1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly to a reference voltage generating circuit for, for example, a sense amplifier incorporated in a semiconductor memory using a ferroelectric capacitor.
2. Description of the Related Art
In the prior art, it is considered that the peak-to-peak midpoint of the signal value distributions obtained when data “0” and “1” have been read at a low temperature is identical to that of the signal value distributions obtained when data “0” and “1” have been read at a high temperature, and therefore that it is not necessary to make a reference voltage for a sense amplifier depend on temperature (the signal value distribution(s) obtained when data “0” and/or “1” has been read will be hereinafter referred to as “0” and/or “1” signal distribution). In other words, a predetermined reference voltage is used for the voltage read from each memory cell to a corresponding bit line.
However, the “1” signal distribution at a low temperature has a tail, whereas the “1” signal distribution at a high temperature dose not have a long tail. Therefore, at a high temperature, the midpoint of the window defined between the tails of the “0” “1” signal distributions has a high value. This fact is passed unnoticed in the prior art.
USPTO Backgrounds
USPTO Backgrounds