| 摘要 |
PURPOSE:To avoid the process variation to the timer cycle by driving a timer circuit with an external clock. CONSTITUTION:A timer circuit consists of a buffer part including transistors TrQ12 and Q13, a charge pump part including TrQ7-Q9 and capacities C1 and C2, and an output inverter part including TrQ10 and Q11. The buffer part is driven by an external clock WE. The variation of the timer cycle is reduced by an amount equivalent to the process variation of the oscillator cycle. Thus it is possible to always set the timer cycle at a level close to the refresh cycle of a memory cell. This reduces the power consumption. |
