Semiconductor memory device
View Patent ↗A Static Random Access Memory (SRAM) includes word lines WL, bit lines BL, address decoders that select one of the word lines WL in response to an address signal AD, a sense amplifier that is activated in response to a sense amplifier enable signal SAE, and a sense amplifier control circuit that generates the sense amplifier enable signal SAE. In this device, the more distant the word line WL is from the sense amplifier, the longer the sense amplifier control circuit sets the delay time of the sense amplifier enable signal SAE so that the more distant the word line WL is from the sense amplifier, the later the sense amplifier is activated.
1. A semiconductor memory device comprising:
a plurality of word lines arranged in rows;
a plurality of bit lines arranged in columns;
an address decoder that selects one of the word lines in response to an address signal;
a sense amplifier that amplifies potentials generated on the bit lines; and
a sense amplifier control circuit in which the more distant the word line selected by the address decoder is from the sense amplifier, the later the sense amplifier is activated, wherein the sense amplifier is activated in response to a sense amplifier enable signal, and the sense amplifier control circuit includes a delay time adjustment circuit in which the more distant the word line selected by the address decoder is from the sense amplifier, the longer a delay time of the sense amplifier enable signal is set and a pulse width adjustment circuit in which the more distant the word line selected by the address decoder is from the sense amplifier, the narrower a pulse width of the sense amplifier enable signal is set.
2. The semiconductor memory device according to claim 1 , wherein the sense amplifier control circuit dynamically controls a timing of activation of the sense amplifier in response to the address signal.
3. The semiconductor memory device according to claim 1 , wherein the delay time adjustment circuit includes:
one or more delay elements that delay the sense amplifier enable signal; and
means for changing the number of the delay elements.
4. The semiconductor memory device according to claim 1 , wherein the pulse width adjustment circuit includes a one shot pulse generation circuit, the one shot pulse generation circuit includes:
an odd number of inverters; and
an AND circuit that accepts an input signal of the one shot pulse generation circuit and an output signal of the last inverter out of the odd number of inverters, and
the pulse width adjustment circuit includes means for changing the number of the inverters.
5. A method for activating a sense amplifier in a semiconductor memory device, the method comprising the steps of:
activating the sense amplifier at a first timing when a first word line is selected from a plurality of word lines; and
activating the sense amplifier at a second timing later than the first timing when a second word line is selected from the plurality of word lines, the second word line being more distant from the sense amplifier than the first word line is from the sense amplifier, wherein the sense amplifier is activated in response to a sense amplifier enable signal, and the sense amplifier control circuit includes a delay time adjustment circuit in which the more distant the word line is from the sense amplifier, the longer a delay time of the sense amplifier enable signal is set and a pulse width adjustment circuit in which the more distant the word line is from the sense amplifier, the narrower a pulse width of the sense amplifier enable signal is set.