Low power asynchronous sense amp
View Patent ↗A memory sense amplifier includes an output and a complement output. The sense amplifier is configured such that a memory cell driving the bit line low enables latching of the bit line low by enabling pull-up of the complement output, and the memory cell driving the complement bit line low enables latching of the complement bit line low by enabling pull-up of the output.
1. A sense amplifier circuit comprising:
first pull-up and pull-down stages coupled to a bit line;
second pull-up and pull-down stages coupled to a complementary bit line;
a first latch circuit output tapped between the first pull-up and pull-down stages, the first output coupled to disable the second pull-up stage if the first output is asserted; and
a second latch circuit output tapped between the second pull-up and pull-down stages, the second circuit output coupled to disable the first pull-up stage if the second output is asserted.
2. The circuit of claim 1 , including;
a first non-clocked hold circuit coupled to the bit line; and
a second non-clocked hold circuit coupled to the complement bit line.
3. The circuit of claim 1 , wherein each pull-down stage further comprises:
at least one pull-down transistor.
4. The circuit of claim 1 , wherein each pull-up stage further comprises:
at least a pair of PFETs coupled in series.
5. The circuit of claim 1 , wherein the first pull-up stage further comprises:
a first transistor gate-coupled to the second output, and a second transistor gate-coupled to the complement bit line.
6. The circuit of claim 1 , wherein the second pull-up stage further comprises:
a first transistor gate-coupled to the first output, and a second transistor gate-coupled to the bit line.
7. The circuit of claim 1 , further comprising:
the first output further coupled to pull the complement bit line low if asserted.
8. The circuit of claim 1 , further comprising:
the second output further coupled to pull the bit line low if asserted.
9. A memory sense amplifier comprising:
an output and a complement output, the sense amplifier configured such that pre-charging a bit line and a complement bit line activates hold circuits for the bit line and complement bit line, holding both in a charged state, and driving both the output and the complement output to the same known state, and further configured such that a memory call driving the bit line low enables latching of the bit line low by enabling pull-up of the complement output, the sense amplifier further configured such that the memory cell driving the complement bit line low enables latching of the complement bit line low by enabling pull-up of the output.
10. The memory sense amplifier of claim 9 , wherein the hold circuits for the bit line and complement bit line further comprise:
a non-clocked combination of at least one buffer and at least one transistor.
11. The memory sense amplifier of claim 9 , wherein enabling latching of the bit line low by enabling pull-up of the complement output further comprises:
activating at least one bit line pull-down transistor and activating at least one complement output pull-up transistor.
12. The memory sense amplifier of claim 9 , wherein enabling latching of the complement bit line low by enabling pull-up of the output further comprises:
activating at least one complement bit line pull-down transistor and activating at least one output pull-up transistor.
13. The memory sense amplifier of claim 11 further comprising at least one transistor in series with the bit line pull-down transistor, to disable latching of the bit line during pre-charge of the bit line.
14. The memory sense amplifier of claim 12 further comprising at least one transistor in series with the complement bit line pull-down transistor, to disable latching of the complement bit line during pre-charge of the complement bit line.
15. A memory sense amplifier circuit comprising:
first pull-up and pull-down stages coupled to a memory bit line;
second pull-up and pull-down stages coupled to a complementary memory bit line;
a first latch circuit output tapped between the first pull-up and pull-down stages, the first output coupled to disable the second pull-up stage and to enable the first pull-down stage if the first output is asserted; and
a second latch circuit output tapped between the second pull-up and pull-down stages, the second circuit output coupled to disable the first pull-up stage and to enable the second pull-down stage if the second output is asserted.
16. The memory sense amplifier circuit of claim 15 , including
a first hold circuit coupled to the memory bit line; and
a second hold circuit coupled to the complement memory bit line.
17. The circuit of claim 15 , wherein:
the first pull-up stage comprises:
a first transistor gate-coupled to the second latch circuit output, and a second transistor in series with the first transistor and gate coupled to the complement bit line; and
the second pull-up stage comprises:
a first transistor gate-coupled to the first latch circuit output, and a second transistor in series with the first transistor and gate-coupled to the bit line.
18. The circuit of claim 15 , wherein the first pull-down stage comprises a transistor gate-coupled to the first latch circuit output and the second pull-down stage comprises a transistor gate-coupled to the second latch circuit output.