95 results about "Static noise margin" patented technology

A substrate potential setting circuits are provided which control substrate potentials in units of columns of a memory cell array at least in data writing. Upon data writing, the potential of the substrate region of memory cell transistors on a selected column is changed to reduce the data holding characteristics (static noise margin) to ensure high-speed data writing to the memory cells. Data writing is performed at high speed without impairing stability of data retention.

Intrinsic variations and challenging leakage control in current bulk-Si MOSFETs force undesired tradeoffs to be made and limit the scaling of SRAM circuits. Circuits and mechanisms are taught herein which improve leakage and noise margin in SRAM cells, such as those comprising either six-transistor (6-T) SRAM cell designs, or four-transistor (4-T) SRAM cell designs. The inventive SRAM cells utilize a feedback means coupling a portion of the storage node to a back-gate of an access transistor. Preferably feedback is coupled in this manner to both access transistors. SRAM cells designed with this built-in feedback achieve significant improvements in cell static noise margin (SNM) without area penalty. Use of the feedback scheme also results in the creation of a practical 4-T FinFET-based SRAM cell that achieves sub-100 pA per-cell standby current and offers similar improvements in SNM as the 6-T cell with feedback.

The present invention provides a power gating structure having data retention and intermediate modes and able to operate under multiple modes. A conventional power gating structure has only turn-on and turn-off functions, and is used to suppress a leakage current problem which has become more and more serious in advance manufacture processes, under a turn-off mode. However, in a memory circuit, such as latch, register and SRAM, when the power gate is turned off, a new power gating structure is required for data retention. The power gating structure of the present invention can be set into one of 4 different operational modes: a data retention mode for maintaining the static noise margin of the memory, an intermediate mode for reducing the interference on ground and power levels, an active mode used when the circuit operates in normal condition, and a standby mode used when the circuit does not operate.

A Schmitt Trigger (ST) based, fully differential, 10-transistor (10T) SRAM (Static Random Access Memory) bitcell suitable for sub-threshold operation. The Schmitt trigger based bitcell achieves 1.56× higher read static noise margin (SNM) (V_DD=400 mV) compared to a conventional 6T cell. The robust Schmitt trigger based memory cell exhibits built-in process variation tolerance that gives tight SNM distribution across the process corners. It utilizes fully differential operation and hence does not require any architectural changes from the present 6T architecture. The 10T bitcell has two cross-coupled Schmitt trigger inverters which each consist of four transistors, including a PMOS transistor and two NMOS transistors in series, and an NMOS feedback transistor which is connected between the inverter output and the junction between the series-connected NMOS transistors. Each inverter has one associated NMOS access transistor.

A three-dimensional (3D) memory cell separation among 3D integrated circuit (IC) (3DIC) tiers is disclosed. Related 3DICs, 3DIC processor cores, and methods are also disclosed. In embodiments disclosed herein, memory read access ports of a memory block are separated from a memory cell in different tiers of a 3DIC. 3DICs achieve higher device packing density, lower interconnect delays, and lower costs. In this manner, different supply voltages can be provided for the read access ports and the memory cell to be able to lower supply voltage for the read access ports. Static noise margins and read/write noise margins in the memory cell may be provided as a result. Providing multiple power supply rails inside a non-separated memory block that increases area can also be avoided.

An SRAM memory cell structure utilizing a read driver transistor for isolating the read current from the latch nodes of the cell during read operations and a column select write transistor for selection of a single cell during write operations, and a method of operating the same is discussed. The SRAM memory cell structure (single-ended or differential cell) allows independent optimization of the static noise margin, trip voltage, and read current, thereby avoiding some of the static noise margin and trip voltage problems of conventional SRAM cells (e.g., a conventional 6T differential cell). In one implementation, the SRAM memory cell comprises a 7T single-ended cell including first and second cross-coupled inverters, having a first and second latch nodes, respectively. The cell further comprises a first write pass transistor connected between the first latch node of the first inverter and a first pass node, and a first wordline pass transistor connected between the first pass node and a first bitline. The cell also includes a first read driver connected between the first pass node and a source potential, and a control terminal of the first read driver connected to the second latch node of the second inverter. Beneficially, the read current conducts through the first read driver to avoid upsetting the data state at the latch node. Further, a differential 10T SRAM memory cell for coupling to a complimentary pair of bitlines is discussed, having all the elements mentioned above used in the exemplary 7T cell.

