| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a semiconductor memory which allows a circuit, which reads fine differences in current value, such as a multivalued semiconductor memory, to be stably operated by installing a reference current source such that the size relation between the current value of the reference current source and that of the cell transistor is fixed even when the power source potential varies in the reference current generating circuit of the reading circuit of the semiconductor memory. SOLUTION: Clamp potentials of VW 1 are set by lowering the potential of a word line power source stepwise each by a definite potential and by inputting to transistors N1-3 to N1-5, and the individual clamp potentials which are divided by resistors are inputted into the transistors N1-6 to N1-8 for reference current sources. By this, Vt's are individually set by the clamp potentials and the slope of VG-ID can be adjusted by the resistor ratios. Accordingly, since the word potential-vs.-ID characteristic of individual reference current sources three in total is equivalent to the slope of the cell transistor and Vts are set individually, correct operation is secured even when the power source potential varies.</p> |
