Biyani's Think Tank Concept based notes
Applied Electronics (B.Tech)
Shikha kamboo Asst. Professor Deptt. of Engineering Biyani International Institute of Engineering and Technology
]
Published by :
Think Tanks Biyani Group of Colleges
Concept & Copyright :
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While every effort is taken to avoid errors or omissions in this Publication, any mistake or omission that may have crept in is not intentional. It may be taken note of that neither the publisher nor the author will be responsible for any damage or loss of any kind arising to anyone in any manner on account of such errors and omissions. Leaser Type Setted by : Biyani College Printing Department
Preface
I
am glad to present this book, especially designed to serve the needs of the students.
The book has been written keeping in mind the general weakness in understanding the fundamental concepts of the topics. The book is self-explanatory and adopts the “Teach Yourself” style. It is based on question-answer pattern. The language of book is quite easy and understandable based on scientific approach. Any further improvement in the contents of the book by making corrections, omission and inclusion is keen to be achieved based on suggestions from the readers for which the author shall be obliged. I acknowledge special thanks to Mr. Rajeev Biyani, Chairman & Dr. Sanjay Biyani, Director (Acad.) Biyani Group of Colleges, who are the backbones and main concept provider and also have been constant source of motivation throughout this Endeavour. They played an active role in coordinating the various stages of this Endeavour and spearheaded the publishing work. I look forward to receiving valuable suggestions from professors of various educational institutions, other faculty members and students for improvement of the quality of the book. The reader may feel free to send in their comments and suggestions to the under mentioned address.
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Author
Syllabus UNIT-I Transistor: Transistor as an amplifier: low frequency, single stage and multistage amplifier. Regulated Power Supply: Capacitor filters for single-phase rectifiers. Application of 3-pinvoltage regulator Ics 78xx/79xx/317/337. UNIT –II OPAMP: Introduction to operational amplifiers. Applications of OPAMP: 1) Summing scaling, averaging, integrator and differentiator; 2) OPAMP as comparator 3) Instrumentation Amplifier and its applications. UNIT-III Digital Electronics: 1) Combinational circuits: multiplexers, demultiplexers, decoders, encoders. 2) Flip-flops': S-R F/F, clocked S-R F/F, D F/F, J-K F/F, T F/F 3) Counters: Asynchronous (ripple) counter, Asynchronous UP/DOWN counter, Synchronous counter,Synchronous UP/DOWN counter. 4) Registers: Serial-in, serial-out; Parallel-in, serial-out; Serial-in, parallel out; Serial/parallel in, Serial/parallel out. UNIT-IV D/A converters: R/ 2R register ladder. D/A converter. A/D converters: successive approx. A/D converter UNIT-V Microprocessor: Concept of microprocessor, software architecture of 8086, Addressing modes, Data transfer arithmetic logical, Jump/Call, String instructions, Writing simple assembly language programmers, Technical details of serial and parallel ports of IBM compatible PC.
Text/Reference Books 1. Millman, Halkias, “Basic Electronics”, Tata McGraw-Hill. 2. Coughlin and Driscoll, “Operational Amplifiers and Linear Integrated Circuits”, Prentice Hall of India. 3. Bray B.B., “8086 – 486 Intel Microprocessor,” Prentice Hall of India. 4. Hall, D., “8086 Microprocessor”, Tata McGraw-Hill
Unit-1
Transistor and Regulated Power Supply Q.1 Define Regulator power supply with diagram? Ans A regulated power supply is an embedded circuit; it converts unregulated AC into a constant DC. With the help of a rectifier it converts AC supply into DC. Its function is to supply a stable voltage (or less often current), to a circuit or device that must be operated within certain power supply limits. The output from the regulated power supply may be alternating or unidirectional, but is nearly always DC (Direct Current).
Q.2 What is rectifier? How to work of single phase half wave rectifiers with filter capacitor. Ans Rectifier circuits may be single-phase or multi-phase (three being the most common number of phases). Most low power rectifiers for domestic equipment are single-phase, but three-phase rectification is very important for industrial applications and for the transmission of energy as DC .
Single-phase Half-wave rectification In half wave rectification of a single-phase supply, either the positive or negative half of the AC wave is passed, while the other half is blocked. Because only one half of the input waveform reaches the output, mean voltage is lower. Half-wave rectification requires a single diode in a singlephase supply, or three in a three- phase supply. Rectifiers yield a unidirectional but pulsating direct current; half- wave rectifiers produce far more ripple than full-wave rectifiers, and much more filtering is needed to eliminate harmonics of the AC frequency from the output.
