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 semiconductor memory device, comprising:
an array of memory cells; and
a memory array interface circuit coupled to the array of memory cells, the memory array interface comprising:
a first delay means for delaying a wordline timing pulse by a first predetermined delay amount to provide a first delayed wordline timing pulse;
a first logic circuit, coupled to the first delay means, for logically combining the wordline timing pulse and the first delayed wordline timing pulse to provide a sense amplifier enable signal;
a second delay means for delaying the wordline timing pulse by a second predetermined delay amount, that is greater than the first predetermined delay amount, to provide a second delayed wordline timing pulse;
a second logic circuit, coupled to the second delay means, for logically combining the wordline timing pulse and the second delayed wordline timing pulse to provide a column select enable signal; and
enabling circuitry, coupled to the first and second logic circuits and to a sense amplifier power supply circuit of the memory array and a plurality of column access devices of the memory array, the enabling circuitry being configured to enable:
the sense amplifier power supply circuit in response to the sense amplifier enable signal, and
selected ones of the plurality of column access devices in response to the column select enable signal, after the sense amplifier power supply circuit is enabled.
2. The semiconductor memory device of claim 1 , wherein the memory cells are Dynamic Random Access Memory (DRAM) cells.
3. The semiconductor memory device of claim 1 , wherein the memory array interface circuit is a Static Random Access Memory (SRAM) interface.
4. The semiconductor memory device of claim 1 , wherein the wordline timing pulse, the sense amplifier enable signal and column select enable signal are all local with respect to said memory array.
5. The semiconductor memory device of claim 1 , wherein the first delay means is a first delay element.
6. The semiconductor memory device of claim 5 , wherein the second delay means comprises a comparator having a first input coupled to a power signal of the sense amplifier power supply circuit and a second input coupled to a predetermined threshold voltage, the comparator having an output that is asserted in response to a comparison between the first and second inputs.
7. The semiconductor memory device of claim 6 , wherein the output of the comparator is asserted if the power signal is greater than the predetermined threshold voltage.
8. The semiconductor memory device of claim 7 , wherein the power signal is a p-channel power signal.
9. The semiconductor memory device of claim 6 , wherein the output of the comparator is asserted if the power signal is less than the predetermined threshold voltage.
10. The semiconductor memory device of claim 9 , wherein the power signal is an n-channel power signal.
11. The semiconductor memory device of claim 1 , wherein the second delay means is a second delay element.
12. The semiconductor memory device of claim 11 , wherein the second delay element is coupled with the wordline timing pulse via a first delay element.
13. The semiconductor memory device of claim 11 , wherein the second delay element is directly coupled to the wordline timing pulse.
14. The semiconductor memory device of claim 1 , further comprising a plurality of logic circuits for logically combining the column select enable signal with a plurality of column address signals for enabling the selected ones of a plurality of column access devices.