Half adder is used to perform the addition of 2 bits using combinational circuit. input variables are augend and addend bits and output variables are sum & carry bits.
| A | B | Sum | Carry |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 0 | 1 | 1 | 0 |
| 1 | 0 | 1 | 0 |
| 1 | 1 | 0 | 1 |
Full Adder adds three inputs and produces two outputs. first two inputs are A and B and third input is carried input denoted as C-IN. The output carry is defined as C-OUT and normal output is defined as S which is SUM.
A full adder logic is designed in such manner that can take eight inputs together to create byte-wide adder and cascade carry bit from one adder to another.
Applications of multiplexer are as follows:
- Used in time-multiplexing system.
- It is used as A/D to D/A Converter.
- Used in data acquisition system
- It is used as data selector.
The applications of the demultiplexer are as follows:
- It is used as decoder for the conversion of binary to decimal.
- It is used as serial-to-parallel converter.
- Used in the data transmission system for error detection.
Rise time: Time required to change the voltage level from 10% to 90%.
Fall time: Time that is required to change voltage level from 90% to 10%.
Hold Time: Lowest time at which voltage level becomes constant after triggering clock pulse to clock into the flip flop reliably is known as Hold time. It is denoted by t(hold).
Setup time: The minimum time required to maintain constant voltage levels at excitation inputs of flip-flop device before triggering edge of the clock pulse reliably clocked in the flip-flop is called the Setup time. It is denoted as setup.
| NO. | Synchronous Counter | Asynchronous Counter |
|---|---|---|
| 1 | All flip-flops are triggered with the same clock simultaneously. | Different flip-flops are triggered with different clocks, not simultaneously. |
| 2 | A synchronous Counter is faster than an asynchronous counter in operation. | The asynchronous Counter is slower than the synchronous counter in operation. |
| 3 | Also known as Parallel Counter. | Also known as Serial Counter. |
| 4 | In synchronous counter, propagation delay is less. | In the asynchronous counter, there is a high propagation delay. |
One hot encoding is used in the process of categorizing data variables to be used in machine learning algorithms for making better predictions. In one-hot encoding, we convert each categorical value into a different column, and in return, it gives a binary value, either 0 or 1 to each column. And each integer value represents a binary vector.
Content addressable memory (CAM) is data storage device, that stores memory in cells. When any data is entered into memory, CAM compares input with all stored data. It is high-speed technology. In CAM, memories are unsorted, which means they are not arranged in chronological order and are not packed in isolated modules.
A Register is used to store information. register is group of flip-flops that are connected in series and used to store multiple bits of data. The information stored within registers can be transferred with the help of shift registers. Shift Register is also group of flip-flops that is used to store multiple bits of data. bits stored in shift registers can be moved within the registers and in/out of the registers by using clock pulses. n-bit shift register can be obtained by joining n flip-flops.
The registers that will shift the bits to the right are called "Shift right registers". The registers that will shift the bits to the left are called "Shift left registers".
Shift registers are basically of 4 types:
- Parallel In parallel Out shift register
- Parallel In Serial Out shift register
- Serial In Serial Out shift register
- Serial In parallel Out shift register
A ring counter is a typical application of the Shift register. The ring counter is almost the same as the shift counter. The only change is that the output of the last flip-flop is connected to the input of the first flip-flop in the case of the ring counter but in the case of the shift register it is taken as output. Except for this, all the other things are the same. (No. of states in Ring counter = No. of flip-flop used)
So, for designing a 4-bit Ring counter we need 4 flip-flops.
Scrambling is a technique that does not increase the number of bits and does provide synchronization. The problem with techniques like Bipolar AMI(Alternate Mark Inversion) is that continuous sequences of zeroes create synchronization problems one solution to this is Scrambling.
There are two common scrambling techniques:
- B8ZS(Bipolar with 8-zero substitution)
- HDB3(High-density bipolar3-zero)
| NO. | Combinational Circuits | Sequential Circuits |
|---|---|---|
| 1 | These are faster in speed. | These are slower. |
| 2 | These are easy to design. | These are difficult to design. |
| 3 | The clock input is not required. | The clock input is required. |
| 4 | In this, the memory units are not required. | In this, the memory units are required to store the previous values of inputs. |
| 5 | Example: Mux, Demux, encoder, decoder, adders, subtractors. | Example: Shift registers, counters. |
Rise time is the time that is required to change the voltage level from 10% to 90%.