Q.2 Describe single phase full wave rectifier with diagram? Ans A full-wave rectifier converts the whole of the input waveform to one of constant polarity (positive or negative) at its output. Full-wave rectification converts both polarities of the input waveform to pulsating DC (direct current), and yields a higher average output voltage. Two diodes and a center tapped transformer, or four diodes in a bridge configuration and any AC source (including a transformer without center tap), Single semiconductor diodes, double diodes with common cathode or common anode, and four-diode bridges, are manufactured as single components.
Voltage regulators are found in almost every piece of electronic equipment, and range from very low voltage types (e.g. 3.3V used for many microprocessors) up to hundreds of volts as used in some valve amplifiers and other equipment that relies on high voltages. Not every voltage needs to be regulated. It is traditional to supply opamps used in audio with regulated supplies (typically ±15V), but this is primarily done to ensure low ripple (100 or 120Hz) and noise. Opamps don't care much if there's noise on the supply, and they are perfectly happy even if the supply voltages change a little while they are working. Provided their maximum operating voltage is not exceeded and the supplies remain high enough to allow the signal through without distortion, supply variations will not result in significant output variations. Q.4 What is voltage regulator? Show the block diagram of the IC voltage regulator Ans Voltage regulators are found in almost every piece of electronic equipment, and range from very low voltage types (e.g. 3.3V used for many microprocessors) up to hundreds of volts as used in some valve amplifiers and other equipment that relies on high voltages. Not every voltage needs to be regulated. It is traditional to supply opamps used in audio with regulated supplies (typically ±15V), but this is primarily done to ensure low ripple (100 or 120Hz) and noise. Opamps don't care much if there's noise on the supply, and they are perfectly happy even if the supply voltages change a little while they are working. Provided their maximum operating voltage is not exceeded and the supplies remain high enough to allow the signal through without distortion, supply variations will not result in significant output variations. However, this is generally considered unacceptable. The supplies to opamps should be regulated, because no opamp has an infinite PSRR, and it degrades at high frequencies as the open loop gain falls due to internal (or external) frequency compensation. In many cases, a simple
zener diode regulator may be sufficient, but these are inefficient and are considered very 'low tech' by modern standards.
Q.5 How to work 78xx IC in voltage regulator? Show the pin diagram of 7805 IC. Ans 78xx series ICs do not require additional components to provide a constant, regulated source of power, making them easy to use, as well as economical and efficient uses of space. Other voltage regulators may require additional components to set the output voltage level, or to assist in the regulation process. Some other designs (such as a switchedmode power supply) may need substantial engineering expertise to implement. 78xx series ICs have built-in protection against a circuit drawing too much current. They have protection against overheating and shortcircuits, making them quite robust in most applications. In some cases, the current-limiting features of the 78xx devices can provide protection not only for the 78xx itself, but also for other parts of the circuit.
7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable values can be connected at input and output pins depending upon the respective voltage levels. Pin Diagram: 7805 Voltage Regulator IC pin diagram, PinOut...
..
Unit-II
OPAMP Q.1 What is operation amplifier with inverting and non-inverting terminal. Show the symbolic diagram? Ans Operational amplifier (op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op-amp produces an output potential (relative to circuit ground) that is typically hundreds of thousands of times larger than the potential difference between its input terminals.
Operational amplifiers had their origins in analog computers, where they were used to do mathematical operations in many linear, non-linear and frequency- dependent circuits. The popularity of the op-amp as a building block in analog circuits is due to its versatility. Due to negative feedback, the characteristics of an op-amp circuit, its gain, input and output impedance, bandwidth etc. are determined by external components and have little dependence on temperature coefficients or manufacturing variations in the op-amp itself. Op-amps are among the most widely used electronic devices today, being used in a vast array of consumer, industrial, and scientific devices. Many standard IC op-amps cost only a few cents in moderate production volume; however some integrated or hybrid operational amplifiers with special performance specifications may cost over $100 US in small quantities. Op-amps may be packaged as components, or used as elements of more complex integrated circuits.
The op-amp is one type of differential amplifier. Other types of differential amplifier include the fully differential amplifier (similar to the opamp, but with two outputs), the instrumentation amplifier (usually built from three op-amps), the isolation amplifier (similar to the instrumentation amplifier, but with tolerance to common-mode voltages that would destroy an ordinary op-amp), and negative feedback amplifier (usually built from one or more op-amps and a resistive feedback network). Q.2
Explain characteristics of operation amplifier?
