Memory circuits with reduced leakage power and design structures for same
View Patent ↗A memory circuit includes a global read bit line, a global read bit line latch, and a plurality of sub-arrays, each of which includes first and second local read bit lines, first and second local write bit lines, and first and second pluralities of memory cells interconnected, respectively, with the first and second local read bit lines and the first and second local write bit lines. The local read bit lines are decoupled from the local write bit lines. A local multiplexing block is interconnected with the first and second local read bit lines and is configured to ground the first and second local read bit lines upon assertion of a SLEEP signal, and to selectively interconnect the local read bit lines to the global read bit line. A global multiplexing block is interconnected with the global read bit line and is configured to maintain the global read bit line in a substantially discharged state upon assertion of the SLEEP signal and to interconnect the global read bit line to the global read bit line latch. Also included are design structures for circuits of the kind described.
1. A memory circuit comprising:
a global read bit line;
a global read bit line latch;
a plurality of sub-arrays, each of said sub-arrays comprising:
a first local read bit line;
a first local write bit line;
a first plurality of memory cells interconnected with said first local read bit line and said first local write bit line, said first local read bit line being decoupled from said first local write bit line;
a second local read bit line;
a second local write bit line;
a second plurality of memory cells interconnected with said second local read bit line and said second local write bit line, said second local read bit line being decoupled from said second local write bit line; and
a local multiplexing block interconnected with said first and second local read bit lines and configured to ground said first and second local read bit lines upon assertion of a SLEEP signal and to selectively interconnect said local read bit lines to said global read bit line; and
a global multiplexing block interconnected with said global read bit line and configured to maintain said global read bit line in a substantially discharged state upon assertion of said SLEEP signal and to interconnect said global read bit line to said global read bit line latch.
2. The circuit of claim 1 , wherein each of said local multiplexing blocks comprises:
a first pair of series pull-up transistors having a power supply terminal and a terminal interconnected to said first local read bit line, a first transistor of said first pair of series pull-up transistors having a gate for receiving a local pre-charge signal and a second transistor of said first pair of series pull-up transistors having a gate for receiving said SLEEP signal;
a second pair of series pull-up transistors having a power supply terminal and a terminal interconnected to said second local read bit line, a first transistor of said second pair of series pull-up transistors having a gate for receiving a local pre-charge signal and a second transistor of said second pair of series pull-up transistors having a gate for receiving said SLEEP signal;
a first pull-down transistor having a first terminal interconnected to said first local read bit line, a grounded second terminal, and a gate for receiving said SLEEP signal;
a second pull-down transistor having a first terminal interconnected to said second local read bit line, a grounded second terminal, and a gate for receiving said SLEEP signal;
a NAND gate having first and second inputs interconnected, respectively, with said first and second local read bit lines, and having an output; and
a third pull-down transistor having a first terminal coupled to said global read bit line, a grounded second terminal, and a gate coupled to said output of said NAND gate.
3. The circuit of claim 2 , wherein said global multiplexing block comprises a pair of global series pull-up transistors having a power supply terminal and a terminal interconnected to said global read bit line, a first transistor of said pair of global series pull-up transistors having a gate for receiving a global pre-charge signal and a second transistor of said pair of global series pull-up transistors having a gate for receiving said SLEEP signal.
4. The circuit of claim 3 , further comprising a power supply and control block configured to:
provide a supply voltage to said power supply terminals of said first and second pairs of series pull-up transistors and said power supply terminal of said pair of global series pull-up transistors; and
provide said SLEEP signal.
5. The circuit of claim 4 , wherein said first and second pull-down transistors of said local multiplexing blocks are relatively small, as compared to at least some other transistors among said transistors in said circuit.
6. The circuit of claim 1 , wherein said global multiplexing block comprises a pair of global series pull-up transistors having a power supply terminal and a terminal interconnected to said global read bit line, a first transistor of said pair of global series pull-up transistors having a gate for receiving a global pre-charge signal and a second transistor of said pair of global series pull-up transistors having a gate for receiving said SLEEP signal.
7. A design structure embodied in a machine readable medium, said design structure comprising a memory circuit, said memory circuit comprising:
a global read bit line;
a global read bit line latch;
a plurality of sub-arrays, each of said sub-arrays comprising:
a first local read bit line;
a first local write bit line;
a first plurality of memory cells interconnected with said first local read bit line and said first local write bit line, said first local read bit line being decoupled from said first local write bit line;
a second local read bit line;
a second local write bit line;
a second plurality of memory cells interconnected with said second local read bit line and said second local write bit line, said second local read bit line being decoupled from said second local write bit line; and
a local multiplexing block interconnected with said first and second local read bit lines and configured to ground said first and second local read bit lines upon assertion of a SLEEP signal and to selectively interconnect said local read bit lines to said global read bit line; and
a global multiplexing block interconnected with said global read bit line and configured to maintain said global read bit line in a substantially discharged state upon assertion of said SLEEP signal and to interconnect said global read bit line to said global read bit line latch.
