Semiconductor memory device

A semiconductor memory device comprising:

• a reference temperature signal output circuit for outputting a reference temperature signal from a plurality of reference temperature signals corresponding to a plurality of different temperature;
• a temperature comparator circuit for comparing a temperature signal with said reference temperature signal, the temperature signal indicating a temperature of the semiconductor memory device;
• and
• a refresh period control circuit for changing a refresh frequency according to the output signal of said temperature comparator circuit,
• wherein the reference temperature signal is selected from the plurality of reference temperature signals based on the output signal of said temperature comparator circuit.

A semiconductor memory device arranged to perform a refreshing operation to holding data, comprising:

• a temperature detector circuit configured to output a temperature signal;
• a reference temperature signal output circuit configured to output a single reference temperature signal from a plurality of different reference temperatures signals to be compared with said temperature signal;
• a temperature comparator circuit configured to compare said temperature signal with said single reference temperature signal;
• and
• an oscillator circuit configured to change a refresh frequency according to the output signal of said temperature comparator circuit,
• wherein the temperature comparator includes a single differential amplifier for comparing said temperature signal with said single reference temperature signal.