Ans
Op-amp characteristics-: 1 Ideal op-amps
An equivalent circuit of an operational amplifier that models some resistive nonideal parameters. An ideal op-amp is usually considered to have the following properties: Infinite open-loop gain G = vout / 'vin Infinite input impedance Rin, and so zero input current Zero input offset voltage Infinite voltage range available at the output Infinite bandwidth with zero phase shift and infinite slew rate Zero output impedance Rout Zero noise
Infinite Common-mode rejection ratio (CMRR) Infinite Power supply rejection ratio. These ideals can be summarized by the two "golden rules": I. voltage II.
The output attempts to do whatever is necessary to make the difference between the inputs zero. The inputs draw no current.
The first rule only applies in the usual case where the op-amp is used in a closed- loop design (negative feedback, where there is a signal path of some sort feeding back from the output to the inverting input). These rules are commonly used as a good first approximation for analyzing or designing op-amp circuits. None of these ideals can be perfectly realized. A real op-amp may be modeled with non-infinite or non-zero parameters using equivalent resistors and capacitors in the op-amp model. The designer can then include these effects into the overall performance of the final circuit. Some parameters may turn out to have negligible effect on the final design while others represent actual limitations of the final performance that must be evaluated. 2) Real op-amps Real op-amps differ from the ideal model in various aspects Real operational amplifiers suffer from several non-ideal effects: 3) Finite gain Open-loop gain is infinite in the ideal operational amplifier but finite in real operational amplifiers. Typical devices exhibit open-loop DC gain ranging from 100,000 to over 1 million. So long as the loop gain (i.e., the product of open-loop and feedback gains) is very large, the circuit gain will be determined entirely by the amount of negative feedback (i.e., it will be independent of open-loop gain). In cases where closed-loop gain must be very high, the feedback gain will be very low, and the low feedback gain causes low loop gain; in these cases, the operational amplifier will cease to behave ideally.
4) Finite input impedances The differential input impedance of the operational amplifier is defined as the impedance between its two inputs; the common-mode input impedance is the impedance from each input to ground. MOSFET-input operational amplifiers often have protection circuits that effectively short circuit any input differences greater than a small threshold, so the input impedance can appear to be very low in some tests. However, as long as these operational amplifiers are used in a typical high-gain negative feedback application, these protection circuits will be inactive. The input bias and leakage currents described below are a more important design parameter for typical operational amplifier applications. 5) Non-zero output impedance Low output impedance is important for low-impedance loads; for these loads, the voltage drop across the output impedance effectively reduces the open loop gain. In configurations with a voltage-sensing negative feedback, the output impedance of the amplifier is effectively lowered; thus, in linear applications, op- amp circuits usually exhibit a very low output impedance indeed. Low-impedance outputs typically require high quiescent (i.e., idle) current in the output stage and will dissipate more power, so low-power designs may purposely sacrifice low output impedance. 6) Input current Due to biasing requirements or leakage, a small amount of current (typically ~10 nanoamperes for bipolar op-amps, tens of picoamperes (pA) for JFET input stages, and only a few pA for MOSFET input stages) flows into the inputs. When large resistors or sources with high output impedances are used in the circuit, these small currents can produce large unmodeled voltage drops. If the input currents are matched, and the impedance looking out of both inputs are matched, then the voltages produced at each input will be equal. Because the operational amplifier operates on the difference between its inputs, these matched voltages will have no effect. It is more common for the input currents to be slightly mismatched. The difference is called input offset current, and even with matched resistances a small offset voltage (different from the input offset voltage below) can be produced. This offset voltage can create offsets or drifting in the operational amplifier.
