What is abrupt varactor diode?
Abrupt varactor diodes As the abruptness of the junction is governed by the doping concentration and also the profile, this is controlled during the manufacture. For an abrupt varactor diode the doping concentration is held constant, i.e constant doping level as far as reasonably possible.
In which of the following applications varactor diode can be used?
Varactor diode is commonly used for Electronic tuning.
What is the use of Varacter diode in radio receiver?
Varactor diodes are mainly used in Voltage Controlled Oscillators (VCOs) and RF Filters for tuning the receiver to the incoming signal or different stations.
What is an abrupt pn junction?
An abrupt junction is by definition a junction in which the doping type changes over a very small distance compared to the spatial extent of the depletion region (see below.) Figure EC1 : Donor and acceptor density profiles in an abrupt PN junction.
What is difference between ordinary diode and varactor diode?
In a normal PN junction diode, doping impurities are usually dispersed equally throughout the material. Varactor diode doped with a very small quantity of impurities near the junction and impurity concentration increases moving away from the junction.
What is the advantage of Superheterodyning?
The superheterodyne receiver offers superior sensitivity, frequency stability and selectivity. Compared with the tuned radio frequency receiver (TRF) design, superhets offer better stability because a tuneable oscillator is more easily realized than a tuneable amplifier.
What is fidelity of a receiver?
Fidelity of a receiver is its ability to reproduce the exact replica of the transmitted signals at the receiver output. In other words, the fidelity of a receiver is its ability to accurately reproduce, in its output, the signal that appears at its input.
What is the forward bias?
Forward bias or biasing is where the external voltage is delivered across the P-N junction diode. In a forward bias setup, the P-side of the diode is attached to the positive terminal and N-side is fixed to the negative side of the battery. Here, the applied voltage is opposite to the junction barrier potential.
What is depletion approximation?
Depletion approximation: An idealization of the actual charge distribution in the depletion region that originates from the fact that the majority carriers have been removed. We say this region is “depleted” of majority carriers. It facilitates the use of Poisson’s equation because we can obtain a closed-form solution.
Abrupt varactor diode exhibits the inverse square of the C-V function and the doping concentration is constant. What is a hyper abrupt varactor diode? Hyperabrupt varactor diode is used as it has greater capacitance for the given change of voltage.
What are varactor diodes and how do they work?
Varactor diodes are mostly operated under reverse bias conditions and therefore, there is no conduction. They are voltage controlled capacitors and sometimes known as varicap diodes, although the word varactor is widely used.
What are the disadvantages of a varactor diode?
There is one disadvantage if we use one varactor diode in circuitry such as radio frequency then during forward biasing through the radio signal frequency leakage current will increase for a short time interval. The harmonic distortion is created if a diode is consecutively biased positively and negatively.
What does the gap between the plates of a varactor diode show?
The gap between the plates shows their dielectric. The function of the varactor diode is to store charges, so it is always operated in reverse bias condition. When a forward bias voltage is applied, the electric current flows, as a result, the depletion region becomes negligible, which is undesirable.