To provide a hysteresis comparator having a small circuit area and low power consumption. The hysteresis comparator includes a comparator, a switch, a first capacitor, a second capacitor, and a logic circuit. A first terminal of the switch is electrically connected to one of a pair of conductive regions of the first capacitor, one of a pair of conductive regions of the second capacitor, and a first input terminal of the comparator. An output terminal of the comparator is electrically connected to an input terminal of the logic circuit. An output terminal of the logic circuit is electrically connected to the other of the pair of conductive regions of the second capacitor. The logic circuit has a function of generating an inverted signal of a signal input to the input terminal of the logic circuit and outputting the inverted signal to the output terminal of the logic circuit. A reference potential is input to the first input terminal of the comparator and the reference potential is held by the switch. Due to change in the potential of the output terminal of the comparator, the reference potential is changed by capacitive coupling of the second capacitor.

Disclosed is a transmitter which includes a channel driver that includes a pull-up transistor and a pull-down transistor connected between a power node and a ground node and outputs a voltage between the pull-up transistor and the pull-down transistor as a transmit signal, and a pre-driver that controls the pull-up transistor and the pull-down transistor in response to a driving signal and controls the channel driver such that the transmit signal is overshot at a rising edge of the driving signal and the transmit signal is undershot at a falling edge of the driving signal.

A transmitter includes a driving circuitry configured to drive a channel coupled to an output node by controlling an output impedance of a pull-up path, an output impedance of a pull-down path, or both, according to one or more multi-bit data signals, a pull-up control signal, and a pull-down control signal; a driving control circuit configured to generate the pull-up control signal and the pull-down control signal according to one or more calibration signals and the multi-bit data signals or according to the calibration signals and one or more duplicate multi-bit data signals, the duplicate multi-bit data signals duplicating the multi-bit data signals; and a look-up table storing values of the calibration signals.

A driver system may include a first n-type field-effect transistor coupled at its non-gate terminals between an output of the driver system and a first terminal of a supply voltage and configured to drive the output when the first n-type field-effect transistor is activated, a second n-type field-effect transistor coupled at its non-gate terminals between an output of the driver system and a second terminal of the supply voltage and configured to drive the output when the second n-type field-effect transistor is activated, a high-side capacitor coupled to the output of the driver system, and a low-side capacitor coupled to the second terminal of the supply voltage, wherein the high-side capacitor and the low-side capacitor are configured to track and correct for mismatches between a first resistance of the first n-type field-effect transistor and a second resistance of the second n-type field-effect transistor.

A transmitter includes a driving circuitry configured to drive a channel coupled to an output node by controlling an output impedance of a pull-up path, an output impedance of a pull-down path, or both, according to one or more multi-bit data signals, a pull-up control signal, and a pull-down control signal; a driving control circuit configured to generate the pull-up control signal and the pull-down control signal according to one or more calibration signals and the multi-bit data signals or according to the calibration signals and one or more duplicate multi-bit data signals, the duplicate multi-bit data signals duplicating the multi-bit data signals; and a look-up table storing values of the calibration signals.

To provide a hysteresis comparator having a small circuit area and low power consumption. The hysteresis comparator includes a comparator, a switch, a first capacitor, a second capacitor, and a logic circuit. A first terminal of the switch is electrically connected to one of a pair of conductive regions of the first capacitor, one of a pair of conductive regions of the second capacitor, and a first input terminal of the comparator. An output terminal of the comparator is electrically connected to an input terminal of the logic circuit. An output terminal of the logic circuit is electrically connected to the other of the pair of conductive regions of the second capacitor. The logic circuit has a function of generating an inverted signal of a signal input to the input terminal of the logic circuit and outputting the inverted signal to the output terminal of the logic circuit. A reference potential is input to the first input terminal of the comparator and the reference potential is held by the switch. Due to change in the potential of the output terminal of the comparator, the reference potential is changed by capacitive coupling of the second capacitor.

An impedance calibration circuit includes a first code generation circuit connected to a first reference resistor, and configured to generate a first code for forming a resistance based on the first reference resistor, by using the first reference resistor; a second code generation circuit configured to form a resistance of a second reference resistor less than the resistance of the first reference resistor, based on the first code, and generate a second code by using the second reference resistor; and a target impedance code generation circuit configured to generate a target impedance code based on the first code, the second code, and a target impedance value, and form an impedance having the target impedance value in a termination driver connected to the impedance calibration circuit, based on the target impedance code.

A charge amplifier circuit is provided. The charge amplifier circuit is couplable to a transducer that generates an electrical charge that varies with an external stimulus. The charge amplifier circuit includes an amplification stage having an input node, couplable to the transducer, and an output node. The amplification stage biases the input node at a first direct current (DC) voltage. The charge amplifier circuit includes a feedback circuit, which includes a feedback capacitor, electrically coupled between the input and output nodes of the amplification stage. The feedback circuit includes a resistor electrically coupled to the input node, and a level-shifter circuit, electrically coupled between the resistor and the output node. The level-shifter circuit biases the output node at a second DC voltage and as a function of a difference between the second DC voltage and a reference voltage.

A transmission device according to the disclosure includes a driver section that is able to transmit a data signal by using three or more predetermined number of voltage states and set voltages in each of the voltage states; and a control section that sets an emphasis voltage that is based on a transition among the predetermined number of the voltage states, and thereby causes the driver section to perform emphasis.

Methods and devices for wired charging and communication with a wearable device are described. In one embodiment, a symmetrical contact interface comprises a first contact pad and a second contact pad, and particular wired circuitry is coupled to the first and second contact pad to enable charging as well as receive and transmit communications via the contact pads as part of various device states.