Fall time is the time that is required to change the voltage level from 90% to 10%.
The minimum time that is required to maintain the constant voltage levels at the excitation inputs of the flip-flop device before the triggering edge of the clock pulse for the levels to be reliably clocked in the flip flop is called the Setup time. It is denoted as setup.
- Buffer helps to introduce small delays.
- Buffer helps for high Fan-out.
- Buffer are used to eliminate cross talks.
An ideal diode is a two terminal polarity sensitive device that has zero resistance when it is forward biased and infinite resistance when reverse biased.
Reverse current of a diode is due to minority carriers and is caused when the diode is reverse biased. Only a very small voltage is required to direct all minority carriers across the junction, and when all minority carriers are flowing across, further increase in bias voltage will not cause increase in current. This current is referred to as reverse saturation current.
The static or dc resistance of a diode is the resistance offered by it to the direct current. It is defined as the ratio of the diode voltage and current at the point of interest and is not sensitive to the shape of the V-I characteristic curve. It decreases with the increase in diode current or voltage.
The AND gate truth table is for the two fan-in or inputs, A and B. It has only one output as Y. The output is logic '0' if any inputs A and B are LOW (logic '0'). However, the output is 1 only when all the inputs are 1.
| A | B | Y |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
An OR gate can have two or more inputs, with at least one being true. The bits are set to one using the OR operator. The truth table for the OR gate is shown below:
| A | B | Y |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
A NAND gate ("not AND gate") is a logic gate that produces a low output (0) only if all its inputs are true, and high output (1) otherwise. Hence the NAND gate is the inverse of an AND gate, and its circuit is produced by connecting an AND gate to a NOT gate. Just like an AND gate, a NAND gate may have any number of input probes but only one output probe.
| A | B | Y |
|---|---|---|
| 0 | 0 | 1 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
| X-OR Gate | X-NOR Gate |
|---|---|
| It is termed as "Exclusive OR Gate". | It is termed as "Exclusive NOR Gate". |
| Similar to OR Gate | Similar to XOR Gate with a NOT Gate added |
| Boolean expression: AB' + A'B or A⊕B | Boolean expression: AB + A'B' or A ⊙ B |
| Returns true when odd number of inputs are true | Returns true only when both the inputs are equal |
A race condition in digital circuits is a situation where the outcome depends on the order in which events occur. It can also be defined as a situation where a system's behaviour depends on the timing or sequence of other events that are not controllable.
Fixed resistors have a constant resistance value that cannot be changed. The resistance provided by a fixed resistor is also constant. The resistance of a fixed resistor is measured in ohms, represented by the symbol Ω.
Variable resistors can have their resistance adjusted. They can change their value as the current changes. Variable resistors are commonly used as volume controls.
A capacitor is an electronic device that stores electrical energy in an electric field by accumulating electric charges on two closely spaced surfaces that are insulated from each other. It is a passive electronic component with two terminals.
The effect of a capacitor is known as capacitance. While some capacitance exists between any two electrical conductors in proximity in a circuit, a capacitor is a component designed to add capacitance to a circuit. The capacitor was originally known as the condenser.
An inductor is a passive electronic component that stores energy in a magnetic field when current passes through it. Inductors are used in many switched-mode power supplies to produce DC current.
Here are some purposes of inductors in a circuit:
- Store energy: Inductors store energy in the form of a magnetic field. This energy is used to maintain current flow during switching periods.
- Resist current changes: Inductors oppose changes in the amount of current flowing through them.
- Enable higher output voltage: Inductors enable topographies where the output voltage is higher than the input voltage.
A semiconductor diode is a two-terminal electronic component that allows current to pass in one direction, while blocking it in the other. The two terminals are an anode (positive side) and a cathode (negative side). The basic operation of a diode is called rectification. Whether current flows or not depends on the direction of voltage applied to the terminals.