7) Input offset voltage
This voltage, which is what is required across the op-amp's input terminals to drive the output voltage to zero, In the perfect amplifier, there would be no input offset voltage. However, it exists in actual opamps because of imperfections in the differential amplifier that constitutes the input stage of the vast majority of these devices. Input offset voltage creates two problems: First, due to the amplifier's high voltage gain, it virtually assures that the amplifier output will go into saturation if it is operated without negative feedback, even when the input terminals are wired together. Second, in a closed loop, negative feedback configuration, the input offset voltage is amplified along with the signal and this may pose a problem if high precision DC amplification is required or if the input signal is very small.[nb 2] 8) Common-mode gain A perfect operational amplifier amplifies only the voltage difference between its two inputs, completely rejecting all voltages that are common to both. However, the differential input stage of an operational amplifier is never perfect, leading to the amplification of these common voltages to some degree. The standard measure of this defect is called the common-mode rejection ratio (denoted CMRR). Minimization of common mode gain is usually important in noninverting amplifiers (described below) that operate at high amplification. 9) Power-supply rejection The output of a perfect operational amplifier will be completely independent from ripples that arrive on its power supply inputs. Every real operational amplifier has a specified power supply rejection ratio (PSRR) that reflects how well the op-amp can reject changes in its supply voltage. Copious use of bypass capacitors can improve the PSRR of many devices, including the operational amplifier. 10 Temperature effects All parameters change with temperature. Temperature drift of the input offset voltage Q.3
Write short note of summing scaling of operation amplifier?
Ans The Summing Amplifier is a very flexible circuit based upon the standard Inverting Operational Amplifier configuration. As its name suggests, the “summing amplifier” can be used for combining the voltage present on multiple inputs into a single output voltage.
We saw previously in the Inverting Operational Amplifier that the inverting amplifier has a single input voltage, ( Vin ) applied to the inverting input terminal. If we add more input resistors to the input, each equal in value to the original input resistor, Rin we end up with another operational amplifier circuit called a Summing Amplifier, “summing inverter” or even a “voltage adder” circuit as shown below. summing amplifier formula V
out=
RF (V 1+V 2+V 3 … .etc) R¿
However, if all the input impedances, ( Rin ) are equal in value, we can simplify the above equation to give an output voltage of: Summing Amplifier ckt
Q.4
Write short notes of Differentiator operation amplifier?
Ans The Op-amp Differentiator AmplifierThe basic Op-amp Differentiator circuit is the exact opposite to that of the Integrator Amplifier circuit that we looked at in the previous tutorial. Here, the position of the capacitor and resistor have been reversed and now the reactance, Xc is connected to the input terminal of the inverting amplifier while the resistor, Rƒ forms the negative feedback element across the operational amplifier as normal.
This Operational Amplifier circuit performs the mathematical operation of Differentiation, that is it “produces a voltage output which is directly proportional to the input voltage’s rate-of-change with respect to time“. In other words the faster or larger the change to the input voltage signal, the greater the input current, the greater will be the output voltage change in response, becoming more of a “spike” in shape. As with the integrator circuit, we have a resistor and capacitor forming an RC Network across the operational amplifier and the reactance ( Xc ) of the capacitor plays a major role in the performance of a Op-amp Differentiator.
Q.5
Write short note of integrating amplifier?
Ans The Op-amp Integrating Amplifier Operational amplifier can be used as part of a positive or negative feedback amplifier or as an adder or subtractor type circuit using just pure resistances in both the input and the feedback loop. But what if we were to change the purely resistive ( Rƒ ) feedback element of an inverting amplifier to that of a frequency dependant impedance, ( Z ) type complex element, such as a Capacitor, C. What would be the effect on the op-amps output voltage over its frequency range. By replacing this feedback resistance with a capacitor we now have an RC Network connected across the operational amplifiers feedback path producing another type of operational amplifier circuit commonly called an Op-amp Integrator circuit as shown below. Op-amp Integrator Circuit
Unit-3 Q.1 Describe the BCD to Decimal encoder? Ans The BCD-Decimal decoder converts each BCD code to its decimal equivalent.BCD to decimal decoders takes a 4 bit BCD as an input and produces 10 outputs to the decimal digits. The technique employed is also used in developing the 3-line-to-8-line decoder. The logic diagram of a BCD to decimal decoder using AND gates. When each output goes to HIGH when its corresponding BCD code is applied at its input.
Decimal to BCD encoder using OR gates
Q.2 Explain multiplexer and De-multiplexer with the help of truth table and logic diagrams? Ans Multiplexer-Multiplexer are also known as DATA SELECTORS. The term 'Multiplexer' means "many into one". MUX is a combinational logic circuit designed to switch one of several input lines through to a single common output by the use of a control signal. Multiplexer operate like very fast acting multiple position rotary switches connecting or controlling multiple input lines called "channels" one at a time to the output. Multiplexer is a method by which multiple analog signals or digitals data streams are combined into one signal over a shared medium. Schematic symbol for multiplexer is
The Block diagrams of multiplexer with n input lines, m select signals one output line. if the no. of n input lines is equal to 2m, the m select lines are required to select one of the n input lines.
