Neural network circuit

A neural network circuit that uses a ramp function as an activation function, the neural network circuit comprising:

• a memory device including memristors being variable resistance elements connected in a matrix, wherein the memristors serve as memory elements of the memory device and the memory device is driven by a voltage applied thereto;
• a plurality of current-to-voltage (I-V) conversion amplification circuits that convert currents flowing via the memory elements into voltages and output the voltages;
• a differential amplifier circuit that performs a differential operation on outputs of two I-V conversion amplification circuits forming a pair included in the plurality of I-V conversion amplification circuits;
• an analog-to-digital (A-D) converter that performs an A-D conversion on a result of the differential operation of the differential amplifier circuit;
• and
• an output determiner that:
• by referring to input signals of the differential amplifier circuit, performs a first determination of whether a value of an output signal of the differential amplifier circuit belongs to an active region or an inactive region according to the ramp function being a positive polarity or a negative polarity;
• and
• based on a result of the first determination, switches over the differential amplifier circuit and the A-D converter between an operating state and a standby state.