Liquid ejecting apparatus, drive circuit, and head unit

A drive circuit that drives a capacitive load using a drive signal, comprising:

• a differential amplifier that outputs a control signal based on a source drive signal which is a source signal of the drive signal and a signal based on the drive signal;
• a pair of transistors that include a high-side transistor and a low-side transistor which are controlled based on the control signal and outputs the drive signal from an output terminal;
• a selector that selects one of the high-side transistor and the low-side transistor and supplies the control signal to the selected transistor;
• a first resistance element for pulling up the output terminal;
• and
• a second resistance element for pulling down the output terminal, wherein
• the selector selects a transistor to which the control signal is supplied, based on a logic level of a predetermined select signal,
• the select signal designates selection in the select unit, based on a voltage of the source drive signal, and the logic level of the select signal is inverted for a predetermined period when a difference between a voltage of the source drive signal and a voltage of a signal based on the drive signal is larger than or equal to a threshold value.

A head unit comprising:

• a piezoelectric element which is displaced by a drive signal being applied to the piezoelectric element;
• and
• an ejecting unit that includes the piezoelectric element and ejects liquid in accordance with displacement of the piezoelectric element,
• wherein the ejecting unit is driven by a drive circuit which includes,
• a differential amplifier that outputs a control signal based on a source drive signal which is a source signal of the drive signal and a signal based on the drive signal;
• a pair of transistors that include a high-side transistor and a low-side transistor which are controlled based on the control signal and outputs the drive signal from an output terminal;
• a selector that selects one of the high-side transistor and the low-side transistor and supplies the control signal to the selected transistor;
• a first resistance element for pulling up the output terminal;
• and
• a second resistance element for pulling down the output terminal,
• wherein the selector selects a transistor to which the control signal is supplied, based on a logic level of a predetermined select signal,
• wherein the select signal designates selection in the select unit, based on a voltage of the source drive signal, and
• wherein the logic level of the select signal is inverted for a predetermined period when a difference between a voltage of the source drive signal and a voltage of a signal based on the drive signal is larger than or equal to a threshold value.