DE-MULIPLEXER-De-multiplexer are also known as DATA DISTRIBUTORS. The term "de-multiplex" means one into many. A demultiplexer is a circuit that has one input and more than one output. it is used when a circuit to send a signal to one of many devices, its similar to decoder is used to select among many devices while a demultiplexer is used to send a signal among many devices. Schematic Symbols
The block diagram of de-multiplexer has one input lines, m select signals and n output signals. the select are used to determine to which output data input is connected
, As the de-multiplexer take one signal input data line and then switches it to any one of a no, of individual output lines one at a time. the de-multiplexer convert a serial data signal at the input to a parallel data at its output lines. its known as serial to parallel convertor. BLOCK DIAGRAMS-
Q.3 What is distinguish between Encoder and Decoder. Ans Encoder- An encoder performs the inverse operation of a decoder. hence, the process perform by encoder is called encoding. so, an encoder is a combinational logic circuit that converts an active input signal into a coded output signal. it has n input lines and m output lines, it encodes this active input to an coded binary with m bits.
The number of outputs is less than the number of inputs. The block diagrams of an encoder is as fellow:
DECODER-A decoder is a combinational circuit that changes a code into a set of signals. it is a called a decoder because it does the reverse of encoding. decoders are simple to design. A decoder is
similar to de-multiplexer but without any data input. A common decoder is line decoder which takes an n-digit binary no. and decodes it into 2nd output data lines, such that each output lines will be activated for only one of the possible combinational of inputs. In digital electronics, a decoder can take the form of a multiple-input, multiple-output logic circuit that converts coded input into coded outputs, where the input and output codes are different. if the no. of inputs and outputs are equal is greater than the no. of inputs.
Q.4 Ans
What is FLIP-FLOP? Name of all type of flip-flop. Explain R-S flip-flop? FLIP-FLOP- Flip-flop are the electronics device used in the digital world for a variety of fields. These are used to store data temporarily. to multiply or divide, to count operation, or to receive and transfer information when used properly. its bi-stable multi-vibrators. Types of flip-flop-: 1. 2. 3. 4. 5.
R-S flip flop J-K flip flop D flip flop T flip flop Master flip flop R-S flip flop-
Q.5 Ans
What is D flip flop. Explain with diagram?
Unit-IV
Q.1 What is R\2R ladder? Ans An R-2R Ladder is a simple and inexpensive way to perform digital-toanalog conversion, using repetitive arrangements of precision resistor networks in a ladder-like configuration. A string resistor ladder implements the non-repetitive reference network. R-2R resistor ladder network (digital to analog conversion, or DAC). A basic R-2R resistor ladder network is shown in Figure 1. Bit4 MSB (most significant bit) to Bit0 LSB (least significant bit) are driven from digital logic gates. Ideally, the bits are switched between 0 volts (digital 0) and Vref (digital 1). The R-2R network causes the digital bits to be weighted in their contribution to the output voltage Vout. In this circuit 5 bits are shown, giving 32 possible outputs. Depending on which bits are set to 1 and which to 0 the output voltage (out) will be a stepped value between 0 volts and (Vref minus the value of the minimum step, Bit0). For a digital value VAL, of a R-2R DAC of N bits of 0 V/Vref, the output voltage Vout is: Vout = Vref × VAL / 2N In the example shown, N = 5 and hence 2N = 32. With Vref = 3.3 V (typical CMOS logic 1 voltage), Vout will vary between 00000, VAL = 0 and 11111, VAL = 31. Minimum (single step) VAL = 1, we have Vout = 3.3 × 1 / 32 = 0.1 volts Maximum output (11111 VAL = 31, we have Vout = 3.3 × 31 / 25 = 3.2 volts The R-2R ladder is inexpensive and relatively easy to manufacture since only two resistor values are required (or 1, if R is made by placing a pair of 2R in parallel, or if 2R is made by placing a pair of R in series). It is fast and has fixed output impedance R.
The R-2R ladder operates as a string of current dividers whose output accuracy is solely dependent on how well each resistor is matched to the others. Small inaccuracies in the higher significant bit resistors can entirely overwhelm the contribution of the less significant bits. Q.2
Write the short notes on digital to analog conversion.
