Capacitive load driving amplifier

An electronic amplifier for driving a capacitive load having first and second terminals, the electronic amplifier comprising:

• first and second differential input terminals configured to receive an input signal;
• first and second differential output terminals configured to be respectively coupled to the first and second terminals of the capacitive load and to provide a differential output signal to the capacitive load;
• a first single ended operational device having first and second differential inputs and an output coupled to said first differential output terminal;
• first and second resistors configured to couple, respectively, said first and second differential inputs of said first single ended operational device to said first and second differential input terminals;
• a second single ended operational device having first and second differential inputs coupled to said first and second differential input terminals, respectively, and an output coupled to said second differential output terminal;
• third and fourth resistors configured to couple, respectively, said first and second differential inputs of said second single ended operational device to said first and second differential input terminals;
• a fifth resistor configured to couple said first differential output terminal to said first differential input of said first single ended operational device;
• a sixth resistor configured to couple said second differential output terminal to said second differential input of said second single ended operational device;
• a seventh resistor configured to couple said second differential input of said first single ended operational device to a reference voltage;
• and
• an eighth resistor configured to couple said first differential input of said second single ended operational device to the reference voltage;
• the ratio of a resistance value of said fifth resistor over a resistance value of said first resistor being equal to the ratio of a resistance value of said seventh resistor over a resistance value of said second resistor and also being equal to the ratio of a resistance value of said sixth resistor over a resistance value of the fourth resistor;
• said first and second single ended operational devices being configured to set said first and second differential output terminals and the first and second terminals of the capacitive load at a reference voltage to discharge the first and second terminals of the capacitive load during periods where an amplitude of the differential output signal decreases.

An electronic apparatus comprising an electronic amplifier configured to operate as a driver for at least one of a piezoelectric actuator and an embedded piezoelectric speaker, each having first and second terminals, the electronic amplifier comprising:

• first and second differential input terminals configured to receive an input signal;
• first and second differential output terminals configured to be respectively coupled to the first and second terminals of the at least one of a piezoelectric actuator and an embedded piezoelectric speaker and to provide a differential output signal to the first and second terminals of the at least one of a piezoelectric actuator and an embedded piezoelectric speaker;
• a first operational device having first and second differential inputs coupled to said first and second differential input terminals, respectively, and an output coupled to said first differential output terminal;
• and
• a second operational device having first and second differential inputs coupled to said first and second differential input terminals, respectively, and an output coupled to said second differential output terminal;
• said first and second operational devices being configured to set said first and second differential output terminals and the first and second terminals of the at least one of a piezoelectric actuator and an embedded piezoelectric speaker at a reference voltage to discharge the first and second terminals of the at least one of a piezoelectric actuator and an embedded piezoelectric speaker during periods where an amplitude of the differential output signal decreases.

A method of making an electronic amplifier for driving a capacitive load having first and second terminals, the method comprising:

• coupling first and second differential input terminals to receive an input signal;
• coupling first and second differential output terminals respectively to the first and second terminals of the capacitive load to provide a differential output signal to the first and second terminals of the capacitive load;
• coupling a first operational device having first and second differential inputs coupled to the first and second differential input terminals, respectively, and an output coupled to the first differential output terminal;
• and
• coupling a second operational device having first and second differential inputs coupled to the first and second differential input terminals, respectively, and an output coupled to the second differential output terminal;
• using the first and second operational devices to set the first and second differential output terminals and the first and second terminals of the capacitive load at a reference voltage to discharge the first and second terminals of the capacitive load during periods where an amplitude of the differential output signal decreases.