| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit for generating refresh period in which temperature dependency of the refresh period of a DRAM cell is adequately compensated, operating margin is small and electric current consumption is reduced. SOLUTION: A refresh period generating circuit 001 is provided with: an oscillation circuit section 002 which oscillates at frequency having temperature dependency on the ambient temperature; a frequency dividing circuit 015 which divides the oscillation output of the oscillation circuit section 002; a temperature detector 018 which detects the ambient temperature; and a selection circuit 017, which switches the frequency divided output of a plurality of frequencies from the frequency-dividing circuit 015, based on the output of the temperature detector 018 and selectively outputs the switched output that becomes the reference of the refresh period. The temperature dependence of the oscillation frequency of the oscillation circuit section 002 has a positive temperature coefficient within a prescribed temperature range; whereas no positive temperature coefficient is provided outside the prescribed temperature range and the selecting circuit 017 conducts the switching of the frequency dividing output outside the prescribed temperature range. COPYRIGHT: (C)2006,JPO&NCIPI
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