Abstract: An amplifying device comprising a first terminal to which an alternating signal is inputted; a second terminal connected via an external first resistor to a power supply line; a third terminal to be grounded; a second resistor provided on a signal line in between the second terminal and the third terminal; a differential amplifier, the alternating signal of which being inputted through the first terminal to one input terminal and an output according to the alternating signal being fed back to the other input terminal via a signal line in between the second terminal and the second resistor, and between the one input terminal and the other input terminal, a positive offset voltage higher than a maximum level of the alternating signal being produced in advance; and a third resistor provided between a signal line joining the first terminal and the one input terminal, and a signal line leading to the third terminal.

Abstract: An amplifying device comprising a first terminal to which an alternating signal is inputted; a second terminal connected via an external first resistor to a power supply line; a third terminal to be grounded; a second resistor provided on a signal line in between the second terminal and the third terminal; a differential amplifier, the alternating signal of which being inputted through the first terminal to one input terminal and an output according to the alternating signal being fed back to the other input terminal via a signal line in between the second terminal and the second resistor, and between the one input terminal and the other input terminal, a positive offset voltage higher than a maximum level of the alternating signal being produced in advance; and a third resistor provided between a signal line joining the first terminal and the one input terminal, and a signal line leading to the third terminal.