Method and apparatus for synchronization of row and column access operations
View Patent ↗A circuit for synchronizing row and column access operations in a semiconductor memory having an array of bit line pairs, word lines, memory cells, sense amplifiers, and a sense amplifier power supply circuit for powering the sense amplifiers, the circuit comprising, a first delay circuit for delaying a word line timing pulse by a first predetermined period, a first logic circuit for logically combining the word line timing pulse and the delayed word line timing pulse to produce a sense amplifier enable signal, for enabling a sense amplifier power supply circuit, a second delay circuit for delaying the word line timing pulse by a second predetermined period, and a second logic circuit for logically combining the word line timing pulse and the second delayed word line timing pulse to produce a column select enable signal, for enabling selected ones of a plurality of column access devices wherein the second predetermined time period is selected so that ones of a plurality of column access devices are activated after the sense amplifier power supply circuit is enabled.
1. A Random Access Memory (RAM), comprising:
(a) at least one memory array comprising plurality of bit line pairs, plurality of word lines and plurality of memory cells for storing and retrieving binary data;
(b) a set of bit line sense amplifiers for sensing and enhancing differential signals between bit lines of said bit line pairs;
(c) a set of column access devices for coupling said bit line pairs to data lines;
(d) a bit line sense amplifier power supply circuit for powering said bit line sense amplifiers;
(e) first and second delay circuits for delaying a word line timing pulse by predetermined periods of time, the first and second delay circuits being coupled in series so that the first delay circuit delays the word line timing pulse by a first period of time and the second delay circuit adds to the first delay, thus providing a further delayed version of the word line timing pulse;
(f) a first logic circuit for logically combining said word line timing pulse and the delayed version of the word line timing pulse to produce a bit line sense amplifier enable signal, for enabling the bit line sense amplifier power supply circuit; and
(g) a second logic circuit far logically combining said word line timing pulse and the further delayed version of the word line timing pulse to produce a column select enable signal.
2. The Random Access Memory (RAM) as claimed in claim 1 , wherein said memory cells are Dynamic Random Access Memory (DRAM) cells.
3. The Random Access Memory (RAM) as claimed in claim 1 , wherein said word line timing pulse is logically combined with a pre-decoded row address by a third logic circuit in order to raise one of the said word lines selected by the row address.
4. The Random Access Memory (RAM) as claimed in claim 1 , wherein said column select enable signal is logically combined with a plurality of pre-decoded y-addresses by a plurality of fourth logic circuits in order to enable selected ones of a plurality of column access devices.
5. The Random Access Memory (RAM) as defined in claim 1 , wherein the time delay introduced by said second delay circuit is longer than the time delay time introduced by said first delay circuit.
6. The Random Access Memory (RAM) as defined in claim 5 , wherein the time delay introduced by said first and second delay circuits is controlled with precision.
7. The Random Access Memory (RAM) as defined in claim 1 , wherein said word line timing pulse, bit line sense amplifier enabling signal and column select enable signal are all local with respect to said memory array.
8. The Random Access Memory (RAM) as chimed in claim 4 , wherein said first, second, third and fourth logic circuits are all local with respect to said memory array.
9. The Random Access Memory (RAM) as claimed in claim 1 , wherein said first and second delay circuits are both local with respect to said memory array.