8. The design structure of claim 7 , wherein each of said local multiplexing blocks comprises:
a first pair of series pull-up transistors having a power supply terminal and a terminal interconnected to said first local read bit line, a first transistor of said first pair of series pull-up transistors having a gate for receiving a local pre-charge signal and a second transistor of said first pair of series pull-up transistors having a gate for receiving said SLEEP signal;
a second pair of series pull-up transistors having a power supply terminal and a terminal interconnected to said second local read bit line, a first transistor of said second pair of series pull-up transistors having a gate for receiving a local pre-charge signal and a second transistor of said second pair of series pull-up transistors having a gate for receiving said SLEEP signal;
a first pull-down transistor having a first terminal interconnected to said first local read bit line, a grounded second terminal, and a gate for receiving said SLEEP signal;
a second pull-down transistor having a first terminal interconnected to said second local read bit line, a grounded second terminal, and a gate for receiving said SLEEP signal;
a NAND gate having first and second inputs interconnected, respectively, with said first and second local read bit lines, and having an output; and
a third pull-down transistor having a first terminal coupled to said global read bit line, a grounded second terminal, and a gate coupled to said output of said NAND gate.
9. The design structure of claim 8 , wherein said global multiplexing block comprises a pair of global series pull-up transistors having a power supply terminal and a terminal interconnected to said global read bit line, a first transistor of said pair of global series pull-up transistors having a gate for receiving a global pre-charge signal and a second transistor of said pair of global series pull-up transistors having a gate for receiving said SLEEP signal.
10. The design structure of claim 9 , further comprising a power supply and control block configured to:
provide a supply voltage to said power supply terminals of said first and second pairs of series pull-up transistors and said power supply terminal of said pair of global series pull-up transistors; and
provide said SLEEP signal.
11. The design structure of claim 10 , wherein said first and second pull-down transistors of said local multiplexing blocks are relatively small, as compared to at least some other transistors among said transistors in said circuit.
12. The design structure of claim 7 , wherein said global multiplexing block comprises a pair of global series pull-up transistors having a power supply terminal and a terminal interconnected to said global read bit line, a first transistor of said pair of global series pull-up transistors having a gate for receiving a global pre-charge signal and a second transistor of said pair of global series pull-up transistors having a gate for receiving said SLEEP signal.
13. The design structure of claim 7 , wherein said design structure comprises a netlist.
14. The design structure of claim 7 , wherein said design structure resides on storage medium as a data format used for exchange of layout data of integrated circuits.
15. A method comprising:
providing a memory circuit, said memory circuit comprising:
a global read bit line;
a global read bit line latch;
a plurality of sub-arrays, each of said sub-arrays comprising:
a first local read bit line;
a first local write bit line;
a first plurality of memory cells interconnected with said first local read bit line and said first local write bit line, said first local read bit line being decoupled from said first local write bit line;
a second local read bit line;
a second local write bit line;
a second plurality of memory cells interconnected with said second local read bit line and said second local write bit line, said second local read bit line being decoupled from said second local write bit line; and
a local multiplexing block interconnected with said first and second local read bit lines and configured to ground said first and second local read bit lines upon assertion of a SLEEP signal and to selectively interconnect said local read bit lines to said global read bit line; and
a global multiplexing block interconnected with said global read bit line and configured to maintain said global read bit line in a substantially discharged state upon assertion of said SLEEP signal and to interconnect said global read bit line to said global read bit line latch; and
asserting said SLEEP signal to cause (i) said grounding of said first and second local read bit lines and (ii) said global read bit line to be maintained in said substantially discharged state;
whereby stand-by power consumption is reduced in said circuit.
16. The method of claim 15 , wherein each of said local multiplexing blocks comprises:
a first pair of series pull-up transistors having a power supply terminal and a terminal interconnected to said first local read bit line, a first transistor of said first pair of series pull-up transistors having a gate for receiving a local pre-charge signal and a second transistor of said first pair of series pull-up transistors having a gate for receiving said SLEEP signal;
a second pair of series pull-up transistors having a power supply terminal and a terminal interconnected to said second local read bit line, a first transistor of said second pair of series pull-up transistors having a gate for receiving a local pre-charge signal and a second transistor of said second pair of series pull-up transistors having a gate for receiving said SLEEP signal;
a first pull-down transistor having a first terminal interconnected to said first local read bit line, a grounded second terminal, and a gate for receiving said SLEEP signal;
a second pull-down transistor having a first terminal interconnected to said second local read bit line, a grounded second terminal, and a gate for receiving said SLEEP signal;
a NAND gate having first and second inputs interconnected, respectively, with said first and second local read bit lines, and having an output; and
a third pull-down transistor having a first terminal coupled to said global read bit line, a grounded second terminal, and a gate coupled to said output of said NAND gate; and
wherein said step of asserting said SLEEP signal comprises applying said SLEEP signal to:
said gates of said first and second pull-down transistors;
said gate of said second transistor of said first pair of series pull-up transistors; and
said gate of said second transistor of said second pair of series pull-up transistors.
17. The method of claim 16 , wherein said global multiplexing block comprises a pair of global series pull-up transistors having a power supply terminal and a terminal interconnected to said global read bit line, a first transistor of said pair of global series pull-up transistors having a gate for receiving a global pre-charge signal and a second transistor of said pair of global series pull-up transistors having a gate for receiving said SLEEP signal; and
wherein said step of asserting said SLEEP signal further comprises applying said SLEEP signal to said gate of said second transistor of said pair of global series pull-up transistors.