| 摘要 |
The present invention relates to a nonvolatile memory cell comprising two nonvolatile alterable threshold voltage field effect transistors. The drain electrodes of the two nonvolatile alterable threshold voltage field effect transistors are coupled through load transistors to a common negative power supply. Their gates are connected together and to an external source of negative pulses. Their sources are connected to circuits sensitive to current in the two alterable transistors. The first nonvolatile alterable threshold voltage field effect transistor is placed at a first threshold voltage, and the second alterable threshold voltage field effect transistor is placed at a second threshold voltage. The different threshold voltages set the nonvolatile memory cell in a one state or in a zero state. A current will first pass through the alterable threshold voltage field effect transistor having the less negative threshold voltage, before it passes through the alterable threshold field effect transistor having the more negative threshold voltage during the application of a negatively increasing gate voltage to both alterable threshold voltage field effect transistors. The state of the nonvolatile memory cell is thus determined by which nonvolatile alterable threshold voltage transistor conducts first.
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