Can Your Dog Ger Oral Herpies

Types Types Ciruit

System radio am / fm

such an integrated combines most of the circuits needed for a complete system receiving radio am / fm. internal blocks that contained in the system include a power amplifier, a converter am (mixer and local oscillator), the stage of fi am, the detector stage fi fm and fm detector. necessary external components such as resistors, inductors and resistors to make fully functional receiver. these external components identifies some of the functional characteristics of the system, such as the bandwidth and gain. further external components needed to build the tank circuits necessary for the tuning stages of fi. functions can also be included in the integrated power supply is regulated, the output meter and audio mute.

reception system am

as shown in the figure below (fig. 5), all active components of a typical AM receiver are integrated into a single CI. only resonance networks must be available abroad. This integrated circuit includes the RF converter, IF amplifier, the detector circuit and automatic gain control (AGC), the integrated zener diode controller and audio preamp stage. in some integrated reception systems am also including rf amplifier, excluding the tuning meter or audio preamplifier.

Appliance Timer control

timers control but differ in their flexibility of application, the timer is typical, as the integrated circuit shown in following figure (Fig. 6), can be used with both 50 lines of 60 hz working both on an hourly basis of twelve and twenty-four hours. if using a power line, you must have an external clock input. external control terminals are used to initialize the minutes and hours and start or stop the timer. There is also a control \u0026lt;\u0026lt;inicialización>>, which caused the return timer to original time, a control \u0026lt;\u0026lt;repetición>>, which allows the timer to repeat this as many times as this control is activated, and control \u0026lt;\u0026lt;cancelación>>, To cancel the alarm.

processor dolby noise recuccion

this chip has been designed specifically to carry out noise reduction according to standard Dolby-B to single-channel audio. plus an internal power regulator. contains a set of amplifiers and needs some external RC networks. one of these networks, which includes five capacitors and three resistors, connected to four external terminals, while the second, which is the pathway feedback is formed by three resistors and three convictions working with internal rectifier circuit. These RC networks are carefully specified by the manufacturer to ensure the collection of noise reduction system dolby-b desired.

five function calculator

this integrated circuit has just the four basic functions of calculus, as well as the charge and discharge rates. works with a simple keyboard consisting of keys c-ce, the ten numeric keys and six function keys but the decimal point. is the typical pocket calculators economic and contains all the logic and memory functions in a single integrated 28 terminals. in many advanced calculators used by many other more complex integrated circuits that provide more than eight-digit display, but the five basic functions and some limited amount of memory, but its basic features are the same.

as shown in the figure below, the nine digits connections are shared between the keyboard and display. three lines from the keyboard indicate the integrated column of keys has been pressed. combining this information with that digit. when you press a key on the keyboard, the same set of nine lines validates one of the eight-digit display, lighting l corresponding seven-segment digit. the other entries are the external oscillator and the oscillator signal validation.

Luis Fernando Cantor Well

19135529

Electronic Engineering, Solid state electronics

Section 2

Long, Flawy And Colourfull Skirts

Ciruit Integrated Integrated Integrated

power amplifier (follower linear)

power amplifiers are basically amplifiers that class usually have a voltage gain of 1 and work effectively as in transformers impedances *. its main characteristic is its ability to handle significant outflows. followers are sometimes called linear circuits similar to transistor emitter follower. Power amplifiers are often used in conjunction with operational amplifiers within the feedback loop to provide a current additional output.

differential amplifier

differential amplifiers have two input terminals, isolated both in respect of mass through the same impedance as shown in Figure 2 . basically similar to the class voltage amplifiers, differential amplifier only amplifies the voltage difference between its two input terminals. signals appearing in both terminals are amplified, allowing the differential amplifier to extract small signals in the presence of strong electromagnetic interference. this ability to reject signals common to both input terminals are specified in terms of common mode rejection. representative component is the sprague ULN-2047.

