Patent Application
20090003111
With reductions in supply voltages being employed in products today, lit may be more difficult to distinguish stored data from noise. Noise may be generated by semiconductor devices themselves, or may be radiation induced such as noise measured as Soft Error Rate (SER) in an apparatus. There is a need in semiconductor information storage apparatuses for improving reliability of operation in the presence of noise.
The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate corresponding or analogous elements.
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.
Some portions of the detailed description that follows are presented in terms of algorithms and symbolic representations of operations on data bits or binary digital signals within a computer memory. These algorithmic descriptions and representations may be the techniques used by those skilled in the data processing arts to convey the substance of their work to others skilled in the art.
Embodiments of the present invention may include apparatuses for performing the operations herein. An apparatus may be specially constructed for the desired purposes, or it may comprise a general purpose computing device selectively activated or reconfigured by a program stored in the device. Such a program may be stored on a storage medium, such as, but not limited to, any type of disk including floppy disks, optical disks, compact disc read only memories (CD-ROMs), magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs), electrically programmable read-only memories (EPROMs), electrically erasable and programmable read only memories (EEPROMs), magnetic or optical cards, or any other type of media suitable for storing electronic instructions, and capable of being coupled to a system bus for a computing device.
The processes and displays presented herein are not inherently related to any particular computing device or other apparatus. Various general purpose systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct a more specialized apparatus to perform the desired method. The desired structure for a variety of these systems will appear from the description below. In addition, embodiments of the present invention are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the invention as described herein. In addition, it should be understood that operations, capabilities, and features described herein may be implemented with any combination of hardware (discrete or integrated circuits) and software.
Use of the terms “coupled” and “connected”, along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” my be used to indicated that two or more elements are in either direct or indirect (with other intervening elements between them) physical or electrical contact with each other, and/or that the two or more elements co-operate or interact with each other (e.g. as in a cause and effect relationship).
Resistive element 154 may be embodied in a discrete resistive element in a circuit path 160 coupling drains 118, 138. Resistive element 156 may be embodied in a discrete resistive element in a circuit path 162 coupling drains 128, 148. Alternatively, resistive elements 154, 156 may be embodied in resistive material (i.e., higher resistance than may be employed in coupling other elements of apparatus 100) employed in fashioning circuit paths 160, 162 for at least a portion of each circuit path 160, 162. By way of example and not by way of limitation, such a higher resistive material may be embodied in gate material, or metal interconnect of the sort used for fashioning gates 116, 126, 136, 146. Resistive elements 154, 156 may present sufficient resistance to cooperate with capacitance present in apparatus 100 to establish RC (Resistive-Capacitive) time constants appropriate for permitting apparatus 100 to accommodate a noise signal having a predetermined duration without losing stored data or information in apparatus 100. Noise signals typically may be presented as sharp, short duration spiked signals having a shorter duration than data signals or other signals in an apparatus. Introducing or increasing an RC time constant into operation of an apparatus may cause the apparatus to react more slowly to changes in signals than would be the case with no RC time constant or a lower RC time constant. Such a slower reaction may cause an apparatus to “overlook”, not react to or otherwise accommodate a noise signal without disrupting operation of the apparatus, such as by way of example and not by way of limitation, losing stored information.
One measure of noise may be expressed as SER (Soft Error Rate), a measure known by one skilled in the art of semiconductor design. Resistive elements 154, 156 may be configured to cooperate with capacitance in apparatus 100 to meet or exceed a predetermined SER measure. Capacitance cooperating with resistive elements 154, 156 to establish a desired RC time constant may be found in transistor devices 110, 120, 130, 140, in connections among portions or elements of apparatus 100 (e.g., in circuit paths 160, 162) or elsewhere in apparatus 100.