Ans
Figure 1: n-bit R-2R resistor ladder A basic R-2R resistor ladder network is shown in Figure 1. Bit a n-1 MSB (most significant bit) to Bit a0 LSB (least significant bit) are driven from digital logic gates. Ideally, the bits are switched between 0 volts (logic 0) and Vref (logic 1). The R-2R network causes the digital bits to be weighted in their contribution to the output voltage Vout. In this circuit 5 bits are shown (bits 4-0), giving (25) or 32 possible analog voltage levels at the output. Depending on which bits are set to 1 and which to 0, the output voltage (Vout) will be a corresponding stepped value between 0 volts and ( Vref minus the value of the minimum step, Bit0). The actual value of Vref (and 0 volts) will depend on the type of technology used to generate the digital signals. For a digital value VAL, of a R-2R DAC of N bits of 0 V/Vref, the output voltage Vout is: Vout = Vref × VAL / 2N In the example shown, N = 5 and hence 2N = 32. With Vref = 3.3 V (typical CMOS logic 1 voltage), Vout will vary between 00000, VAL = 0 and 11111, VAL = 31. Minimum (single step) VAL = 1, we have Vout = 3.3 × 1 / 32 = 0.1 volts Maximum output (11111) VAL = 31, we have
Vout = 3.3 × 31 / 25 = 3.2 volts The R-2R ladder is inexpensive and relatively easy to manufacture since only two resistor values are required (or 1, if R is made by placing a pair of 2R in parallel, or if 2R is made by placing a pair of R in series). It is fast and has fixed output impedance R. The R-2R ladder operates as a string of current whose output accuracy is solely dependent on how well each resistor is matched to the others. Small inaccuracies in the higher significant bit resistors can entirely overwhelm the contribution of the less significant bits. This may result in non-monotonic behavior at major crossings, such as from 01111 to 10000. Depending on the type of logic gates used and design of the logic circuits, there may be transitional voltage spikes at such major crossings even with perfect resistor values. These can be filtered, with capacitance at the output node for instance (the consequent reduction in bandwidth may be significant in some applications). Finally, the 2R resistance is in series with the digital output impedance. High output impedance gates (e.g., LVDS) may be unsuitable in some cases. For all of the above reasons (and doubtless others), this type of DAC tends to be restricted to a relatively small number of bits, although integrated circuits may push the number of bits to 14 or even more, 8 bits or fewer is more typical. Q.3
Explain Successive approximation ADC with block diagram?
Ans A successive approximation ADC is a type of analog-to-digital converter that converts a continuous analog waveform into a discrete digital representation via a binary search through all possible quantization levels before finally converging upon a digital output for each conversion. Block diagram
Successive Approximation ADC Block Diagram Key
DAC = Digital-to-Analog converter
EOC = end of conversion
SAR = successive approximation register
S/H = sample and hold circuit
Vin = input voltage
Vref = reference voltage
Q.3
Show the algorithm of Successive approximation ADC ?
Ans The successive approximation Analog to digital converter circuit typically consists of four chief sub circuits: 1. A sample and hold circuit to acquire the input voltage (Vin). 2. An analog voltage comparator that compares Vin to the output of the internal DAC and outputs the result of the comparison to the successive approximation register (SAR). 3. A successive approximation register sub circuit designed to supply an approximate digital code of Vin to the internal DAC. 4. An internal reference DAC that, for comparison with VREF, supplies the comparator with an analog voltage equal to the digital code output of the SARin. The successive approximation register is initialized so that the most significant bit (MSB) is equal to a digital 1. This code is fed into the DAC, which then supplies the analog equivalent of this digital code (V ref/2) into the comparator circuit for comparison with the sampled input voltage. If this analog voltage exceeds Vin the comparator causes the SAR to reset this bit; otherwise, the bit is left a 1. Then the next bit is set to 1 and the same test is done, continuing this binary search until every bit in the SAR has been tested. The resulting code is the digital approximation of the
sampled input voltage and is finally output by the conversion (EOC).
SAR at the end of the
Mathematically, let Vin = xVref, so x in [-1, 1] is the normalized input voltage. The objective is to approximately digitize x to an accuracy of n 1/2 . The algorithm proceeds as follows: 1. Initial approximation x0 = 0. 2. ith approximation xi = xi-1 - s(xi-1 - x)/2i.
where, s(x) is the sign-function(sign(x)) (+1 for x ≥ 0, -1 for x < 0). It follows using mathematical induction that |xn - x| ≤ 1/2n. As shown in the above algorithm, a SAR ADC requires: 1. An input voltage source Vin. 2. A reference voltage source V
ref
to normalize the input.
