Pipelining an asynchronous memory reusing a sense amp and an output latch

Patent metadata

Field	Value
Publication number	US-9548089-B2
Application number	US-201514742706-A
Country	US
Kind code	B2
Filing date	Jun 18, 2015
Priority date	Apr 1, 2015
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

An asynchronous memory includes a memory array, a sense amplifier, an output latch, and a controller. In response to a clock signal from an external circuit requesting a read operation, the controller provides the clock signal to the memory array to read data, and controls the sense amplifier and the output latch to provide the functionality of a flip-flop master and slave so that the read operation delay through the output latch to the external circuit is removed from a first read cycle of two sequential read cycles.

First claim

What is claimed is:

1. A circuit comprising:
a memory array configured to store data;
a sense amplifier coupled to the memory array;
an output latch coupled to the sense amplifier; and
a controller configured to:
provide a first clock signal to the memory array, an enable signal to the sense amplifier, and a latch signal to the output latch, the controller configured to generate the first clock signal based on a second clock signal received from an external circuit;
perform a first read operation to read a first data stored in the memory array in a first clock cycle of the first clock signal;
drive the first clock signal to a first state and then drive the first clock signal to a second state in the first clock cycle of the first clock signal, the first clock signal driven to the first state to begin the first read operation;
drive the latch signal from a first state to a second state and then drive the enable signal from a second state to a first state in the first clock cycle of the first clock signal, the enable signal driven to the first state to cause the sense amplifier to hold the first data;
drive the latch signal from the second state to the first state and then drive the enable signal from the first state to the second state in a second clock cycle of the first clock signal, the second clock cycle of the first clock signal immediately following the first clock cycle of the first clock signal, wherein the latch signal is driven to the first state to cause the output latch to latch the first data; and
provide the first data to the external circuit in the second clock cycle of the first clock signal.

2. The circuit of claim 1 , wherein
the first clock signal is HIGH when in the first state and is LOW when in the second state;
the enable signal is HIGH when in the first state and is LOW when in the second state; and
the latch signal is HIGH when in the first state and is LOW when in the second state.

3. The circuit of claim 1 , wherein the controller is further configured to:
drive the first clock signal to the first state in the second clock cycle of the first clock signal to begin a second read operation to read a second data from the memory array; and
drive the latch signal from the first state to the second state and then drive the enable signal from the second state to the first state in the second clock cycle of the first clock signal, wherein the enable signal is driven from the second state to the first state to cause the sense amplifier to hold the second data.

4. The circuit of claim 3 , wherein
the first clock signal is HIGH when in the first state and is LOW when in the second state;
the enable signal is HIGH when in the first state and is LOW when in the second state; and
the latch signal is HIGH when in the first state and is LOW when in the second state.

5. The circuit of claim 3 , wherein the controller is further configured to drive the latch signal from the second state to the first state and then drive the enable signal from the first state to the second state in a third clock cycle of the first clock signal, wherein the third clock cycle of the first clock signal immediately follows the second clock cycle of the first clock signal, and wherein the latch signal is driven to the first state to cause the output latch to latch the second data.

6. The circuit of claim 5 , wherein the controller is further configured to:
provide the second data to the external circuit in the third clock cycle of the first clock signal.

7. A method to read a memory array, comprising:
generating a first clock signal to provide at least a first clock cycle and a second clock cycle, wherein the first clock signal is generated based on a second clock signal received from an external circuit;
reading a first data from the memory array in the first clock cycle;
enabling a sense amplifier in the first clock cycle to hold the first data;
disabling an output latch in the first clock cycle before enabling the sense amplifier in the first clock cycle;
disabling the sense amplifier in the second clock cycle, the second clock cycle immediately following the first clock cycle;
enabling the output latch in the second clock cycle to latch the first data before disabling the sense amplifier in the second clock cycle; and
providing the first data to the external circuit in the second clock cycle.

8. The method of claim 7 , further comprising:
reading a second data from the memory array in the second clock cycle;
enabling the sense amplifier in the second clock cycle to hold the second data; and
disabling the output latch in the second clock cycle before enabling the sense amplifier in the second clock cycle.

9. The method of claim 8 , further comprising:
disabling the sense amplifier in a third clock cycle, the third clock cycle immediately following the second clock cycle; and
enabling the output latch in the third clock cycle to latch the second data before disabling the sense amplifier in the third clock cycle.

10. The method of claim 9 , further comprising:
providing the second data to the external circuit in the third clock cycle.

11. An apparatus configured to read a memory array, the apparatus comprising:
means for generating a first clock signal to provide at least a first clock cycle and a second clock cycle, wherein the first clock signal is generated based on a second clock signal received from an external circuit;
means for reading from the memory array a first data in the first clock cycle;
means for enabling a sense amplifier in the first clock cycle to hold the first data;
means for disabling an output latch in the first clock cycle before enabling the sense amplifier in the first clock cycle;
means for disabling the sense amplifier in the second clock cycle, the second clock cycle immediately following the first clock cycle;
means for enabling the output latch in the second clock cycle to latch the first data before disabling the sense amplifier in the second clock cycle; and
means for providing the first data to the external circuit in the second clock cycle.

12. The apparatus of claim 11 , further comprising:
means for reading from the memory array a second data in the second clock cycle;
means for enabling the sense amplifier in the second clock cycle to hold the second data; and
means for disabling the output latch in the second clock cycle before enabling the sense amplifier in the second clock cycle.

13. The apparatus of claim 12 , further comprising:
means for disabling the sense amplifier in a third clock cycle, the third clock cycle immediately following the second clock cycle; and
means for enabling the output latch in the third clock cycle to latch the second data before disabling the sense amplifier in the third clock cycle.

14. The apparatus of claim 13 , further comprising:
means for providing the second data to the external circuit in the third clock cycle.

15. A circuit comprising:
a memory array configured to store data;
a sense amplifier coupled to the memory array;
an output latch coupled to the sense amplifier; and
a controller configured to:
generate a first clock signal to provide at least a first clock cycle and a second clock cycle to immediately follow the first clock cycle, wherein the controller is configured to generate the first clock signal based on a second clock signal received from an external circuit;
read a first data from the memory array in the first clock cycle;
disable the output latch and subsequently enable the sense amplifier in the first clock cycle, the sense amplifier enabled in the first cl

Assignees

• Qualcomm Inc

Inventors

• Liles Stephen Edward
• Maurya Satendra Kumar
• Garg Kunal
• Chai Chiaming
• Shah Chintan

Classifications

• G11C7/065 Primary

  Differential amplifiers of latching type · CPC title

• G11C7/1039

  using pipelining techniques, i.e. using latches between functional memory parts, e.g. row/column decoders, I/O buffers, sense amplifiers · CPC title

• G11C7/1066

  Output synchronization · CPC title

• G11C7/106

  Data output latches · CPC title

• G11C7/06

  Sense amplifiers; Associated circuits {, e.g. timing or triggering circuits} · CPC title