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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

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