| 摘要 |
PURPOSE:To prevent deterioration of a write transistor (TR) due to a read current by short-circuiting the diode junction of a cell by a write current to write information and providing a read TR in addition to a write TR. CONSTITUTION:In bringing terminals E, F at write to a high voltage level and flowing forcibly a current from a terminal C to a terminal D, a cathode voltage of a diode 16 rises and exceeds reverse dielectric strength and breaks down, then a current flows to the terminal D, a TR 14 is turned on to absorb a large current. The junction of the diode 16 is short-circuited by the heat energy generated in this case. In supplying a read current from the terminal E to the terminal F, since a base of a TR 18 is at a low level at the write state, no current flows, but the base at non-write state is at a high level (Vcc), then the TR 18 is turned on to detect the read current. Thus, even when the read current is increased due to high read speed, the destruction of a cell is not incurred. |
