Definition: A Digital Comparator is a combinational logic circuit that is used for comparison of two binary values. Basically it generates the desired signal (either low or high) at the output when compares two digital values provided at its input. We all know that combinational circuits (like adder and subtractor) produce addition and subtraction of binary values present at the input terminals. But, along with addition and subtraction, some applications require a comparison of two values … [Read more...] about Digital Comparator – Magnitude and Identity Comparator
Phase-Locked Loops (PLL)
Definition: Phase-locked loops are the circuits used to maintain synchronization between input and output frequency of oscillator circuits by comparing the difference in phase of the two signals. With the evolution of IC, it has emerged as the basic building block of electronic circuits. Phase-locked loops are abbreviated as PLL and are basically a feedback circuit comprising of a phase detector (or comparator), a low pass filter and voltage-controlled oscillator along with an … [Read more...] about Phase-Locked Loops (PLL)
Synchronous Counter
Definition: The synchronous counter is a type of counter in which the clock signal is simultaneously provided to each flip-flop present in the counter circuit. More specifically, we can say that each flip-flop is triggered in synchronism with the clock input. Unlike asynchronous counter where separate clock pulses are used to trigger the flip-flop, all the flip-flops in synchronous counters are triggered using a single clock pulse. We know designing an asynchronous counter is easy then … [Read more...] about Synchronous Counter
Asynchronous Counter
Definition: Asynchronous counters are those counters which do not operate on simultaneous clocking. In asynchronous counter, only the first flip-flop is externally clocked using clock pulse while the clock input for the successive flip-flops will be the output from a previous flip-flop. This means that only a single clock pulse is not driving all the flip-flops in the arrangement of the counter. Asynchronous counters are also known as ripple counters and are formed by the successive … [Read more...] about Asynchronous Counter
Companding
Definition: Companding is a technique of achieving non-uniform quantization. It is a word formed by the combination of words compression and expanding. Companding is done in order to improve SNR of weak signals. We know if the characteristics of the quantizer is non-linear then it causes the step size to be variable despite being constant then it is known as non-uniform quantization. As we know in non-uniform quantization, the step size varies according to the signal level.If the signal … [Read more...] about Companding
Wavelength Division Multiplexing (WDM)
Definition: WDM is a short form used for Wavelength Division Multiplexing. It is a technique in which signals of different wavelength are multiplexed together in order to get transmitted over an optical link. The concept of WDM was arrived in 1970. It is an analog multiplexing technique used in fiber optic communication. Here, optical signals of multiple wavelengths are transmitted using a fiber link. Basically, the technique acts in a way that signals get combined using a multiplexer … [Read more...] about Wavelength Division Multiplexing (WDM)
Beat Frequency Oscillator (BFO)
Definition: Beat Frequency Oscillator or BFO is an oscillator that produces a sinusoidal signal of the variable audio frequency range. It provides such a frequency that can be varied over a very large range. BFO was invented in 1901 by Reginald Fessenden. It is among the most common type of oscillator that can generate a signal of variable frequency at its output. Block Diagram and Working of Beat Frequency Oscillator The figure below represents the block diagram of a BFO:Here as we can … [Read more...] about Beat Frequency Oscillator (BFO)
Phase Shift Oscillator
Definition: Phase shift oscillators are the oscillators that generate a stable sinusoidal signal at the output. Basically, the circuit has, an amplifier unit like transistor or op-amp along with a feedback network comprising of resistors and capacitors. Thus, is also known as RC phase shift oscillator. The RC network is present in the feedback path is connected in ladder fashion thus also known as ladder RC phase shift oscillator. We know for an RC circuit; the output voltage leads the input … [Read more...] about Phase Shift Oscillator
Zero Crossing Detector
Definition: An op-amp detector that has the ability to detect the change from positive to negative or negative to a positive level of a sinusoidal waveform is known as a zero crossing detector. More specifically, we can say that it detects the zero crossing of the applied ac signal. It is basically a voltage comparator whose output changes when the input signal crosses the zero of the reference voltage level. Thus it is named so. It is also known to be a square wave generator as the … [Read more...] about Zero Crossing Detector
Relaxation Oscillator
Definition: A relaxation oscillator is basically a non-linear oscillator that has the ability to generate a non-sinusoidal periodic waveform at its output. Such as triangular wave, square wave etc. These are also known as non-sinusoidal waveform generators. A relaxation oscillator operates in such a way that it generates oscillations by charging the capacitor and quickly discharging it after attaining a pre-determined threshold voltage. The figure below will help you to understand the … [Read more...] about Relaxation Oscillator