Figure 2 .- Amplifier Differential

isolation amplifier

consisting of several stages of amplification, the amplifier input is either electrically While optically isolated output (Fig. 3). the input amplifier is usually of differential modulated radio frequency in its output, which is carried through an rf transformer to the second stage, which is demodulated and filtered. power supply for the input amplifier section also must be isolated so that there is no connection at low frequencies or continuous between-inlet and outlet sections of the amplifier. the performance of optical isolation amplifiers is similar, and replaced by an rf transformer opto-coupler. isolation amplifiers are usually encapsulated in a unit and are used in applications requiring very low levels of behavior continues or through food. isolation amplifiers always require isolated power supplies and adequately insulated cables between power supply and amplifier. in some cases batteries are used to circumvent the problem of isolation of the power supply. representative component is the analog devices ad293.

consumer ICs

encompassed integrated circuits in this category are those offered by manufacturers for use in equipment classified as \u0026lt;\u0026lt;electrónica of consumo>>. Obviously, the CI used in watches, smoke detectors, televisions and calculators fall into this category. integrated circuits used in electrical timers are the same as those used in industrial clocks, and the microprocessor used to control a microwave or an electronic game will also be encompassed as consumer ci. this classification problem is marked by the fact that for any given function, such as the CI of a clock, a calculator or a CI for an electronic game, there are many different models, some selling only the manufacturer of the product available for consumption and other electronics distributors. some of these ci are so exclusive that even never have been published specifications, and some have been developed exclusively for a calculator, clock or game. integrated circuits designed for automatic cameras, for example, seem to belong mostly to this category.

only a few manufacturers publish data and custom integrated circuits for only a few types. the vast majority of integrated circuits used in mass market Custom designs are apparently consumption and need for spare parts only original equipment manufacturer has them in stock.

the ci of consumption are almost always large-scale circuit integration and often contain both analog and digital circuits. in this section were related to consumption of integrated circuits according to consumer equipment that are used. each is a representative example those of an acetate standard and custom designs that perform a particular function. where its function is combined with others, may be differences in their characteristics other minor differences, but the core functionality described here is specific to each type of integrated circuit.

alarm circuit

this circuit provides all necessary functions for burglar alarms, temperature, humidity and other types of security systems. including positive and negative entries with a noise suppression signal as shown in Figure 4. one of the features of this CI is its ability to detect the discharge of the battery. output current can be adjusted to the excitement of speakers speakers or other audio or visual indicator. has separate inputs for connecting and disconnecting switches for alarm. These switches usually work powered battery consumption requirements of this type of integrated circuit should be minimized.

Luis Fernando Cantor Well

19135529

Electronic Engineering, Solid State Electronics

Section 2

Does Purell Kill Viruses

Analog Integrated Circuits

The analog integrated circuits are fabricated used a variety of semiconductor technologies such as bipolar, field effect, metal oxides and combinations of these three. In most cases the user is not interested in this aspect of Integrated Circuits, as it can only base its work on the manufacturer's specifications. The technology used in the manufacture of integrated circuits is important for the user, because these are used in "logic families, with shared electrical specifications to ensure compatibility. Circuits Analog integrated normally are selected according to individual criteria, and only is it important to support the power requirements. Even here, the majority of analog integrated circuits are available with wide margins of power, so that their use is often not determined by their compatibility.

going to describe different kinds of analog integrated circuits:

Amplifier Class A (linear)

In this amplifier, the input signal is reproduced , increased in amplitude with exactly the same waveform at the output. To this end, the quiescent point (Q) is at the center of the curve of collector current (Ic) so that both the input signal and amplified output signal work only in the linear area of \u200b\u200bthe same. Ic is always projection (Fig. 1) Class A amplifiers are used whenever the output waveform is to be the same, with minimal distortion, the input signal. Operational amplifiers and amplifiers "small signal" such as radio frequency amplifiers, intermediate frequency amplifiers, preamps, etc., Are basically amplifiers in Class A.

Figure 1 .- Amplifier Class

Class AB Amplifier

In this type of amplifier operating point (Q) is below the midpoint of the linear portion of the curve Ic. As a result it has to be one half of the output is a linear playback of a half inning, but the second half of the output is partially suppressed. There are two versions Class Class AB1 and AB2. In Class AB2 point Q is close to the cutoff, in Class AB1 this is approximately 20% or 30% above the cutoff. Both versions used in push-pull circuit minimizing crossover distortion by, mutual compensation. The Class AB1 and AB2 amplifiers are widely used in exciting speakers and servo motors, applications that require linear amplification sinusoidal moderate powers.

