Patent ID: 8116112

Claim:
A semiconductor memory apparatus comprising: a upper bit line; a lower bit line; an upper local bit line; a lower local bit line; a first switch between the upper bit line and the upper local bit line, configured to control a connection between the upper bit line and the upper local bit line; a second switch between the lower bit line and the lower local bit line, configured to control a connection between the lower bit line and the lower local bit line; a first memory cell array comprising: a first memory cell connected to a first upper bit line and a first word line; and a second memory cell connected to a first lower bit line and the first word line; a second memory cell array comprising: a third memory cell connected to a second upper bit line and a second word line; and a fourth memory cell connected to a second lower bit line and the second word line; a first sense circuit connected to the upper and lower bit lines and configured to amplify a signal from the first to fourth memory cells; a third switch between the first upper bit line and the upper bit line, configured to control a connection between the first memory cell and the first sense circuit; a fourth switch between the first lower bit line and the lower bit line, configured to control a connection between the second memory cell and the first sense circuit; a fifth switch between the second upper bit line and the upper bit line, configured to control a connection between the third memory cell and the first sense circuit; a sixth switch between the second lower bit line and the lower bit line, configured to control a connection between the fourth memory cell and the first sense circuit; a second sense circuit connected to the upper and lower local bit lines and configured to amplify the signal amplified by the first sense circuit; and a dummy cell circuit connected to the upper and lower local bit lines, wherein the first switch disconnects the upper local bit line from the upper bit line while the second switch disconnects the lower local bit line from the lower bit line, when the first sense circuit amplifies the signal; and the first switch connects the upper local bit line to the upper bit line while the second switch connects the lower local bit line to the lower bit line, when the second sense circuit amplifies the signal amplified by the first sense circuit.