Dynamic Shift Registers - Bitsavers - Trailing-Edge

INTRODUCTIONWhile custom and standard MOS have advantagesover each other for specific appl ications, there is ahigh demand for both in today's electronics industry.In most cases, the true test of whether a systemcan most economically be implemented withstandard, custom, or both, can only be determinedafter partitioning. If the quantities in question donot exceed a few hundred units per year, the standardproduct approach is probably the best solution.However, if the total number of units isseveral thousand per year, then customizing isusually the best approach.Custom MOS circu its are designed to do a specificjob. You are not buying capability that is notneeded. The entire chip is devoted to performingyour specific function. Advantages are:1) Fewer Packages2) Lower Power Dissipation3) Smaller P.C. Boards4) Proprietary DesignThese advantages result in lower system costs andprotection of your system design.RESOURCESNational has brought together a group of experiencedcircuit and system designers, separate fromthe standard product group, to offer a customMOS/LSI design service to the industry. This groupis prepared to aid in the logic design of a system,partition the system into feasible LSI circuits ifthe design requires more than one chip, developthe chips, assist the customer in prototype systemcheckout, and put the design into production.National has one of the most advanced IC manufacturingfacilities in the industry. Your customdesign will go through the same production facilitieswhere National's standard MOS products aremanufactured, and thus benefit from our longexperience in MOS processing.As with its bipolar circuits, the key to National'sMOS program is volume production. We are aleading producer of shift registers, read-only memories,and random access memories. I n the lattercategory, National is supplying many second sourceand proprietary static and dynamic RAMs as wellas several advanced large-capacity RAMs. Nationalis also exploring other MOS device applications,such as MAPS (Microprogram mabie ArithmeticProcessor System). This unit contains five LSIchi'ps which, with very few added parts, can comprisea high sophisticated electronic calculator, an"intelligent" computer terminal, or even a lowcostmicroprocessor.National was the first company to offer MOS circuitsthat operate at voltage levels directly compatiblewith TTL. (Previously, level-shifters wereneeded if high-voltage MOS and low-voltage TTLwere to work together). To achieve this so-calledlow-level MOS operation, National pioneered inthe fabrication of circuits made from silicon cutalong the (1-0-0) axis of the crystal. Subsequently,other companies developed bipolar compatibleMOS circuits also. Today, National is investigatinga variety of MOS technologies to determine thebest process to use a specific function. During thepast year, National introduced the silicon gateprocess to the MOS product line; other technologiessuch as ion-implantation, N-channel andCMOS are also being investigated. The companywill use any available technology as a tool toachieve necessary performance for a given function.1-0-0 P-channel metal gate and 1-1-1 silicon selfalignedgate enhancement mode MOS technologiesare presently utilized by National in our standardMOS products. These processes have become industrystandards. All of the P-channel MOS processdevices offer bipolar compatibility.Metal gate devices operate to 3.3 MHz. This technologyis wel.l-suited to random logic and ROMapplications. Higher logic densities and operatingfrequencies approaching 10 MHz can be achievedby using silicon gate technology. This process lendsitself to RAMs, registers, and random logic applications.Static and dynamic logic is available in both metaland silicon gate devices (including ion-implants).In general, less power is dissipated if dynamic logicis employed, which also offers the advantage ofsynchronous operation and eliminates hazards dueto race conditions. In any event, power dissipationof typical LSI functions (up to 1000 gate func·tions) approach 500 mW in devices fabricated witheither metal gate or silicon gate technology.Complementary MOS (CMOS) technology is presentlybeing used on many standard products andwill soon be available for custom products. Structuredlogic, ROMs, RAMs, and registers, designedwith CMOS cannot achieve the density of P­channel MOS. However, quiescent power and dissipationsare less than one microwatt per gate.Operation to 10 MHz can be achieved. One of theadvantages of CMOS is that power dissipation is afunction of frequency, with the DC (quiescent)state consuming the least power.The N-channel process is also undergoing developmentat National. This process allows higher densityand high frequency operation than P-channel.This process is slated for production capabilitybefore June 1972.Ion implantation is a technique that can be appliedto any of the previously mentioned processes. Itallows threshold voltages to be adjusted to a desiredlevel by implanting ions in the gate region. Depletionload devices and large value ohmic resistors arealso being made with ion implantation, whichgreatly improves packing density on LSI chips.DESIGNYour custom design will benefit from National'slongtime experience in the MOS business. Extensiveuse of computer-aided design (CAD) andcomputer simulation programs assure proper operationof your circuit before it goes into production.226