Class B Amplifier

In this type of amplifier, the operating point (Q) is situated exactly at the cutting point of the curve of the integrated circuit, taking this as a result of amplification of one half cycle of sinusoidal input signal. Class B amplifiers are routinely used in complementary push-pull configuration. In this configuration, one of the amplifiers work on positive half cycles of the input signal, while the other does on the negative half-cycle sinusoidal input signal. Widely used as audio amplifiers, servo amplifiers and similar applications where high linearity is essential in the sinusoidal output signal, Class B amplifiers have an excellent efficiency and good behavior with regard to the presence of harmonics of second and third order. Displays some distortion in the crossover point due to the slight nonlinearity of the curve Ic at this point. The component representation of these amplifiers is ek Fairchild TBA 810S.

Class C Amplifier

In Class C amplifiers, the operating point (Q) is twice the cutoff point of the curve Ic. Only one half of a half cycle sinusoidal signal is amplified to the output. Class C amplifiers are usually used in radio frequency oscillators and, in some Where radio frequency transmitters. In these applications the effect of the resonant circuit provides the other half of the cycle. High efficiency is an essential characteristic for class C amplifiers in radio frequency circuits designed and adjusted properly.

Luis Fernando Cantor Well

19135529

Electronic Engineering, Solid state electronics

Section 2

Salix Alba Caerulea Usa

Types of Integrated Circuits Ciruit

Manufacture Integrated Circuits

available digital integrated circuits manufactured from silicon wafers. processing of silicon chips for IC or is relatively complicated.

The silicon used for the manufacture of chips is a purity of 99.9999999% of the order. Once synthesized, the silicon is melted in an inert atmosphere and crystallizes in the form of cylindrical bars of up to 10cm in diameter and 1 m long.

Each bar is cut into pellets 0.25 to 0.50 mm thick and the surfaces of the latter are polished to be shiny. depending on their size, you get hundreds of identical circuits (chips) on both surfaces by a process called planar, the same transistors used to mass produce ..

To manufacture a chip, the silicon wafers are processed first to make transistors. a silicon wafer itself is an insulator and does not conduct current. transistors are created by adding impurities such as phosphorus or arsenic in certain areas of the pill. connections are made through metal lines.

Every feature on the tablet form in the regions selected by spraying a protective chemical called light-sensitive photoresist, which forms a thin film on the surface of the tablet. the tablet is then bombarded with light, using a precise slide projector called boresight.

The aligner has a very small device called a mask, which prevents light falls on specific points of the tablet, when the light reaches a certain area of \u200b\u200bthe tablet eliminates the photoresist present in that area. this process is called photolithography.

Through a process of development, the chemical is deposited in regions exposed by the light and ignore concealed by the mask. these last areas still remain covered with "photoresist".

boresight accuracy determines how fine can be a Rasta. In the early 70's, it was difficult to make transistors smaller than 10 microns in size. Now the lower transistor sizes reach a speed of response of the device.

Then the pad is heated to high temperatures, this causes the unprocessed silicon surface becomes silicon oxide (SiO2). The SiO2 is spread over the surface of the wafer and form thereon a thin insulating film of a few microns thick.

This will get the first level of metallization of chips. To get a new metallization layer, the SiO2 is back with "photoresist" and exposed to boresight, repeating the same procedure used with silicon of the first level.

The different layers grow over each other forming a sandwich-like structure, with SiO2 as the bread and the metal or doped silicon as the sausage, most Integrated Circuits are not made with more than three layers of metallization.

materials integrated circuits

integrated circuits are made of silicon that serves as a base where they make transistors, diodes and resistors. Integrated circuits containing hundreds of these components distributed in an orderly way, this is achieved through a technique called photolithography which allows you to sort thousands of components on a small plate of silicon.

Classification according to Integrated Circuits structure

The classification of integrated circuits according to its structure can be based on the number of gates used to implement the specific function of the chip (called scale integration) as we know, the gates are basic building blocks of all digital circuits.

Integration scales are 4: SSI, MSI, LSI, VLSI, and then we will see each of them.

