| 摘要 |
PURPOSE: A source bias supplying circuit of a flash memory is provided to offsets threshold voltage drop by applying more than fixed positive voltage to a source line of each cell. CONSTITUTION: In a read operation, because a program signal(PROGRAM) and a recovery signal(RECOVERY) are low signals, an NMOS transistor(N2) is turned off. And, because a read signal(READ) and an erase signal(ERASE) are low signals, a PMOS transistor(P1) is turned on, and an NMOS transistor(N1) is turned on. For this reason, a potential of a node A is the sum of threshold voltages of a diode(D1) and an NMOS transistor(N1), and the node A applies a voltage(Vs) by being connected to a source line. When a fixed voltage is applied to the source line, a threshold voltage of a cell is increased as much as the fixed voltage. In conclusion, when the threshold voltage is increased, a drop of the threshold voltage is offset.
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