Category: linear Integrated Circuits Applications

Basics Of Integrated Circuits An electronic circuit is a group of electronic components connected for a specific purpose. A simple electronic circuit can be designed easily because it requires few discrete electronic components and connections. However, designing a complex electronic circuit is difficult, as it requires more number of discrete electronic components and their connections. It is also time taking to build such complex circuits and their reliability is also less. These difficulties can be overcome with Integrated Circuits. Integrated Circuit (IC) If multiple electronic components are interconnected on a single chip of semiconductor material, then that chip is called as an Integrated Circuit (IC). It consists of both active and passive components. This chapter discusses the advantages and types of ICs. Advantages of Integrated Circuits Integrated circuits offer many advantages. They are discussed below − Compact size − For a given functionality, you can obtain a circuit of smaller size using ICs, compared to that built using a discrete circuit. Lesser weight − A circuit built with ICs weighs lesser when compared to the weight of a discrete circuit that is used for implementing the same function of IC. using ICs, compared to that built using a discrete circuit. Low power consumption − ICs consume lower power than a traditional circuit,because of their smaller size and construction. Reduced cost − ICs are available at much reduced cost than discrete circuits because of their fabrication technologies and usage of lesser material than discrete circuits. Increased reliability − Since they employ lesser connections, ICs offer increased reliability compared to digital circuits. Improved operating speeds − ICs operate at improved speeds because of their switching speeds and lesser power consumption. Types of Integrated Circuits Integrated circuits are of two types − Analog Integrated Circuits and Digital Integrated Circuits. Analog Integrated Circuits Integrated circuits that operate over an entire range of continuous values of the signal amplitude are called as Analog Integrated Circuits. These are further classified into the two types as discussed here − Linear Integrated Circuits − An analog IC is said to be Linear, if there exists a linear relation between its voltage and current. IC 741, an 8-pin Dual In-line Package (DIP)op-amp, is an example of Linear IC. Radio Frequency Integrated Circuits − An analog IC is said to be Non-Linear, if there exists a non-linear relation between its voltage and current. A Non-Linear IC is also called as Radio Frequency IC. Digital Integrated Circuits If the integrated circuits operate only at a few pre-defined levels instead of operating for an entire range of continuous values of the signal amplitude, then those are called as Digital Integrated Circuits. In the coming chapters, we will discuss about various Linear Integrated Circuits and their applications. Basics Of Operational Amplifier Operational Amplifier, also called as an Op-Amp, is an integrated circuit, which can be used to perform various linear, non-linear, and mathematical operations. An op-amp is a direct coupled high gain amplifier. You can operate op-amp both with AC and DC signals. This chapter discusses the characteristics and types of op-amps. Construction of Operational Amplifier An op-amp consists of differential amplifier(s), a level translator and an output stage. A differential amplifier is present at the input stage of an op-amp and hence an op-amp consists of two input terminals. One of those terminals is called as the inverting terminal and the other one is called as the non-inverting terminal. The terminals are named based on the phase relationship between their respective inputs and outputs. Characteristics of Operational Amplifier The important characteristics or parameters of an operational amplifier are as follows − Open loop voltage gain Output offset voltage Common Mode Rejection Ratio Slew Rate This section discusses these characteristics in detail as given below − Open loop voltage gain The open loop voltage gain of an op-amp is its differential gain without any feedback path. Mathematically, the open loop voltage gain of an op-amp is represented as − $$A_{v}= frac{v_0}{v_1-v_2}$$ Output offset voltage The voltage present at the output of an op-amp when its differential input voltage is zero is called as output offset voltage. Common Mode Rejection Ratio Common Mode Rejection Ratio (CMRR) of an op-amp is defined as the ratio of the closed loop differential gain, $A_{d}$ and the common mode gain, $A_{c}$. Mathematically, CMRR can be represented as − $$CMRR=frac{A_{d}}{A_{c}}$$ Note that the common mode gain, $A_{c}$ of an op-amp is the ratio of the common mode output voltage