to the integrating output terminal of the first single-ended amplifier and configured to generate a comparing output voltage indicative of the capacitance between the sensing conducting layer and the object;
• wherein the integrator further comprises at least one integrating switching unit coupled between the at least one integration capacitor and the integrating output terminal;
• and
• a common mode voltage generator configured to generate a common mode voltage, the common mode voltage generator comprising:
• a second single-ended amplifier comprising:
• a second input terminal;
• and
• a second output terminal coupled to be a part of the at least one integrating switching unit and the second input terminal via a connecting switch;
• and
• a plurality of common mode capacitors coupled to the second input terminal.

A fingerprint identification system, comprising:

• a plurality of pixel sensing circuits at different locations to interface with a finger to capture at least a portion of a fingerprint of the finger;
• a capacitance detecting circuit coupled to the plurality of pixel sensing circuits and configured to generate a plurality of capacitance outputs corresponding to the plurality of pixel sensing circuits, the capacitance detecting circuit comprising:
• a first capacitor;
• an integrator configured to generate an integrating output voltage, comprising:
• a first single-ended amplifier, comprising:
• an integrating output terminal configured to output the integrating output voltage;
• and
• a first input terminal coupled to the first capacitor;
• and
• at least one integration capacitor coupled to the first input terminal;
• a second capacitor;
• a comparator configured to generate a comparing output, the comparator comprising:
• a negative input terminal coupled to the integrating output terminal of the first single-ended amplifier;
• a positive input terminal configured to receive a reference voltage;
• and
• a comparing output terminal configured to output the comparing output;
• and
• a counter coupled to the comparing output terminal and configured to generate a plurality of counter outputs corresponding to the plurality of pixel sensing circuits as the plurality of capacitance outputs;
• and
• a fingerprint determining module coupled to the capacitance detecting circuit and configured to determine a location of each pixel sensing circuit corresponding to a finger ridge or a finger valley based on the corresponding capacitance output;
• wherein a connection between the second capacitor and the first input terminal is controlled to be turned ON or OFF based on the comparing output.

A capacitance detecting circuit, comprising:

• a first capacitor, comprising a first end coupled to a pixel sensing circuit and a second end;
• an integrator;
• a first switch coupled between the first end of the first capacitor and a ground;
• a second switch coupled between the second end of the first capacitor and the integrator;
• and
• a conducting layer coupled to the voltage generator via a fifth switch and the first capacitor via a sixth switch.

A capacitance detecting circuit, comprising:

• a pixel sensing circuit that interfaces with an object to form a capacitance with the object;
• a first capacitor, coupled to the pixel sensing circuit;
• an integrator electrically coupled to the first capacitor and configured to generate an integrating output voltage, the integrator including:
• a first single-ended amplifier, including:
• an integrating output terminal configured to output the integrating output voltage, and
• a first input terminal coupled to the first capacitor, and
• at least one integration capacitor coupled to the first input terminal;
• an array of capacitors, one terminal of each capacitor in the array being switched to a predetermined voltage or switched open;
• and
• a comparator coupled to the integrating output terminal of the first single-ended amplifier and configured to generate a comparing output voltage indicative of the capacitance between the pixel sensing circuit and the object.