Patent ID: 8437177
Filing Date: 2013-05-07
Classification: G11C,H03K

Abstract:
1. A nonvolatile latch circuit comprising: a first logic inversion circuit; a second logic inversion circuit having an input terminal connected to an output terminal of said first logic inversion circuit and an output terminal connected to an input terminal of said first logic inversion circuit; a first transistor which includes a first terminal, a second terminal, and a first control terminal, and controls a conduction state between the first terminal and the second terminal in accordance with a voltage of the first control terminal; a second transistor which includes a third terminal, a fourth terminal, and a second control terminal, and controls a conduction state between the third terminal and the fourth terminal in accordance with a voltage of the second control terminal; and a variable resistance element having a structure in which an oxide layer including an oxygen-deficient transition metal oxide is interposed between first and second electrodes, wherein the first terminal of said first transistor and the first electrode of said variable resistance element are connected to each other via a first node, the fourth terminal of said second transistor and the second electrode of said variable resistance element are connected to each other via a second node, the output terminal of said first logic inversion circuit and the second terminal of said first transistor are connected to each other via a third node, and the output terminal of said second logic inversion circuit and the third terminal of said second transistor are connected to each other via a fourth node, said variable resistance element changes to a first resistance state under application of a voltage higher than a first predetermined voltage between the first electrode and the second electrode so as to cause a current to flow in a direction from the first electrode to the second electrode, and changes to a second resistance state having a resistance value larger than a resistance value of the first resistance state under application of a voltage higher than a second predetermined voltage between the first electrode and the second electrode so as to cause a current to flow in a direction from the second electrode to the first electrode, and an absolute value of a first current that flows through said variable resistance element when said variable resistance element is caused to change from the second resistance state to the first resistance state is smaller than an absolute value of a second current that flows through said variable resistance element when said variable resistance element is caused to change from the first resistance state to the second resistance state.