SSI Small Scale Integration .- Means (small scale integration) and includes the chips that contain less than 13 gates. Examples: gates and flip flops. SSI integrated circuits are manufactured using technologies TTL, CMOS and ECL. the first integrated circuits were SSI.

MSI Medium Scale Integration .- Mean (medium scale integration), and includes the chips that contain from 13 to 100 gates. Examples: encoders, registers, counters, multiplexers, encoders and multiplexers. MSI integrated circuits are manufactured using technologies TTL, CMOS and ECL.

.- LSI Large-Scale Integration means (high-scale integration) and includes chips containing 100 to 1000 gates. Examples: memory, arithmetic and logic units (ALU's), microprocessors of 8 and 16 bits. LSI Integrated Circuits are mainly manufactured using technologies I2L, nMOS and pMOS.

means VLSI .- Very Large Scale Integration (very high scale integration) and includes chips containing more than 1000 gates examples: micro-processor 32-bit micro-controllers, systems data acquisition. Integrated Circuits VSLI technologies are also made using TTL, CMOS and PMOS.

Luis Fernando Cantor Well

19135529

Ingenieria Electronica, Electronica De Estados sólidos

Seccion 2

Electric Wheelchair Joystick Hack

Integrierte Optik

integrated passive optical component

Passive optical components are integrated planar optical waveguide structures (PLWL, Eng. PLC), in which several features passive waveguide are monolithically integrated on a chip. Such components are now in large Volumes for fiber optic transmission systems (FTTH) is used. The function of these components is mainly the distribution of the light signals from a transmission fiber on many fibers or their reversal. Such branching agents, also called chips that allow a tree as they are in the PON systems needed (eg G-PON). Today, monomode splitters 1 and 2 × N × N with up to 64 channels and are commercially available in the entire frequency range of standard telecom fiber from 1260 to 1650 nm can be used.

which has long been known and field-proven technology for manufacturing such components is based on the ion exchange process in glass (Ken Koizumi, 1971). Here are generated by an appropriate photolithographic mask metal sodium ions of the glass localized by silver ions replaced. The silver ions cause an increase in the refractive index given by the mask paths and shape thus the waveguide structure.

result from this first purely thermal ion exchange sufficient surface waveguide, the geometry and transmission characteristics have not the technological requirements for loss and environmental stability. This is achieved by a second electric field guided by diffusion, in which one of the near-surface Silver ions with sodium ions from a salt melt in the glass buried inside. The resulting fibers are about 15 micrometers below the glass surface and show excellent transmission characteristics and long-term stability. ^[1] The OPAL network of Deutsche Telekom are produced in this way waveguide in use since 1993 and they show no signs of degeneration. ^[2] . In Germany, such waveguide components from the company IOT (former subsidiary of Schott Glass and Carl Zeiss) under a by the German Federal Government developed funded national research and development project in the 1980s and today by the company LEONI Fiber Optics GmbH produced.

An alternative chip technology is based on deposition of fused silica or doped silica glass films on a substrate of silicon or quartz. Here, the waveguide structures formed by etched out from a higher refractive index layer (eg, a germanium-doped silica glass layer). The resulting structures are then covered by another layer of quartz glass. Is called in this way produced passive structures as "Silica on Silicon," or "Silica on silica waveguide (SIOS). As the ion-exchanged waveguides SIOS-optic cables are also low loss and broadband. However, they state because of the layered structure of materials of different thermal expansion of a much higher polarization sensitivity especially with fluctuating temperatures.

By modifying the production parameters can be developed, other fiber properties. Passive integrated optical waveguide chips are for wavelengths down to 600 nm. More complex structures such as interferometers or wavelength-dependent functions can be realized. Such complex optical Chips are available for different applications such as sensors, instrumentation, diagnostics, etc., of interest because they give the possibility of a strong miniaturization and significant cost savings through integration.

Luis Fernando Cantor Bueno

19135529

Ingenieria Electronica, Electronica De Estados sólidos

Seccion 2

Cost Of The Wood Gun Boiler

Integrierte Optik

The Integrated optics (IO)

is that part of the optics that deals with the development of integrated optical systems . These systems are housed on a substrate and are characterized by a high functionality ( light sources , waveguide , beam splitter , intensity or phase modulators , filters, switches, etc.). Integrated optics is integrated circuits (IC) are comparable, but the integration density not as high as in the ICs.