and the common mode input voltage. Slew Rate Slew rate of an op-amp is defined as the maximum rate of change of the output voltage due to a step input voltage. Mathematically, slew rate (SR) can be represented as − $$SR=Maximum:of:frac{text{d}V_{0}}{text{d}t}$$ Where, $V_{0}$ is the output voltage. In general, slew rate is measured in either $V/mu:Sec$ or $V/m:Sec$. Types of Operational Amplifiers An op-amp is represented with a triangle symbol having two inputs and one output. Op-amps are of two types: Ideal Op-Amp and Practical Op-Amp. They are discussed in detail as given below − Ideal Op-Amp An ideal op-amp exists only in theory, and does not exist practically. The equivalent circuit of an ideal op-amp is shown in the figure given below − An ideal op-amp exhibits the following characteristics − Input impedance $Z_{i}=inftyOmega$ Output impedance $Z_{0}=0Omega$ Open loop voltage gaine $A_{v}=infty$ If (the differential) input voltage $V_{i}=0V$, then the output voltage will be $V_{0}=0V$ Bandwidth is infinity. It means, an ideal op-amp will amplify the signals of any frequency without any attenuation. Common Mode Rejection Ratio (CMRR) is infinity. Slew Rate (SR) is infinity. It means, the ideal op-amp will produce a change in the output instantly in response to an input step voltage. Practical Op-Amp Practically, op-amps are not ideal and deviate from their ideal characteristics because of some imperfections during manufacturing. The equivalent circuit of a practical op-amp is shown in the following figure − A practical op-amp exhibits the following characteristics − Input impedance, $Z_{i}$ in the order of Mega ohms. Output impedance, $Z_{0}$

Differentiator And Integrator The electronic circuits which perform the mathematical operations such as differentiation and integration are called as differentiator and integrator, respectively. This chapter discusses in detail about op-amp based differentiator and integrator. Please note that these also come under linear applications of op-amp. Differentiator A differentiator is an electronic circuit that produces an output equal to the first derivative of its input. This section discusses about the op-amp based differentiator in detail. An op-amp based differentiator produces an output, which is equal to the differential of input voltage that is applied to its inverting terminal. The circuit diagram of an op-amp based differentiator is shown in the following figure − In the above circuit, the non-inverting input terminal of the op-amp is connected to ground. That means zero volts is applied to its non-inverting input terminal. According to the virtual short concept, the voltage at the inverting input terminal of opamp will be equal to the voltage present at its non-inverting input terminal. So, the voltage at the inverting input terminal of op-amp will be zero volts. The nodal equation at the inverting input terminal”s node is − $$Cfrac{text{d}(0-V_{i})}{text{d}t}+frac{0-V_0}{R}=0$$ $$=>-Cfrac{text{d}V_{i}}{text{d}t}=frac{V_0}{R}$$ $$=>V_{0}=-RCfrac{text{d}V_{i}}{text{d}t}$$ If $RC=1sec$, then the output voltage $V_{0}$ will be − $$V_{0}=-frac{text{d}V_{i}}{text{d}t}$$ Thus, the op-amp based differentiator circuit shown above will produce an output, which is the differential of input voltage $V_{i}$, when the magnitudes of impedances of resistor and capacitor are reciprocal to each other. Note that the output voltage $V_{0}$ is having a negative sign, which indicates that there exists a 1800 phase difference between the input and the output. Integrator An integrator is an electronic circuit that produces an output that is the integration of the applied input. This section discusses about the op-amp based integrator. An op-amp based integrator produces an output, which is an integral of the input voltage applied to its inverting terminal. The circuit diagram of an op-amp based integrator is shown in the following figure − In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. That means zero volts is applied to its non-inverting input terminal. According to virtual short concept, the voltage at the inverting input terminal of op-amp will be equal to the voltage present at its non-inverting input terminal. So, the voltage at the inverting input terminal of op-amp will be zero volts. The nodal equation at the inverting input terminal is − $$frac{0-V_i}{R}+Cfrac{text{d}(0-V_{0})}{text{d}t}=0$$ $$=>frac{-V_i}{R}=Cfrac{text{d}V_{0}}{text{d}t}$$ $$=>frac{text{d}V_{0}}{text{d}t}=-frac{V_i}{RC}$$ $$=>{d}V_{0}=left(-frac{V_i}{RC}right){text{d}t}$$ Integrating both sides of the equation shown above, we get − $$int{d}V_{0}=intleft(-frac{V_i}{RC}right){text{d}t}$$ $$=>V_{0}=-frac{1}{RC}int V_{t}{text{d}t}$$ If $RC=1sec$, then the output voltage, $V_{0}$ will be − $$V_{0}=-int V_{i}{text{d}t}$$ So, the op-amp based integrator circuit discussed above will produce an output, which is the integral of input voltage $V_{i}$, when the magnitude of impedances of resistor and capacitor are reciprocal to each other. Note − The output voltage, $V_{0}$ is having a negative sign, which indicates that there exists 1800 phase difference between the input and the output. Learning working make money