A method of reading stored data in a semiconductor memory device able to suppress the reduction in the static noise margin accompanying a voltage drop of a power supply voltage, and able to improve the degree of integration of the circuit, that is, a method of reading stored data of a semiconductor memory device which has a first storage node and a second storage node, a first transistor having a control terminal connected to the first storage node and having a pair of input/output terminals connected between the second storage node and a reference potential, a second transistor having a control terminal connected to the second storage node and having a pair of input/output terminals connected between the first storage node and the reference potential, a third transistor having a pair of input/output terminals connected between the first storage node and a first bit line and having a control terminal connected to a word line, and a fourth transistor having a pair of input/output terminals connected between the second storage node and a second bit line and having a control terminal connected to the word line, comprising the steps of applying a first voltage to the first bit line and the second bit line in a period for holding the stored data, and activating the word line and applying a second voltage higher than the first voltage to the first bit line and the second bit line at the time of reading the stored data, and a semiconductor memory device using the same.

A static random access memory (14) has a normal mode of operation and a low voltage mode of operation. A memory array (15) includes memory cells (16) coupled to a first power supply node (V_DD) for receiving a power supply voltage. A plurality of word line drivers is coupled to word lines of the memory array (15) and to a second power supply node (37). A word line driver voltage reduction circuit (36) has an input coupled to the first power supply node (V_DD) and an output coupled to the second power supply node (37) for reducing a voltage on the output in relation to a voltage on the input in response to a low power supply voltage signal, and thus improving a static noise margin of the memory cells (16).

A set of memory cell test structures and a method are disclosed for assessment of the static noise margin (SNM) of a memory cell or an array of such cells, for example, of SRAM cells of an integrated circuit device, using discrete point measurement structures provided either on-chip or within the scribe lines. In one embodiment, the set of memory structures comprises first and second test structures, individually comprising a memory cell, having one or more left and right half-bit test structures having hard-wired connections between select nodes of each memory cell half-bit and one or more voltage supplies. The half-bits of the first test structure are configured for measuring respective left and right standby SNM values, and the half-bits of the second test structure are configured for measuring respective left and right cell ratio values at respective output nodes of the structures, using applied supply voltages for on-chip assessment of the static noise margin of the memory cells. The method applies the supply voltages to select nodes of the test structures, measures left and right standby SNM values at a first test structure, measures left and right cell ratio values at a second test structure, determines a first difference between the left half-bit standby SNM value and the right half-bit cell ratio value, determines a second difference between the right half-bit standby SNM value and the left half-bit cell ratio value, and determines a smaller one of the first and second difference values proportional to an SNM value of the cell.

A static random access memory (“SRAM”) has a plurality of SRAM cells connected to a word line. A static noise margin (“SNM”) detector controls a pull-down transistor that selectively couples the word line to a ground path. The SNM detector is configured to produce a first output signal in response to a SNM event that couples the word line to the ground path, and otherwise produces a second output signal that de-couples the word line from the ground path.

The invention discloses a double-bit-line sub-threshold storage unit circuit which employs double-end read-write operation. The double-bit-line sub-threshold storage unit circuit comprises a first phase inverter and a second phase inverter, wherein the two phase inverters are connected to form a cross coupling; and by employing a double-bit-line structure of separating read bit lines from write bit lines, two storage nodes of the cross coupling are respectively connected to two write bit lines through an N-channel metal oxide semiconductor (NMOS) tube, and another two storage nodes of the cross coupling are respectively connected to two read bit lines through the NMOS tube and a P-channel metal oxide semiconductor (PMOS) tube. The double-bit-line sub-threshold storage unit circuit has the advantages that: by employing a PMOS substrate regulation technology, substrate ends of all PMOS tubes are connected to gate ends, so on the premise that additional management power consumption is not improved and the performance is not reduced, the energy consumption of dynamic operation and the leakage power consumption of static operation of a system can be reduced simultaneously, the static noise margin of a storage unit is improved, and the performance of the system is optimized.