Forward biasing: Putting a voltage across a diode that allows current to flow easily
Reverse biasing: Putting a voltage across a diode in the opposite direction
| BJT | FET |
|---|---|
| BJT stands for bipolar junction transistor, so it is a bipolar component. | FET stands for the field-effect transistor, so it is a uni-junction transistor |
| BJT has three terminals like base, emitter, and collector. | FET has three terminals like Drain, Source, and Gate. |
| The operation of BJT mainly depends on both the charge carriers like majority as well as minority | The operation of FET mainly depends on the majority charge carriers either holes or electrons |
| The input impedance of this BJT ranges from 1K to 3K, so it is very less. | The input impedance of FET is very large |
| BJT is the current controlled device | FET is the voltage-controlled device |
Emitter: Emitter terminal is the heavily doped region as compared two base and collector. This is because the work of the emitter is to supply charge carrier to the collector via the base. The size of the emitter is more than base but less than the collector.
Base: The size of the base region is extremely small, it is less than emitter as well as the collector. The size of the base is always kept small so that charge carriers coming from the emitter and entering base will not recombine in the base region and will be directed towards the collector region. The doping intensity of base is also less than emitter and collector for the same reason mentioned above.
Collector: The collector terminal is moderately doped, and the size of the collector region is slightly more than emitter region because all the charge carriers coming from the emitter recombine at base and heat is released in this process. Thus, it is necessary for the collector terminal to be large enough so that it can dissipate the heat and the device may not burn out.
In some applications the amount of input current available to switch on a transistor is very low. This may mean that a single transistor may not be able to pass sufficient current required by the load. As stated earlier this equals the input current x the gain of the transistor (hFE). If it is not possible to increase the input current then the gain of the transistor will need to be increased. This can be achieved by using a Darlington Pair.
A dual in-line package (DIP) is a through-hole package that's used for integrated circuits in PCBs. The DIP's design ensures a reliable connection between the component and the PCB or cable. This allows for reliable data transmission.
A transformer is a passive electrical component that changes the voltage of electricity in an electronic circuit. It can increase the voltage (step up) or decrease the voltage (step down). Transformers are necessary because the voltage requirements of different appliances can vary.
| No. | Step-up Transformer | Step-down Transformer |
|---|---|---|
| 1 | The number of turns in its secondary is more than that in its primary (NS > NP). | The number of turns in primary is greater than secondary (NP > NS). |
| 2 | The alternating voltage across the ends of its secondary is more than that across its primary i.e., eS > eP | The alternating voltage across the ends of the primary is more than that across its secondary i.e., eP > eS |
| 3 | Transformer ratio K > 1. | Transformer ratio K < 1. |
| 4 | Primary coil made of thick wire. | Secondary coil made of thick wire. |
A rectifier converts alternating current (AC) to direct current (DC). This process is called rectification.
Rectifiers are used in power supply circuits to power appliances. Most electrical appliances use a DC power supply. Many power supplies, like standard electrical output, produce AC voltage.
Rectifiers also charge batteries and keep them in good condition. They also provide DC power for other loads.
Rectifiers work by allowing current to flow through the device in one direction only. Diodes act like one-way valves to maintain this flow of current.
A voltage regulator is a circuit that creates and maintains a fixed output voltage, irrespective of changes to the input voltage or load conditions. Voltage regulators (VRs) keep the voltages from a power supply within a range that is compatible with the other electrical components. While voltage regulators are most commonly used for DC/DC power conversion, some can perform AC/AC or AC/DC power conversion as well.
| PARAMETERS | LINEAR POWER SUPPLY | SWITCH MODE POWER SUPPLY (SMPS) |
|---|---|---|
| Definition | It completes the stepping down of AC voltage first then it converts it into DC | It converts the input signal into DC first then it steps down the voltage up to desired level. |
| Efficiency | Low efficiency i.e. about 20-25% | High Efficiency i.e. about 60-65% |
| Voltage Regulation | Voltage regulation is done by voltage regulator. | Voltage regulation is done by feedback circuit. |
| Complexity | Less complex than SMPS. | More complex than Linear power supply. |
| Transient response | It possess faster response. | It possess slower response. |
Power dissipation is the process of losing power in the form of heat. It's a natural process that occurs in all resistors that have a voltage drop across them. In a circuit, power dissipation is a measurement that quantifies how much heat is released due to inefficiencies. It's also a measure of how much power in a circuit is converted into heat. According to Ohm's law, when an electric current passes through a resistor, a voltage drop occurs across its end. This means that some electric potential energy is lost when the electric charge moves from one end of the resistor to the other.