Since the integrated optics is very interesting for communication systems and sensors, currently taking place here a lot of research and development to create new modules. It seeks to build all of an optical communication network necessary functions on an integrated optical circuit to accommodate in order to avoid having to use electrical signals.

materials

Typical materials Integrated optics are glass, silicon , polymers (especially photopolymers ) and dielectric crystals, for example lithium . The latter interesting electro-optical , acoustooptic and nonlinear optical has properties. To produce this material optical circuits with specific functions, the crystal with Titan doped , edited with proton exchange process , or doped with elements from the group of rare earth . Amp

Micro-optical laser, and produce doping element

order laser active elements or optical amplifier, glasses or crystals with the elements from the group of rare earths (praseodymium , neodymium , erbium, thulium , ytterbium) doped.
is most interesting erbium, as they may generate erbium-doped crystals, glasses and optical fibers infrared in the range of 1550 nm or strengthen a wavelength in the of silica glass ( quartz ) consisting of glass fibers attenuated very little is. This wavelength range is therefore primarily used in fiber optic networks the telecommunications .

be pumped Erbium-doped Lithiumniobatlaser and erbium-doped fiber amplifier with diode lasers with a wavelength of 980 nm or 1480nm. The chart at right shows the energy levels.

come as the radiation source in many cases semiconductor laser directly used. You can also operate at 1550 nm.

mixer and optical parametric oscillators

mixers, frequency multipliers and optical parametric oscillators ( OPO ) are used for frequency conversion to get out coherent light a frequency to generate coherent light at other frequencies. There are frequencies associated with the current laser sources can not be covered. through a nonlinear element can laser light in another frequency range, converted or Laser durchstimmbarer auch ein geschaffen werden.

Luis Fernando Cantor Well

19135529

Electronic Engineering, Solid State Electronics Section 2

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SPECIAL INTEGRATED CIRCUITS

today for any type of circuit we need, it is likely that we can find a model of an integrated circuit that performs the same function or part of it. Thus, we have seen that we can find oscillators, multivibrators and voltage regulators, such as 723, as part of integrated electronics.

linear voltage controlled oscillator built with a ICL8038

Different models of integrated circuits are numerous and, therefore, it is somewhat difficult to know exactly which of the that there will fit best to our design. There are many catalogs from different manufacturers, in which applications are often specified for each chip. But one of the most important factors, which rarely is reflected in these catalogs, is the type and amount of external devices that we need to perform the function we want with the integrated circuit. Despite all this, with a little experience in handling these catalogs will be able to get find the integrated circuit is going to be more useful, either to the specific application we need or to provide, by some of the functions want.

As we know, the number of different types of integrated circuits is immense and very difficult to know everyone. We will try to learn a little more depth some of them. With so many types of integrated circuits classifications can be made from them are also numerous. One of these classifications ci divides into three types: linear analog or digital and high consumption ci (radio, TV, etc.).. Linear integrated circuits are those that allow for input signal range within which valid may take infinite values, as happens in the output. Digital integrated circuits, as discussed below, support only a finite set of input values, being typically "two" elements of the set. Linear circuits must meet many conditions, it is sometimes necessary to design one of these circuits knowing in advance the role that will play, although this type of construction is very expensive and, as we saw, to make a lot of the price series circuits becomes cheaper much. For this reason, usually manufactured from highly versatile integrated circuits that a single IC can be used to make different types of functions.

The VCO

An integrated circuit is widely used VCO. This is a precision function generator. VCO stands, in English, of the integrated circuit, mean: oscilator controlled voltage. An integrated circuit ICL8038 is a function generator with which we can generate signals with high accuracy and forms can be sine, square, triangular, sawtooth and pulse. For all this you only need the integrated circuit named above and very few external components. A very important application of the VCO is its use in synthesizers. The VCO is the core of a synthesizer. The stability of the entire instrument will depend on the performance of the VCO. Among the main characteristics of a VCO is able to select the frequency externally in which we work, being able to obtain a wide range of useful frequencies between 0.001 Hz and 300 Hz This selection can be performed using resistors and capacitors.

