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What is CMOS Digital Electronics Technology C MOS
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What is CMOS Digital Electronics Technology C MOS
C-MOS or CMOS stands for complementary metal-oxide-semiconductor, it is a technology for constructing integrated circuits widely used in microprocessors, microcontrollers, and other Digital Memory RAM circuits. CMOS technology is also used for several analog circuits such as image sensors, data converters and transceivers for many types of communication. Created by Frank Wanlassem 1963, CMOS is also sometimes referred to as complementary-symmetry metal-oxide-c or COS-MOS semiconductor. The words "complementary-symmetry" refer to the fact that the typical digital design style with CMOS uses complementary and symmetrical pairs of field effect transistors (Field Effect Transistors - FET) p-type or n semiconductor oxide metal (MOSFETs) for logic functions, as shown in figure below.
What is CMOS
Existem features relevant and important in CMOS devices such as low immunity to static and low energy consumption. As one of the transistor pair is always turned off, the combinação em series consumes significant energy only momentarily during the alternation between connected and disconnected states (on / off). Consequentemente, CMOS devices NON produzem much heat as other forms of rationale, such as TTL, which typically consume current even quando em home.
The também CMOS technology enables high-density u funções em um logic single chip. It was mainly for this race that has become the most used technology to be applied em VLSI (Very-large-scale Integration), is the Process of criação integrated circuit through the combinação of milhares transistor em um single chip.
Family CMOS integrated circuits - 4000 and 74C
The 4000 series is a family of CMOS integrated circuits that implement a variety of logic functions that are still in use today . They were introduced by RCA as CD4000 series COS / MOS in the year 1968 as a lower power and a more versatile alternative to the 7400 series TTL . This CMOS series have the advantage of lower power consumption and wide range of supply voltages of 3 V to 15 V . However its speed is slower , 1 MHz , compared to the 10 MHz bipolar TTL , this limits their applications to projects of low speed or static .
Characteristics CMOS
Supply ( Vdd ) : as the supply voltage , this family allows for series 4000 and 74C operating in the range of 3V to 15V , for the HC version of 2V to 6V and HCT of 4.5 V to 5.5 V. For series low voltage , the range is from 1V to 3.6V and 1.2V to LV to 3.3 V , typical voltage of various current systems .
Integrated circuits CMOS Whenever there unused entries or entire unused ports , it is critical that all inputs are grounded or connected to + VDC , we have to take this step due to
large impedance inputs 10 ¹ ² Ω , and any stray current or arising from noise in the input lead to a considerable increase of tension.
The CMOS sub-families are in the table below.
HC - High Speed CMOS - CMOS High Speed
HCT - High Speed CMOS with TTL inputs - High Speed CMOS with TTL inputs
AC - Advanced CMOS - CMOS Advanced High-speed version
ACT - Advanced CMOS with TTL inputs - Advanced CMOS inputs with TTL-version
BCT - BiCMOS Technology - Technology BiCMOS (Bipolar / CMOS)
ABT - Advanced BiCMOS Technology - Advanced BiCMOS Technology
LVT - Low Voltage Technology - Technology Low Voltage
New CMOS technology
New manufacturing technologies largely overcame the speed problems , while maintaining compatibility with most circuit designs . Although all semiconductors can be damaged by electrostatic discharge , high impedance CMOS inputs makes them more susceptible than bipolar transistors based , TTL . Eventually , the advantages of CMOS (especially the later series such as 74HC ) (High- speed CMOS ) surpassed the older TTL chips . The 4000 series is still widely available , but perhaps less important than it was two decades ago .
The 4000 series was expanded in the late 1970s and 1980s to include new functions , or were better versions , most of these newer chips were given the 4500 series, but are still considered by engineers as part of the series of 4000 . During the 1990s , some manufacturers such as Texas Instruments , merged its online its latest technology called HCMOS emerging devices like 74HCT4060 , having the same features of a 4060 but with greater speed.
CMOS integrated circuit
Lets take the example of 4011, an integrated circuit CMOS 4000 series, which contains four independent NAND gates of two inputs. The pinout see below. This chip is different in pinout to the TTL 7400, but it can fulfill its function if done modifications pins.
In 4011 pinout can see that the 7 pin is the negative supply and the 14 pin is the positive supply.
Since pins 1 and 2, 5, 6, 8, 9, 12 and 13 are input ports and pins 3, 4, 10, 11 are output ports. To get a better idea the image below shows the relationship without taking into account the position of the pins on the chip.
The truth table is a mathematical table that logic, it consists of a column for each variable (A and B in our case only two inputs) input, and a final column for all possible outcomes of the logic operation, output or output and in our case Q. Each row of the truth table contains one possible configuration of the input variables, and the result of the operation of such values.
H = HIGH = 1 high = 5 Volts
L = LOW = 0 = 0 = Low Volts
The truth table for the four doors 4011 is shown below.
A B Q
0 0 1
0 1 1
1 0 1
1 1 0
Advantages and disadvantages of CMOS integrated circuits
In comparison with other digital technologies and CMOS logic families have advantages and disadvantages, see below major.
Advantages
manufacturing is simpler and less costly;
does not use resistors;
has a high input impedance;
Disadvantages
fragility static electricity
delay time;
low-speed operation;
Other members of logic families:
RTL - resistor-transistor logic - Obsolete Technology
DTL - Diode-Transistor Logic - Obsolete Technology
DCTL - Transistor Logic Direct coupling
TTL - Transistor-Transistor Logic
ECL - Emitter-coupled logic
MOS - Metal Oxide Semiconductor:
PMOS - Logic of p-channel MOSFETs - Obsolete Technology
NMOS - Logic n-channel MOSFETs
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