| 摘要 |
A ring oscillator composed of a plurality of series connected inverters, the number of which may be varied after fabrication of the ring oscillator by selectively programming selections between the output of the ring oscillator and the inputs of respective inverters. In the preferred embodiment of the invention, a logic gate receiving an enable signal is connected in series with the inverters to allow the ring oscillator to be selectively enabled. Programmable connections, such as laser fuses, metal fuses, or semiconductor switches, are connected between the output of the ring oscillator and the inputs of at least some of the inverters. The ring oscillator may be advantageously used to drive the voltage pump used in a conventional DRAM integrated circuit. The inventive ring oscillator may also be used to periodically trigger a refresh circuit in a DRAM integrated circuit.
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