3. A DAC to convert the it approximation xi to a voltage. 4. A Comparator to perform the function s(xi - x) by comparing the DAC's voltage with the input voltage. 5. A Register to store the output of the comparator and apply xi-1 s(xi-1 - x)/2i.
Q.4
What is Charge-redistribution successive approximation ADC ?
Ans One of the most common implementations of the successive approximation ADC, the charge-redistribution successive approximation
ADC, uses a charge scaling DAC. The charge scaling DAC simply consists of an array of individually switched binary-weighted capacitors. The amount of charge upon each capacitor in the array is used to perform the aforementioned binary search in conjunction with a comparator internal to the DAC and the successive approximation register. 1. First, the capacitor array is completely discharged to the offset voltage of the comparator, VOS. This step provides automatic offset cancellation(i.e. The offset voltage represents nothing but dead charge which can't be juggled by the capacitors). 2. Next, all of the capacitors within the array are switched to the input signal, vIN. The capacitors now have a charge equal to their respective capacitance times the input voltage minus the offset voltage upon each of them. 3. In the third step, the capacitors are then switched so that this charge is applied across the comparator's input, creating a comparator input voltage equal to -vIN. 4. Finally, the actual conversion process proceeds. First, the MSB capacitor is switched to VREF, which corresponds to the full-scale range of the ADC. Due to the binary-weighting of the array the MSB capacitor forms a 1:1 charge divider with the rest of the array. Thus, the input voltage to the comparator is now -vIN plus VREF/2. Subsequently, if vIN is greater than VREF/2 then the comparator outputs a digital 1 as the MSB, otherwise it outputs a digital 0 as the MSB. Each capacitor is tested in the same manner until the comparator input voltage converges to the offset voltage, or at least as close as possible given the resolution of the DAC. Q.5 Use with non-ideal analog circuits? Ans When implemented as an analog circuit - where the value of each successive bit is not perfectly 2^N (e.g. 1.1, 2.12, 4.05, 8.01, etc.) - a successive approximation approach might not output the ideal value because the binary search algorithm incorrectly removes what it believes to be half of the values the unknown input cannot be. Depending on the difference between actual and ideal performance, the maximum error can easily exceed several LSBs, especially as the error between the actual and ideal 2^N becomes large for one or more bits. Since we don't know the actual unknown input, it is therefore very important that accuracy of the analog circuit used to implement a SAR A
Since we know that binary count sequences follow a pattern of octave (factor of 2) frequency division, and that J-K flip-flop multivibrators set up for the "toggle" mode are capable of performing this type of frequency division, we can envision a circuit made up of several J-K flip-flops, cascaded to produce four bits of output. The main problem facing us is to determine how to connect these flipflops together so that they toggle at the right times to produce the proper binary sequence. Examine the following binary count sequence, paying attention to patterns preceding the "toggling" of a bit between 0 and 1:
UNIT-V
Q.1
What is microprocessor ?
Ans Microprocessor is a computer processor that incorporates the functions of a computer's central processing unit (CPU) on a single integrated circuit (IC), or at most a few integrated circuits. [2] The microprocessor is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and provides results as output. It is an example of sequential digital logic, as it has internal memory. Microprocessors operate on numbers and symbols represented in the binary numeral system. The integration of a whole CPU onto a single chip or on a few chips greatly reduced the cost of processing power. The integrated circuit processor was produced in large numbers by highly automated processes, so unit cost was low. Single-chip processors increase reliability as there are many fewer electrical connections to fail. As microprocessor designs get faster, the cost of manufacturing a chip (with smaller components built on a semiconductor chip the same size) generally stays the same. Before microprocessors, small computers had been implemented using racks of circuit boards with many medium- and small-scale integrated circuits. Microprocessors integrated this into one or a few large-scale ICs. Continued increases in microprocessor capacity have since rendered other forms of computers almost completely obsolete (see history of computing hardware), with one or more microprocessors used in everything from the smallest embedded systems and handheld devices to the largest mainframes and supercomputers. Q.2) Show pin diagram of 8086 microprocessor?