Converters Of Electrical Quantities Voltage and current are the basic electrical quantities. They can be converted into one another depending on the requirement. Voltage to Current Converter and Current to Voltage Converter are the two circuits that help in such conversion. These are also linear applications of op-amps. This chapter discusses them in detail. Voltage to Current Converter A voltage to current converter or V to I converter, is an electronic circuit that takes current as the input and produces voltage as the output. This section discusses about the op-amp based voltage to current converter. An op-amp based voltage to current converter produces an output current when a voltage is applied to its non-inverting terminal. The circuit diagram of an op-amp based voltage to current converter is shown in the following figure. In the circuit shown above, an input voltage $V_{i}$ is applied at the non-inverting input terminal of the op-amp. According to the virtual short concept, the voltage at the inverting input terminal of an op-amp will be equal to the voltage at its non-inverting input terminal . So, the voltage at the inverting input terminal of the op-amp will be $V_{i}$. The nodal equation at the inverting input terminal”s node is − $$frac{V_i}{R_1}-I_{0}=0$$ $$=>I_{0}=frac{V_t}{R_1}$$ Thus, the output current $I_{0}$ of a voltage to current converter is the ratio of its input voltage $V_{i}$ and resistance $R_{1}$. We can re-write the above equation as − $$frac{I_0}{V_i}=frac{1}{R_1}$$ The above equation represents the ratio of the output current $I_{0}$ and the input voltage $V_{i}$ & it is equal to the reciprocal of resistance $R_{1}$ The ratio of the output current $I_{0}$ and the input voltage $V_{i}$ is called as Transconductance. We know that the ratio of the output and the input of a circuit is called as gain. So, the gain of an voltage to current converter is the Transconductance and it is equal to the reciprocal of resistance $R_{1}$. Current to Voltage Converter A current to voltage converter or I to V converter is an electronic circuit that takes current as the input and produces voltage as the output. This section discusses about the op-amp based current to voltage converter. An op-amp based current to voltage converter produces an output voltage when current is applied to its inverting terminal. The circuit diagram of an op-amp based current to voltage converter is shown in the following figure. In the circuit shown above, the non-inverting input terminal of the op-amp is connected to ground. That means zero volts is applied at its non-inverting input terminal. According to the virtual short concept, the voltage at the inverting input terminal of an op-amp will be equal to the voltage at its non-inverting input terminal. So, the voltage at the inverting input terminal of the op-amp will be zero volts. The nodal equation at the inverting terminal”s node is − $$-I_{i}+frac{0-V_0}{R_f}=0$$ $$-I_{i}=frac{V_0}{R_f}$$ $$V_{0}=-R_{t}I_{i}$$ Thus, the output voltage, $V_{0}$ of current to voltage converter is the (negative) product of the feedback resistance, $R_{f}$ and the input current, $I_{t}$. Observe that the output voltage, $V_{0}$ is having a negative sign, which indicates that there exists a 1800 phase difference between the input current and output voltage. We can re-write the above equation as − $$frac{V_0}{I_i}=-R_{f}$$ The above equation represents the ratio of the output voltage $V_{0}$ and the input current $I_{i}$, and it is equal to the negative of feedback resistance, $R_{f}$. The ratio of output voltage $V_{0}$ and input current $I_{i}$ is called as Transresistance. We know that the ratio of output and input of a circuit is called as gain. So, the gain of a current to voltage converter is its trans resistance and it is equal to the (negative) feedback resistance $R_{f}$ . Learning working make money

