Abstract: A semiconductor device includes: an amplifier circuit that has an inverting input terminal, a non-inverting input terminal, and an output terminal; a first variable voltage source that generates a first bias voltage having a voltage value corresponding to a first set value; a second variable voltage source that generates a second bias voltage having a voltage value corresponding to a second set value; a first resistor whose one end is connected to the inverting input terminal; a second resistor that is connected between the output terminal and the inverting input terminal; a third resistor whose one end is connected to the non-inverting input terminal; and a fourth resistor that is connected between the second variable voltage source and the non-inverting input terminal. The first bias voltage is provided to the other end of the first resistor. An input signal is provided to the other end of the third resistor.

Abstract: A semiconductor device includes: an amplifier circuit that has an inverting input terminal, a non-inverting input terminal, and an output terminal; a first variable voltage source that generates a first bias voltage having a voltage value corresponding to a first set value; a second variable voltage source that generates a second bias voltage having a voltage value corresponding to a second set value; a first resistor whose one end is connected to the inverting input terminal; a second resistor that is connected between the output terminal and the inverting input terminal; a third resistor whose one end is connected to the non-inverting input terminal; and a fourth resistor that is connected between the second variable voltage source and the non-inverting input terminal. The first bias voltage is provided to the other end of the first resistor. An input signal is provided to the other end of the third resistor.

Abstract: Disclosed is a differential decoder circuit, which has: a pair of first and second transistors which form a differential connection, wherein a base of the first transistor is supplied with a reference bias voltage and a base of the second transistor is supplied with an input signal to be decoded to thereby output a decode output depending on the input signal from collector outputs of the first and second transistors; a constant-voltage source; a first bias means for supplying a bias voltage determined by a constant voltage of the constant-voltage source with the base of the first transistor; and a second bias means for supplying the alternative of a voltage determined by the input signal and the voltage determined by the constant voltage depending on a level of the input signal with the base of the second transistor.