1
9
1
Intel 8086 registers (bit position)
1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
Main registers AH BH CH DH Index registers 0000 0000 0000 0000 Program counter 0000 Segment registers CS DS ES SS Status register - - - - OD I
Q.3
AL BL CL DL
AX (primary accumulator) BX (base, accumulator) CX (counter, accumulator) DX (accumulator, other functions)
SI DI BP SP
Source Index Destination Index Base Pointer Stack Pointer
IP
Instruction Pointer 0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
Code Segment Data Segment ExtraSegment Stack Segment
T S Z - A - P - C Flags
Explain addressing modes of 8086?
Ans In computer programming, addressing modes are primarily of interest to compiler writers and to those who write code directly in assembly language. Immediate Mode
The immediate mode is the simplest form of addressing. The operand is part of the instruction and therefore no memory reference, other than the instruction, is required to retrieve the operand. This fast mode is used to define constants or set initial variable values. Immediate mode has a limited range because it is restricted to the size of the address field, which for most instruction sets is small compared to word length.
Direct Mode
In direct mode, the address field contains the address of the operand. It requires a single memory reference to read the operand from the given location. However, direct mode provides only limited address space.
Indirect Mode
Indirect mode address fields contain the operand's address pointer, which in turn contains the full-length address of the operand. Unlike direct and immediate addressing, indirect mode has a large address space but is slower because multiple memory access is required to find the operand.
Register Mode
Register mode is similar to direct mode. The key difference between the two modes is that the address field of the instruction refers to a register rather than a memory location. Register addressing does not have an effective address -- three or four bits are used as the address field to reference registers.
Register Indirect Mode
Similar to indirect addressing, in this mode the operand is inside a memory cell pointed to by contents of a register. The register contains the effective address of the operand. This mode has a large address
space, but it's limited to the width of the registers available to store the effective address. Displacement Mode
Displacement mode consists of three variations: relative addressing; base register addressing; and indexing addressing. This mode can be considered a combination of direct and register indirect addressing. The address holds two values -- base value and a register that contains an integer displacement that is added or subtracted from the base to form the effective address in memory.
Stack Mode
Q.4
Stack mode, also known as implicit addressing, consists of a linear array of locations referred to as last-in first-out queue. The operand is on the top of the stack. The stack pointer is a register that stores the address of top of stack location. Distinguish between the serial port and parallel port of IBM?
Ans A serial port is a serial communication physical interface through which information transfers in or out one bit at a time. Throughout most of the history of personal computers, data was transferred through serial ports to devices such as modems, terminals and various peripherals. While such interfaces as Ethernet, FireWire, and USB all send data as a serial stream, the term "serial port" usually identifies hardware more or less compliant to the RS-232 standard, intended to interface with a modem or with a similar communication device. Modern computers without serial ports may require serial-to-USB converters to allow compatibility with RS 232 serial devices. Serial ports are still used in applications such as industrial automation systems, scientific instruments, point of sale systems and some industrial and consumer products. Server computers may use a serial port as a control console for diagnostics. Network equipment (such as routers and switches) often use serial console for configuration. Serial ports are still used in these areas as they are simple, cheap and their console functions are highly standardized and widespread. A serial port requires very little supporting software from the host system. a serial port is a serial communication physical interface through which information transfers in or out one bit at a time. Throughout most of the history of personal
computers, data was transferred through serial ports to devices such as modems, terminals and various peripherals.
A parallel port is a type of interface found on computers (personal and otherwise) for connecting peripherals. In computing, a parallel port is a parallel communication physical interface. It is also known as a printer port or Getronics port. It was an industry de facto standard for many years, and was finally standardized as IEEE 1284 in the late 1990s, which defined a bi-directional version of the port. Today, the parallel port interface is seeing decreasing use because of the rise of Universal Serial Bus (USB) devices, along with network printing using Ethernet. The parallel port interface was originally known as the Parallel Printer Adapter on IBM PC-compatible computers. It was primarily designed to operate a line printer that used IBM's 8-bit extended ASCII character set to print text, but could also be used to adapt other peripherals. Graphical printers, along with a host of other devices, have been designed to communicate with the system. Q.5
Show the architecture of the 8086 microprocessor.
Ans
8086 employ parallel processing.
8086 contain two processing unit-the bus interface unit and execution unit.
The bus interface unit is the path that 8086 connects to external devices.
The system bus includes an 8-bit bidirectional data bus for 8086(16 bits for the 8088), a 20-bit address bus, and the signal needed to control transfers over the bus.
Components in BIU
Segment register
The instruction pointer
Address generation adder bus control logic instruction queue
Components in EU
Arithmetic logic unit, ALU
Status and control flags
General-purpose registers
Temporary-operand registers
