There is provided a printer including a motor configured to convey a medium and a processor configured to control the motor. The processor acquires a signal corresponding to a counterelectromotive force of the motor and performs predetermined processing based on the acquired signal.

A display driver includes a D/A converter circuit for outputting a gradation voltage, and an amplifier circuit that is input with a gradation voltage at an input node. The amplifier circuit includes an operational amplifier, resistance provided between the input node and a node, resistance provided between a node and an output node of the operational amplifier, and an adjustment resistance circuit. The adjustment resistance circuit adjusts a first adjustment resistance value, that is a resistance value between a node and an inverting input node of the operational amplifier, and a second adjustment resistance value, that is a resistance value between the node and the inverting input node.

Apparatuses and techniques are described for calibrating a negative voltage source. A ground voltage is applied to a multi-stage amplifier from the negative voltage source while an offset voltage measurement (OVM) is made at the output of the multi-stage amplifier. The OVM is recorded and subsequently used by a calibration circuit when the negative voltage source applies a range of negative voltages to the input of the multiple stage amplifier. The calibration circuit subtracts the OVM from measurements obtained at the output of the multi-stage amplifier to obtain corrected measurements, and uses the corrected measurements to calibrate the negative voltage source, e.g., by adjusting a relationship between digital values input to the negative voltage source and the output voltages.

In a general aspect, a circuit can include an input circuit configured to receive an input signal, and an amplifier circuit coupled with the input circuit. The amplifier circuit can include an amplifier, and first and second feedback paths. The first feedback path can be from a positive output to a negative input of the amplifier, and the second feedback path can be from a negative output to a positive input of the first amplifier. The circuit can also include a loop circuit configured to provide a local feedback loop for the first amplifier and configured to control current flow into the positive input of the first amplifier and current flow into the negative input of the first amplifier. The circuit can also include a control circuit that is configured to enable the loop circuit in response to a magnitude of the input signal exceeding a threshold.

A circuit comprises a sensing resistor with a resistance Rs, a first amplifier circuit with a first gain factor G, a second amplifier circuit with a second gain factor (1/A), a third amplifier circuit, a current mirror, a buffer, and a peak voltage detector. The first amplifier circuit is coupled to the sensing resistor at a first node and a second node and to the second amplifier circuit, which is further coupled to the current mirror. The buffer is coupled to the current mirror and to the third amplifier circuit, which is further coupled to the peak voltage detector and configured to receive a voltage across a load and a voltage on a ground node. In some implementations, the load is a speaker. In some implementations, a filter is coupled between the first and the second amplifier circuits.

An apparatus includes a plurality of transmitter channels and a plurality of feedback networks. Each of the plurality of transmitter channels may be coupled to a respective antenna element in a respective group of antenna elements of a phased array antenna. Each of the transmitter channels generally comprises a power amplifier circuit configured to drive the respective antenna element in the respective group of antenna elements to produce and steer a radio-frequency beam. Each of the plurality of feedback networks may be coupled between an output and an input of a respective power amplifier circuit of a respective transmitter channel. Each of the feedback networks generally comprises a resistor and a capacitor connected in series. The respective power amplifier circuit with the feedback network generally maintains a power matching condition with load variation associated with performing beam steering of the radio-frequency beam using the antenna elements of the phased array antenna.

Described herein are DACs with low distortion for high dynamic range (HDR), extremely high dynamic range (EHDR), and other suitable applications. Some embodiments relate to a device including a DAC configured for coupling to an amplifier via a force path and a sense path. For example, the DAC may provide output current to the amplifier via the force path, and the DAC may sense the input voltage of the amplifier via the sense path. Accordingly, distortion such as harmonic distortion and/or gain offset from parasitic impedances in the force and/or sense paths may be reduced or eliminated. Some embodiments relate to a DAC including a voltage reference generator configured to compensate for variations in impedances of the DAC, such as due to semiconductor process variation. Accordingly, distortion in the DAC output due to variations in the DAC impedances may be reduced or eliminated.

A display driver includes an operational amplifier, a D/A conversion circuit, a resistance circuit, and a resistance element. The D/A conversion circuit includes first and second variable resistance circuits including one end to which first and second voltages are input and another end connected to an inverting input node. The resistance circuit is provided between the inverting input node and an output node. The resistor is provided between the output node and the inverting input node. A resistance value of the first variable resistance circuit is set based on upper bit data of display data. A resistance value of the second variable resistance circuit is set based on lower bit data of the display data.

A virtual resistive load feedback circuit for driving a piezoelectric actuator is provided that accounts for a hysteresis error and drift within the movement of the actuator. The circuit may include a voltage divider and charge divider. A voltage monitor signal corresponding to a voltage of a driver signal and a current monitor signal corresponding to a current provided to the amplifier are combined by an operational amplifier and include electrical characteristics of the actuator such that the circuit approximates a virtual load across the actuator. A feedback portion of the operational amplifier may include a resistor and capacitor connected in parallel to provide the voltage and charge divide functions. The use of the virtual resistive circuit allows for the piezoelectric actuator to be ground referenced, with no external components connected directly to the actuator while gaining the feedback effect to counter the hysteresis and drifts errors of the actuator.

A calibration circuit configured to calibrate a signal of a sensing unit comprises: an amplifier, a first impedance element and a second impedance element. The amplifier has a first input terminal, a second input terminal and an output terminal. The first input terminal is coupled to a first terminal of the sensing unit, the second input terminal is coupled to a reference voltage, and the output terminal is feedback to the first input terminal and outputs the readout signal. A first terminal of the first impedance element is coupled to the first input terminal of the amplifier, and a second terminal of the first impedance element is coupled to a calibration voltage. A first terminal of the second impedance element is coupled to the first terminal of the first impedance element, and a second terminal of the second impedance element is coupled to the output terminal of the amplifier.