Linear Integrated Circuits Applications Job Search Linear Integrated Circuits are solid state analog devices that can operate over a continuous range of input signals. Theoretically, they are characterized by an infinite number of operating states. Linear Integrated Circuits are widely used in amplifier circuits. Audience This tutorial is designed for readers who are aspiring to learn the concepts of Linear Integrated Circuits and their applications. It covers Linear Integrated Circuits such as opamp, timer, phase locked loop and voltage regulator ICs. After completing this tutorial, you will be able to know the functionality of various Linear Integrated Circuits and how to utilize them for a specific application, by combining with few additional electronic components. Prerequisites As a learner of this tutorial, you are expected to have a basic understanding of Electronic Circuits. If you are not familiar with these, we suggest you to refer to tutorials on Electronic Circuits first. That knowledge will be useful for understanding the concepts discussed in this tutorial. Learning working make money

Sinusoidal Oscillators An oscillator is an electronic circuit that produces a periodic signal. If the oscillator produces sinusoidal oscillations, it is called as a sinusoidal oscillator. It converts the input energy from a DC source into an AC output energy of a periodic signal. This periodic signal will be having a specific frequency and amplitude. The block diagram of a sinusoidal oscillator is shown in the following figure − The above figure mainly consists of two blocks: an amplifier and a feedback network.The feedback network takes a part of the output of amplifier as an input to it and produces a voltage signal. This voltage signal is applied as an input to the amplifier. The block diagram of a sinusoidal oscillator shown above produces sinusoidal oscillations, when the following two conditions are satisfied − The loop gain $A_{v}beta$ of the above block diagram of sinusoidal oscillator must be greater than or equal to unity. Here, $A_{v}$ and $beta$ are the gain of amplifier and gain of the feedback network, respectively. The total phase shift around the loop of the above block diagram of a sinusoidal oscillator must be either 00 or 3600. The above two conditions together are called as Barkhausen criteria. Op-Amp Based Oscillators There are two types of op-amp based oscillators. RC phase shift oscillator Wien bridge oscillator This section discusses each of them in detail. RC Phase Shift Oscillator The op-amp based oscillator, which produces a sinusoidal voltage signal at the output with the help of an inverting amplifier and a feedback network is known as a RC phase shift oscillator. This feedback network consists of three cascaded RC sections. The circuit diagram of a RC phase shift oscillator is shown in the following figure − In the above circuit, the op-amp is operating in inverting mode. Hence, it provides a phase shift of 1800. The feedback network present in the above circuit also provides a phase shift of 1800, since each RC section provides a phase shift of 600. Therefore, the above circuit provides a total phase shift of 3600 at some frequency. The output frequency of a RC phase shift oscillator is − $$f=frac{1}{2Pi RCsqrt[]{6}}$$ The gain $A_{v}$ of an inverting amplifier should be greater than or equal to -29, $$i.e.,-frac{R_f}{R_1}geq-29$$ $$=>frac{R_f}{R_1}geq-29$$ $$=>R_{f}geq29R_{1}$$ So, we should consider the value of feedback resistor $R_{f}$, as minimum of 29 times the value of resistor $R_{1}$, in order to produce sustained oscillations at the output of a RC phase shift oscillator. Wien Bridge Oscillator The op-amp based oscillator, which produces a sinusoidal voltage signal at the output with the help of a non-inverting amplifier and a feedback network is known as Wien bridge oscillator. The circuit diagram of a Wien bridge oscillator is shown in the following figure − In the circuit shown above for Wein bridge oscillator, the op-amp is operating in non inverting mode. Hence, it provides a phase shift of 00. So, the feedback network present in the above circuit should not provide any phase shift. If the feedback network provides some phase shift, then we have to balance the bridge in such a way that there should not be any phase shift. So, the above circuit provides a total phase shift of 00 at some frequency. The output frequency of Wien bridge oscillator is $$f=frac{1}{2Pi RC}$$ The gain $A_{v}$ of the non-inverting amplifier should be greater than or equal to 3 $$i.e.,1+frac{R_f}{R_1}geq3$$ $$=>frac{R_f}{R_1}geq2$$ $$=>R_{f}geq2R_{1}$$ So, we should consider the value of feedback resistor $R_{f}$ at least twice the value of resistor, $R_{1}$ in order to produce sustained oscillations at the output of Wien bridge oscillator. Learning working make money

