#LOGIC WORLD SERIES#

Has high noise immunity despite fairly low logic levels. Uses transistors to perform logic but biasing is from constant current sources to prevent saturation and allow extremely fast switching. The MOS logic family includes PMOS logic, NMOS logic, complementary MOS (CMOS), and BiCMOS (bipolar CMOS). Uses MOSFETs (metal-oxide-semiconductor field-effect transistors), the basis for most modern logic gates. Often considered to be the father to modern TTL logic. Economical because few other components are needed, but tends to be susceptible to noise because of the lower voltage levels employed. The transistors require carefully controlled parameters. Uses transistors switching between saturated and cutoff states to perform logic. Uses thyristors and SCRs to perform logic operations where high current and or high voltages are required. Performed by semiconductor diodes and small ferrite toroidal cores for moderate speed and moderate power level. Uses neon bulbs or 3 element neon trigger tubes to perform logic. Other types of logic gates include, but are not limited to: Logic familyĮxactly the same as diode logic but can perform at a higher speed. The field-programmable nature of programmable logic devices such as FPGAs has reduced the 'hard' property of hardware it is now possible to change the logic design of a hardware system by reprogramming some of its components, thus allowing the features or function of a hardware implementation of a logic system to be changed. Increasingly, these fixed-function logic gates are being replaced by programmable logic devices, which allow designers to pack many mixed logic gates into a single integrated circuit.

#LOGIC WORLD SERIES#

CMOS uses complementary (both n-channel and p-channel) MOSFET devices to achieve a high speed with low power dissipation.įor small-scale logic, designers now use prefabricated logic gates from families of devices such as the TTL 7400 series by Texas Instruments, the CMOS 4000 series by RCA, and their more recent descendants. To reduce power consumption still further, most contemporary chip implementations of digital systems now use CMOS logic. As integrated circuits became more complex, bipolar transistors were replaced with smaller field-effect transistors ( MOSFETs) see PMOS and NMOS. Transistor–transistor logic (TTL) then supplanted DTL. For higher speed and better density, the resistors used in RTL were replaced by diodes resulting in diode–transistor logic (DTL). RTL gates were used in early integrated circuits. Unlike simple diode logic gates (which do not have a gain element), RTL gates can be cascaded indefinitely to produce more complex logic functions. The simplest family of logic gates uses bipolar transistors, and is called resistor–transistor logic (RTL). In reversible logic, Toffoli or Fredkin gates are used.Ī functionally complete logic system may be composed of relays, valves (vacuum tubes), or transistors. Logic circuits include such devices as multiplexers, registers, arithmetic logic units (ALUs), and computer memory, all the way up through complete microprocessors, which may contain more than 100 million logic gates.Ĭompound logic gates AND-OR-Invert (AOI) and OR-AND-Invert (OAI) are often employed in circuit design because their construction using MOSFETs is simpler and more efficient than the sum of the individual gates. With amplification, logic gates can be cascaded in the same way that Boolean functions can be composed, allowing the construction of a physical model of all of Boolean logic, and therefore, all of the algorithms and mathematics that can be described with Boolean logic. Now, most logic gates are made from MOSFETs (metal–oxide–semiconductor field-effect transistors). Logic gates are primarily implemented using diodes or transistors acting as electronic switches, but can also be constructed using vacuum tubes, electromagnetic relays ( relay logic), fluidic logic, pneumatic logic, optics, molecules, or even mechanical elements. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and unlimited fan-out, or it may refer to a non-ideal physical device (see Ideal and real op-amps for comparison). For discrete TTL logic, see Transistor–transistor logic.Ī logic gate is an idealized or physical device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. For discrete circuitry, see Discrete circuit.

Logic world