Schottky diodes have high switching speeds and high-frequency capabilities, which make them well-equipped for use in radio frequency applications. Additionally, Schottky diodes have various metal-semiconductor junction configurations, making these semiconducting devices useful in power detector or mixer circuits.
An operational amplifier (op-amp) can function as a comparator because it has a high gain and a differential input stage. The output of an op-amp will "rail" to its maximum or minimum value if one input is higher than the other. This application is often called a comparator circuit. An op-amp comparator compares two analog voltage levels or an analog voltage level with a preset reference voltage. It produces an output signal based on this voltage comparison.
Light-emitting diode (LED) is a widely used standard source of light in electrical equipment. It has a wide range of applications ranging from your mobile phone to large advertising billboards. They mostly find applications in devices that show the time and display different types of data.
In digital electronics, a decoder converts digital signals to analog signals. It has n lines as input, and a maximum of 2n lines as output. The output lines define the 2N-bit code for the binary information.A decoder is a combinational circuit that converts N inputs into 2N outputs. It's the opposite of an encoder, which converts 2N inputs to N outputs.
A multiplexer is used to combine multiple input signals into a single output. This allows several input signals to share one device or resource. Multiplexers are used in many applications, including:
- Data routing
- Data transmission
- Signal processing
- Digital systems design
- Boolean functions of multiple variables
A voltage logic level defines the voltage to represent a logic high or a logic low. Many circuits represent a logic high by +5 V or +3.3 V to ground and a logic low as ground or 0 V. This type of system is called a positive or active-high.
A Counter is a device which stores (and sometimes displays) the number of times a particular event or process has occurred, often in relationship to a clock signal. Counters are used in digital electronics for counting purpose, they can count specific event happening in the circuit. For example, in UP counter a counter increases count for every rising edge of clock. Not only counting, a counter can follow the certain sequence based on our design like any random sequence 0,1,3,2…. They can also be designed with the help of flip flops. They are used as frequency dividers where the frequency of given pulse waveform is divided. Counters are sequential circuit that count the number of pulses can be either in binary code or BCD form. The main properties of a counter are timing , sequencing , and counting. Counter works in two modes
- Up counter
- Down counter
A 4-bit binary adder is a fundamental electronic circuit used to do addition operations. The adder takes two 4-bit inputs, A and B to produce a 4-bit output, sum along with a carry out. This means you can calculate 1111+1111, which will give you 11110 ( 15+15 = 30).
A decoder is a combinational logic circuit that changes the format of an encrypted input stream. A demultiplexer is a combination circuit that routes a single input signal into one of many output signals
Binary code is the foundation of all computing systems and operations. It allows computers to store and manipulate data using a system of switches that can be turned on or off. These switches are represented by the digits 0 and 1.Binary code is used to represent all instructions and data in a digital computer system. This includes:
- Text, Numbers, Images, Sound, Video, Audio, Formulas.
A shift register is a digital circuit that stores and moves data. It's made up of a series of flip-flops, where the output of one flip-flop is connected to the input of the next. The shift register shares a single clock signal that controls the movement of data.
When the clock signal changes from low to high, the data is moved from one stage to the next. This is known as a "clock pulse".
| PARAMETER | RING COUNTER | JOHNSON COUNTER |
|---|---|---|
| Application | Ring counter is mostly used in successive approximation type ADC and stepper motor control. | Johnson counter is also referred to as walking counter or switching tail counter and is mostly used in phase shift or function generator. |
| Output | In ring counter, the output of the last flip flop is connected to the input of the first flip flop. | In Johnson counter, the output bar or Q-bar of the last flip flop is connected to the input of the first flip flop. |
| Decoding | Decoding is easy in ring counter as the number of states is equal to the number of flip flops. | Decoding the Johnson counter is complex as compared to ring to counter. |