Comparators A comparator is an electronic circuit, which compares the two inputs that are applied to it and produces an output. The output value of the comparator indicates which of the inputs is greater or lesser. Please note that comparator falls under non-linear applications of ICs. An op-amp consists of two input terminals and hence an op-amp based comparator compares the two inputs that are applied to it and produces the result of comparison as the output. This chapter discusses about op-amp based comparators. Types of Comparators Comparators are of two types : Inverting and Non-inverting. This section discusses about these two types in detail. Inverting Comparator An inverting comparator is an op-amp based comparator for which a reference voltage is applied to its non-inverting terminal and the input voltage is applied to its inverting terminal. This comparator is called as inverting comparator because the input voltage, which has to be compared is applied to the inverting terminal of op-amp. The circuit diagram of an inverting comparator is shown in the following figure. The operation of an inverting comparator is very simple. It produces one of the two values, $+V_{sat}$ and $-V_{sat}$ at the output based on the values of its input voltage $V_{i}$ and the reference voltage $V_{ref}$. The output value of an inverting comparator will be $-V_{sat}$, for which the input $V_{i}$ voltage is greater than the reference voltage $V_{ref}$. The output value of an inverting comparator will be $+V_{sat}$, for which the input $V_{i}$ is less than the reference voltage $V_{ref}$. Example Let us draw the output wave form of an inverting comparator, when a sinusoidal input signal and a reference voltage of zero volts are applied to its inverting and non-inverting terminals respectively. The operation of the inverting comparator shown above is discussed below − During the positive half cycle of the sinusoidal input signal, the voltage present at the inverting terminal of op-amp is greater than zero volts. Hence, the output value of the inverting comparator will be equal to $-V_{sat}$ during positive half cycle of the sinusoidal input signal. Similarly, during the negative half cycle of the sinusoidal input signal, the voltage present at the inverting terminal of the op-amp is less than zero volts. Hence, the output value of the inverting comparator will be equal to $+V_{sat}$ during negative half cycle of the sinusoidal input signal. The following figure shows the input and output waveforms of an inverting comparator, when the reference voltage is zero volts. In the figure shown above, we can observe that the output transitions either from $-V_{sat}$ to $+V_{sat}$ or from $+V_{sat}$ to $-V_{sat}$ whenever the sinusoidal input signal is crossing zero volts. In other words, output changes its value when the input is crossing zero volts. Hence, the above circuit is also called as inverting zero crossing detector. Non-Inverting Comparator A non-inverting comparator is an op-amp based comparator for which a reference voltage is applied to its inverting terminal and the input voltage is applied to its non-inverting terminal. This op-amp based comparator is called as non-inverting comparator because the input voltage, which has to be compared is applied to the non-inverting terminal of the op-amp. The circuit diagram of a non-inverting comparator is shown in the following figure The operation of a non-inverting comparator is very simple. It produces one of the two values, $+V_{sat}$ and $-V_{sat}$ at the output based on the values of input voltage $V_{t}$ and the reference voltage $+V_{ref}$. The output value of a non-inverting comparator will be $+V_{sat}$, for which the input voltage $V_{i}$ is greater than the reference voltage $+V_{ref}$. The output value of a non-inverting comparator will bee $-V_{sat}$, for which the input voltage $V_{i}$ is less than the reference voltage $+V_{ref}$. Example Let us draw the output wave form of a non-inverting comparator, when a sinusoidal input signal and reference voltage of zero volts are applied to the non-inverting and inverting terminals of the op-amp respectively. The operation of a non-inverting comparator is explained below − During the positive half cycle of the sinusoidal input signal, the voltage present at the non-inverting terminal of op-amp is greater than zero volts. Hence, the output value of a non-inverting comparator will be equal to $+V_{sat}$ during the positive half cycle of the sinusoidal input signal. Similarly, during the negative half cycle of the sinusoidal input signal, the voltage present at the non-inverting terminal of op-amp is less than zero volts. Hence, the output value of non-inverting comparator will be equal to $-V_{sat}$ during the negative half cycle of the sinusoidal input signal. The following figure shows the input and output waveforms of a non-inverting comparator, when the reference voltage is zero volts. From the figure shown above, we can observe that the output transitions either from $+V_{sat}$ to $-V_{sat}$ or from $-V_{sat}$ to $+V_{sat}$ whenever the sinusoidal input signal crosses zero volts. That means, the output changes its value when the input is crossing zero volts. Hence, the above circuit is also called as non-inverting zero crossing detector. Learning working make money