Semiconductor memory device
View Patent ↗A reference cell outputs a reference current of a data reading current of a memory cell. A trimming data in accordance with the reference current is memorized in a non-volatile memory cell. A standard current generator outputs a standard current whose current quantity is adjusted in accordance with the trimming data. A current comparator compares the standard current to the reference current. The output of the reference current from the reference cell is adjusted through a reference cell adjuster based on a result of the comparison by the current comparator.
1. A semiconductor memory device comprising:
a memory cell;
a reference cell for outputting a reference current of a data reading current of the memory cell;
a non-volatile memory cell for memorizing a trimming data in accordance with the reference current;
a standard current generator for outputting a standard current in a state where a current quantity is adjusted in accordance with the trimming data;
a current comparator for comparing the standard current to the reference current; and
a reference cell adjuster for adjusting an output of the reference current from the reference cell based on a result of the comparison by the current comparator.
2. The semiconductor memory device as claimed in claim 1 , wherein the reference cell adjuster adjusts an output of the reference current by rewriting a threshold voltage of the reference cell.
3. The semiconductor memory device as claimed in claim 1 , wherein the reference cell has a structure equal to the memory cell to output the reference current.
4. The semiconductor memory device as claimed in claim 1 , further comprising an AD converter for converting the reference current into a digital value, wherein the non-volatile memory cell memorizes the digital value as the trimming data.
5. The semiconductor memory device as claimed in claim 1 , further comprising an adjustment necessary/unnecessary judger for judging whether or not adjustment of the reference cell is necessary based on a result of the comparison by the current comparator, wherein the reference cell adjuster adjusts the reference cell based on a result of judgment of the adjustment necessary/unnecessary judger.
6. The semiconductor memory device as claimed in claim 1 , wherein the reference cell adjuster adjusts the reference cell based on a result of the comparison by the current comparator or an external input signal.
7. The semiconductor memory device as claimed in claim 1 , further comprising a data corrector for correcting the trimming data in accordance with temperature characteristics of the standard current and the reference current.
8. The semiconductor memory device as claimed in claim 7 , wherein the data corrector corrects the trimming data in accordance with temperature characteristics of a plurality of temperature ranges of the standard current and the reference current.
9. The semiconductor memory device as claimed in claim 1 , further comprising:
a temperature detector for detecting an ambient temperature of the semiconductor memory device, and
a data corrector for correcting a trimming data retrieved from the non-volatile memory cell in accordance with a result of detection in the temperature detector.