ICL8038 connected for minimal distortion

We can also modulate the frequency and the sweep with an external stress. The VCO has a wide temperature range for which stable output is achieved. If we connect with a PLL can still further reduce drift in temperature. Another important feature is that we can obtain a VCO output signals simultaneously on the sine, triangular and cosine. If the output is sinusoidal distortion is low and the voltage normally obtained at the output is high. Besides all these qualities, its handling is quite easy and we can get it to work perfectly with a few external components.

The XR2206

The XR2206 is also an integrated function generator. With it we can get a signal output sine, square, triangular, sawtooth type or a pulse train. It is quite stable against temperature variations and has great accuracy. In these circuits, as in the VCO, we have a wide range of valid frequencies, ranging from 0.01 Hz to over 1 MHz and can be adjusted externally. You may also modulate the output signal amplitude and frequency using an external voltage. This integrated circuit is widely used for communications and instrumentation, and, when needed sinusoidal tone modulated FM or AM, is also used. We can shift the oscillation frequency using external control voltage. By doing this we will introduce a small distortion factor but it will be so small that we are worth this small disadvantage compared to the benefits it produces. These integrated circuits are made up of four parts: a VCO (voltage controlled oscillator), an analog multiplier and wave configurator, a gain amplifier and a set of circuit breakers. The main features of the ci are the low signal distortion and excellent stability. As we have seen, they also have a large displacement frequency, low sensitivity to variations in supply and high supply voltage range. Generators are often used as sine waves, square, triangular, etc. AM and FM generators, tone generators, frequency converters, voltage, etc..

Voltage Comparator

We know that with an operational amplifier coupled with some external device, mostly resistance, we could build a voltage comparator. We also have a series of integrated circuits, LM710, voltage comparators that are high speed. They are designed to be used in precision digital sensors and to replace operational amplifiers which function to compare stress when we need a high speed response. This family has an input difference and is well beyond levels that are compatible with the vast majority of logic families. It is a fairly integrated circuit stable against temperature changes. It consists of a silicon chip doped with gold and this type of doping which makes these circuits are much faster than operational amplifiers. In addition, you can not compare the great advantages that integrated circuits due to their minimum size and capacity of the wiring with discreet circuits that perform the same function. Among the applications of the LM710 include the following: can be used as pulse width modulators, voltage comparators, A / D and high-speed sensors operating in automated measuring equipment. There are also some applications for these integrated circuits within digital systems. Because of its low cost are often quite used.

The PLL

PLL's name comes from the initials of its name in English Phase Locked Loop. Speaking of a PLL we are referring to a feedback circuit. When discussing the PLL loop we think that it behaves like any servo system or closed loop feedback. The loop consists of a filter, a phase detector and a VCO. In a PLL we also find two dividers, which are often very necessary. For example, we use the PLL in a data communication system for a stable clock and free of fluctuations from a fluctuating input. If we have a variation whose amplitude is very large, it will be necessary to divide the input clock to reduce the amplitude of this variation and it is less than a time interval.

diagram of a PLL

Another example might be to use the PLL as frequency synthesizer. But the dividers can bring some problems, because if you introduce a big dividing factor in the feedback loop can greatly reduce the loop gain, and this will lead to a decline in the response to any changes that occur in input. Therefore, the great dividers should be avoided in feedback loop. Many of these circuits do not have a linear behavior because the phase detector output is not proportional to the phase error and the VCO output frequency does not keep a linear relationship with voltage control. But, in most cases, the PLL behave as a linear circuit and thus we will see.

One of the components used in the feedback loops are phase detectors. Phase detectors, as its name suggests, are able to determine the gap between two signals. There are a variety of them, of which we highlight the following: sampling phase detectors and retention type phase detector discriminator, phase detector multiplier type digital phase detectors. Depending on the application for which we will use the PLL will have to put a phase detector or another, since there is no one that's better, it depends on what we give to the circuit. To choose a detector or the other must take into account two main factors: the type of input signal and the error range of input phase in which the output is linear. Depending on the type of input signal that we will implement the PLL will be using a type of phase detector or another since, for example, a cosine input and digital input sensors require different phase. On the other hand, as the interval phase error of the entry in which the output is linear we will also use a phase detector or another. The broader the range most useful will be the phase detector to control the loop and also the noise will affect fewer. Phase detectors and digital multiplier type are the most commonly used. The former are useful when the input signal is cosine and the second type, as its name suggests, are used for input signals of the digital type.