Resistive elements 254, 256, 258, 259 may be embodied in discrete resistive elements in circuit paths 260, 262. Alternatively, resistive elements 254, 256, 258, 259 may be embodied in resistive material (i.e., higher resistance than may be employed in coupling other elements of apparatus 200) employed in fashioning circuit paths 260, 262 for at least a portion of each circuit path 260, 262. By way of example and not by way of limitation, such a higher resistive material may be embodied in gate material, or metal interconnect of the sort used for fashioning gates 216, 226, 236, 246. Resistive elements 254, 256, 258, 259 may present sufficient resistance to cooperate with capacitance present in apparatus 200 to establish RC (Resistive-Capacitive) time constants appropriate for permitting apparatus 200 to accommodate a noise signal having a predetermined duration without losing stored data or information in apparatus 200.
Resistive elements 354, 356, 370, 372, 374, 376 may be embodied in discrete resistive elements in circuit paths 360, 362, 364, 366, 368, 369. Alternatively, resistive elements 354, 356, 370, 372, 374, 376 may be embodied in higher resistance material (i.e., higher resistance than may be employed in coupling other elements of apparatus 300) employed in fashioning circuit paths 360, 362, 364, 366, 368, 369 for at least a portion of each circuit path 360, 362, 364, 366, 368, 369. By way of example and not by way of limitation, such a resistive material may be embodied in gate material, or metal interconnect of the sort used for fashioning gates 316, 326, 336, 346. Resistive elements 354, 356, 370, 372, 374, 376 may present sufficient resistance to cooperate with capacitance present in apparatus 300 to establish RC (Resistive-Capacitive) time constants appropriate for permitting apparatus 300 to accommodate a noise signal having a predetermined duration without losing stored data or information in apparatus 300.
Resistive element 454 may be embodied in a discrete resistive element in a circuit path 460 coupling drains 418, 438. Resistive element 456 may be embodied in a discrete resistive element in a circuit path 462 coupling drains 428, 448. Alternatively, resistive elements 454, 456 may be embodied in higher resistance material (i.e., higher resistance than may be employed in coupling other elements of apparatus 400) employed in fashioning circuit paths 460, 462 for at least a portion of each circuit path 460, 462. By way of example and not by way of limitation, such a higher resistive material may be embodied in gate material of the sort used for fashioning gates 416, 426, 436, 446. Resistive elements 454, 456 may present sufficient resistance to cooperate with capacitance present in apparatus 400 to establish RC (Resistive-Capacitive) time constants appropriate for permitting apparatus 400 to accommodate a noise signal having a predetermined duration without losing stored data or information in apparatus 400.
Apparatus 400 may also include an access device 480 coupled for providing data or information for storing in apparatus 400 from a locus 481 to a circuit locus 437 in response to a gating WRITE command applied at a gate 482. Access device 480 may also read stored information to locus 481 from apparatus 400 in response to a gating READ command applied at gate 482. Apparatus 400 may also include an access device 490 coupled for providing data or information for storing in apparatus 400 from a locus 491 to a circuit locus 449 in response to a gating WRITE command applied at a gate 492. Access device 490 may also read stored information to locus 491 from apparatus 400 in response to a gating READ command applied at gate 492. Access devices 480, 490 may be coupled with apparatus 400 at a lower potential end of resistive elements 454, 456 so that SER or noise contribution by access devices 480, 490 may be minimized. Alternately, access devices 480, 490 may be embodied in PMOS transistor devices and coupled at loci substantially adjacent to 418, 428 (not shown) as may be understood by one skilled in the art of storage unit circuitry design.
Embodiments of the invention may provide noise suppression, improved stability and improved reliability by providing a filtering effect using an RC time constant. Noise generated at a particular drain node may be attenuated when the noise arrives at the neighboring drain node. Embodiments of the invention may also provide noise suppression, improved stability and improved reliability by providing a voltage-division effect by which DC (Direct Current) noise caused, by way of example and not by way of limitation, because of a defective component may have reduced impact at a neighboring node. This voltage-division effect may reduce lower useful limits of supply voltage VCC, by way of example and not by way of limitation, because process variations and defects in resistors have mainly DC impact.
While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
