Texas Instruments Corporation

Lakshmikantha V Holla

Vinod J Menezes

Michael Patrick Clinton

Theodore Warren Houston

Parvinder Kumar Rana

Thomas J Aton

Xiaowei Deng

Wah Kit Loh

Sharad Kumar Gupta

Bryan David Sheffield

Manish Chandra Joshi

Suresh Balasubramanian

Santhosh Narayanaswamy

Steve Prins

Dharaneedharan S

A memory circuit includes at least one bit cell that receives a word line, complementary bit lines and an array supply voltage and a word line suppression circuit. The word line suppression circuit includes two PFETs with their drains connected to the word line and their sources connected to the array supply voltage and an NFET with its source connected to ground and its drain connected to the word line. The NFET is inactivated before the PFETs are activated. One of the PFETs is activated before the other PFET is activated so as to control the slew rate of the word line and improve the static noise margin of the at least one bit cell.

Read assist for an SRAM using a word line suppression circuit

A memory circuit includes a bit cell that receives a word line, complementary bit lines and an array supply voltage; a word line driver coupled to the word line, the word line driver receiving the array supply voltage; and a word line suppression circuit coupled to the word line. The word line suppression circuit includes a diode and a first switch coupled in series and a second switch. The switches are responsive to a control signal. The word line suppression circuit limits a word line voltage to a value lower than the array supply voltage such that the static noise margin (SNM) of the bit cell is increased.

Read assist circuit for an SRAM, including a word line suppression circuit

A semiconductor memory cell includes a set of circuit structures, each having column input/output circuits. The semiconductor memory cell further includes a set of replicas corresponding to the column input/output circuits. The set of replicas are non-functional and fills an empty space next to the column input/output circuits and hence, provides context protection for the column input/output circuits.

Context protection for a column interleaved memory

An 8T memory bit cell receives a clock signal and read and write address signals. A read address latch/clock circuit receives the clock signal and the read address signals and initiates a read operation during a first clock cycle state. A write address flip-flop/clock circuit receives the clock signal and the write address signals and initiates a write operation during a second clock cycle state. An inverter receives and inverts the clock signal and applies the inverted clock signal to the write address flip-flop/clock circuit. The read address latch/clock circuit initiates a read word line precharge operation during the second clock cycle state and a write word line precharge operation during the first clock cycle state. The write address flip-flop/clock circuit may also include a loose self-timer to end a write cycle is a clock signal continues beyond a predetermined time.

High performance two-port SRAM architecture using 8T high performance single port bit cell

A memory circuit includes a bit cell that receives a word line, complementary bit lines and an array supply voltage; a word line driver coupled to the word line, the word line driver receiving one of the array supply voltage and a periphery supply voltage; and a word line suppression circuit coupled to the word line. The word line suppression circuit includes a diode and a switch coupled in series. The switch is responsive to the array supply voltage. The word line suppression circuit limits a word line voltage to a value lower than the array supply voltage such that the static noise margin (SNM) of the bit cell is increased.

Read assist circuit for an SRAM

Bias circuitry for a static random-access memory (SRAM) with a retain-till-accessed (RTA) mode and with write assist bias in a normal operating mode. The memory is constructed of multiple memory array blocks of SRAM cells. Bias devices are associated with each memory array block, and associated with one or more columns. Each bias device includes a diode-connected transistor in parallel with a shorting transistor, between a power supply voltage and a power supply bias node for cells in its column or columns. The shorting transistor receives control signals from control logic so that the diode-connected transistor for each column is shorted during read cycles, and in write cycles in which its columns are not selected; in write cycles in which its columns are selected, the shorting transistor in the bias device is turned off, so that a reduced power supply voltage is applied to the selected column. The shorting transistors for all columns in the block are turned off in the RTA mode. An additional transistor in series with the diode-connected transistor may be included, to enable a floating power supply bias mode.

Combined write assist and retain-till-accessed memory array bias

Memory circuit and a tracking circuit thereof. The tracking circuit includes a dummy bit line (DBL). The tracking circuit further includes a first circuit to discharge the dummy bit line in response to a first signal and a wordline activation signal. The wordline activation signal causes activation of a memory cell. The tracking circuit also includes a second circuit which is responsive to discharge of the dummy bit line to enable access to the memory cell.

Memory circuit and a tracking circuit thereof

A static random access memory (SRAM) and method of evaluating the same for cell stability, write margin, and read current margin. The memory is constructed so that bit line precharge can be disabled, and so that complementary bit lines for each column of cells can float during memory operations. The various tests are performed by precharging the bit lines for a column, then floating the bit lines, and while the bit lines are floating, pulsing the word lines of one or more selected cells to cause the voltage on one of the bit lines to discharge. The discharged bit line voltage is then applied to another cell, which is then read in a normal read operation to determine whether its state changed due to the discharged bit line voltage. The memory can be characterized for cell stability, write margin, and read current margin in this manner; the method can also be adapted into a manufacturing margin screen, or used in failure analysis.

Margin testing of static random access memory cells

A dual port memory implemented using a single port memory core. In an embodiment, the access requests from the two ports are processed in a single memory clock cycle. In one implementation, the access request corresponding to the first port is processed in the high logic state of the memory clock cycle, and the access request corresponding to the second port is processed in the low logic state of the memory clock cycle. A single port memory core may provide multiple memory enable signals and corresponding strobe signals, with each combination of memory enable signal and strobe signal facilitating the memory access request from a corresponding port. An alternative embodiment uses the duration of each clock cycle of the memory clock signal more efficiently by starting the second memory access soon after completion of the first memory access (without waiting for the logic low of memory clock signal).

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Karnataka, India

Lakshmikantha V Holla