Voltage Controlled Oscillator

Within the feedback loop of a PLL than a filter and a phase detector is a VCO. As we know, the VCO is voltage-controlled oscillators. There are several types of VCO that can be used in the PLL, crystal oscillators, multivibrators LC and RC oscillators. As with the detection phase we use a VCO or the other depending on the type of application that we will give the PLL. The two factors we have analyzed to choose the most suitable type of VCO is the phase stability and range of control. The frequency of the VCO is subject to the input signal, but phase relationship oscillator output to the input will depend on the natural frequency of the oscillator. Therefore, it will greatly influence the type of VCO say. The natural frequency of oscillation will vary with temperature, time and input noise, producing a change in the output stage if very large may be lost grip. Therefore, for good stability, the frequency of the VCO must be as variable as possible against the temperature, time and noise. On the other hand, it is desirable for the VCO is related in a frequency range as large as possible, because the larger the range of control is easier to maintain the control loop.

PLL with a phase detector and frequency detector

These two factors can not be achieved at once, ie we must have a commitment to see that we need more in each application because if the control range is very large, the phase stability against noise and temperature changes will be pretty bad, and, conversely, if we have a very good stability control interval will be small. Crystal oscillators are more stable but its control range is quite small. Are used in frequency synthesizers and clock synchronizers. However RC multivibrators in a range much greater control but its stability against the possible changes is not so good. They are used as FM demodulators and decoders tone.

As noted above, the input noise of a PLL is a factor that along with temperature and aging of the devices, can destabilize the circuit. Speaking of noise we are referring to unwanted signals that are mixed with the input signal and may even get we do not know what type of input signal or the duration. A very important feature in the PLL is the bandwidth of the noise. According to the application for which we will use the PLL we have to decide the bandwidth of noise.

modulation Follower designed with a PLL

Normally we have two kinds of PLL, a carrier tracking and other monitoring of modulation. With the first we recover, for example, the clock input signal. This clock must have a frequency modulation or phase or a considerable amount of noise and because of this must have a pass band as narrow as possible. The other types are tracking PLL Modulation working as discriminators, the output of the filter should reproduce the spectrum of the baseband and the frequency modulation or phase. In the latter case, the bandwidth of the loop should be wider than the highest modulating frequency. An important factor in treatment of noise is the noise threshold in the PLL. We have assumed that, despite having input noise, the loop is "subject" and this is not true at all. If the noise exceeds a certain value, called threshold of noise, the loop will start losing cycles and may lose the "subject" and will no more linear. The noise threshold of a PLL depends on the structure of the loop, more precisely the phase detector and filter. Another factor that we must also take into account the proper functioning of the loop in the presence of input noise is the frequency spectrum. If we stay within a appropriate frequency range, the loop noise quite well tolerated, but if we get out of that range will have many more problems.

An example of an integrated circuit is the LM565 PLL. The feedback loop of the PLL comprises a VCO, an operational amplifier having a resistor connected to the output and a phase detector, which is of type multiplier, as in most monolithic integrated circuit PLL. By using this type of phase detector we must ensure that the substantial changes in input frequency will not cause large changes in the output of the detector. This PLL can have several applications, among which is its use as a follower of modulation.

internal block diagram of a LM565

The PLL are widely used in electronic analog and digital. Applications include most common are frequency synthesizers, phase and frequency demodulators, coherent amplitude modulators, tone decoders, bit synchronizers, etc.. The PLL is used as frequency synthesizers in communication systems that require carrier frequencies in discrete intervals for a fixed space between channels, for example, the UHF channel band. The PLL that we will use in these applications has a programmable counter in the feedback loop. Another application of the PLL are tone decoders that use the principle that if the bandwidth of a PLL loop is small you can only have an indication of restraint if the input frequency is very near the center of the natural frequency of the VCO. Therefore, to detect a tone center frequency of the VCO must be adjusted to the pitch, so we're going to need a PLL for each of the tones we want to detect. Another application is to obtain a demodulated signal based on a modulated.

CRF

Lenny Z. Perez M

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