An apparatus for inductive sensing or capacitive sensing is described. The apparatus may include a signal generator to output on a first terminal a first signal in a first mode and a second signal in a second mode. The apparatus may include a charge measuring circuit to receive on a second terminal a third signal in the first mode and a fourth signal in the second mode. The third signal is representative of an inductance of a sense unit coupled between the first terminal and the second terminal. The fourth signal is representative of a capacitance of the sense unit.

A biological information identification apparatus is provided, including: a fingerprint identification module and a packaging layer disposed on a surface of the fingerprint identification module facing a user, and configured to package the fingerprint identification module to insulate the fingerprint identification module from an outside environment, a top surface of the packaging layer being an arc surface. The fingerprint identification module includes: a fingerprint identification chip configured to identify fingerprint information of the user, where a plurality of capacitive pixel units are disposed on an upper surface of the fingerprint identification chip, and the capacitive pixel units are configured to form capacitance with a finger of the user; and a plurality of conductive elements disposed above the capacitive pixel units. An electronic device including the aforementioned biological information identification apparatus is provided.

Provided are a capacitance detecting circuit, a touch control chip, a touch detection apparatus and an electronic device. The capacitance detecting circuit, by configuring a first input side of an operational amplifier as a preset voltage, and utilizing the same characteristics of voltages at two input sides of the operational amplifier, enables that an output voltage in a touch sensor is configured as a preset voltage by a second input side of the operational amplifier, and by changing a position of a drive of a coding voltage, mutual-capacitance and self-capacitance detection can be realized with the same circuit. After replicating a single-channel current signal output by the operational amplifier into a multi-channel current signal, a current subtracting circuit is used to determine a differential signal of current signals output by two adjacent channels, and the differential signal is converted into a voltage through a charge amplifying circuit.

Systems and methods for determining a touch input are provided. The systems and methods generally include measuring the peak voltage at an electrode over a measurement period and determining a touch input based on the peak voltage. The systems and methods can conserve computing resources by deferring digital signal processing until after a peak electrode capacitance has been sampled. The systems and methods are suitable for capacitive sensors using self-capacitance and capacitive sensors using mutual capacitance. The systems and methods are also suitable for capacitive buttons, track pads, and touch screens, among other implementations.

A sense unit for inductive sensing or capacitive sensing is described. The sense unit may include a first terminal coupled to a first node, a first electrode coupled to the first node, and a second terminal. The sense unit may include a second electrode coupled to the second terminal. In a first mode, a first signal is received at the first terminal and a second signal is output on the second terminal, where the second signal may be representative of a capacitance of the sense unit. The sense unit may include an inductive coil. The sense unit may include a first capacitor. The inductive coil and the first capacitor are coupled in parallel between the first node and ground. In a second mode, a third signal is received at the first terminal and a fourth signal is output on the second terminal.

A system for generating an offset signal for a capacitive sensor includes a waveform generator configured to generate a waveform, an R-2R ladder circuit having a constant output resistance that is coupled to an output of the waveform generator and is configured to generate the offset signal based on the waveform, and an adjustable capacitor that is connected between an output of the R-2R ladder circuit and a reference voltage. The capacitive sensor includes one or more sensing electrodes coupled to the waveform generator through a capacitance and is configured to generate a sensed signal by sensing an object. The R-2R ladder circuit and the adjustable capacitor are configured to adjust amplitude and phase of the offset signal such that the amplitude and the phase of the offset signal respectively coincide with an amplitude and a phase of the sensed signal when the sensing electrodes do not sense the object.

A system for detecting skin contact comprises a signal generator (9) for generating an electric trigger signal; a reference circuit (10) comprising a capacitance (C.sub.REF) and a resistance (RP.sub.REF) for generating a reference signal in dependence on the trigger signal; a probe (11) touchable by a skin for measuring a skin response signal in dependence on the trigger signal; and a comparator (4) for comparing the skin response signal with the reference signal. The capacitance (C.sub.REF) of the reference circuit (10) represents a lower bound of skin capacitance, and the resistance (RP.sub.REF) of the reference circuit represents an upper bound of skin resistance.

A method for operating a capacitive touch-sensitive switch having a capacitive sensor element and a sensor circuit includes initially setting a scanning frequency of the capacitive touch-sensitive switch with a good signal-to-noise ratio and then operating the capacitive touch-sensitive switch at a scanning frequency which has been set to detect switch actuation. The process of setting the scanning frequency includes operating the touch-sensitive switch using a first measurement method and at a selected scanning frequency, detecting the measurement signals from the sensor circuit and checking whether the detected measurement signals contain or could contain a critical alias effect. If no critical alias effect and no possibility of a critical alias effect are detected during the check, the scanning frequency can be set as the selection frequency for detection operation of the touch-sensitive switch. A capacitive touch-sensitive switch is also provided.

A biological information identification apparatus is provided, including: a fingerprint identification module and a packaging layer disposed on a surface of the fingerprint identification module facing a user, and configured to package the fingerprint identification module to insulate the fingerprint identification module from an outside environment, a top surface of the packaging layer being an arc surface. The fingerprint identification module includes: a fingerprint identification chip configured to identify fingerprint information of the user, where a plurality of capacitive pixel units are disposed on an upper surface of the fingerprint identification chip, and the capacitive pixel units are configured to form capacitance with a finger of the user; and a plurality of conductive elements disposed above the capacitive pixel units. An electronic device including the aforementioned biological information identification apparatus is provided.

A high-sensitivity capacitive sensor circuit having improved sensitivity by implementing a plurality of detection units using charging and discharging, has: an oscillation unit for generating a control clock; a first charge/discharge unit connected to a sensing unit electrode, which generates a sensing signal while being charged/discharged according to the control clock; a second charge/discharge unit connected in parallel to the first charge/discharge unit, which generates a reference signal while being charged/discharged according to the control clock; and a detection unit for detecting a change in the capacitance on the side of the sensing unit electrode by comparing the sensing signal from the first charge/discharge unit with the reference signal from the second charge/discharge unit. The first charge/discharge unit includes: a first capacitor connected at one end thereof to the sensing unit electrode, which is charged/discharged according to the control clock; a first constant-current source for supplying a predetermined amount of constant-current to the first capacitor, which charges the first capacitor; and a first switch for controlling the first capacitor such that, according to the control clock, the first capacitor is repetitively charged and discharged every half cycle of the clock. The second charge/discharge unit includes: a second capacitor which is charged/discharged according to the control clock; a second constant-current source for supplying a predetermined amount of constant-current to the second capacitor so as to charge the second capacitor; and a second switch for controlling the second capacitor such that, according to the control clock, the second capacitor is repetitively charged and discharged every half cycle of the clock.