Resonant frequency of a circuit is proportional to sq rt (L x C). A varactor diode, when suitably voltage biased, looks like a capacitor (C). Varying the bias varies the capacitor and thus the resonant frequency .
YES
A varactor modulator uses a varactor diode, which changes its capacitance with varying voltage, to modulate signals, typically in frequency modulation applications. In contrast, a reactance modulator alters the reactance of a circuit using various components (like capacitors or inductors) to achieve modulation, often in amplitude modulation schemes. While both techniques modify the reactive properties of a circuit to achieve modulation, the varactor modulator specifically relies on the tunable capacitance of the varactor diode for its operation.
I think you you are asking about varactor diode. varactor means variable capacitor. varactor diode is a p-n junction diode which provide a capacitance across it subjected to applied forward and reverse bias. means it provide variable capacitance which depends on the applied reverse voltage(mostly varactor diode works on reverse voltage).They are also known as varicap
The varactor diode is used in frequency tuning applications. Its effective capacitance is a function of the reverse bias voltage across it.
The capacitance of a varactor diode can be changed by varying the reverse bias voltage applied across it. As the reverse voltage increases, the depletion region widens, which reduces the capacitance. Conversely, decreasing the reverse bias voltage narrows the depletion region, increasing the capacitance. This property allows varactor diodes to be effectively used in tuning applications, such as in voltage-controlled oscillators.
YES
A varactor modulator uses a varactor diode, which changes its capacitance with varying voltage, to modulate signals, typically in frequency modulation applications. In contrast, a reactance modulator alters the reactance of a circuit using various components (like capacitors or inductors) to achieve modulation, often in amplitude modulation schemes. While both techniques modify the reactive properties of a circuit to achieve modulation, the varactor modulator specifically relies on the tunable capacitance of the varactor diode for its operation.
I think you you are asking about varactor diode. varactor means variable capacitor. varactor diode is a p-n junction diode which provide a capacitance across it subjected to applied forward and reverse bias. means it provide variable capacitance which depends on the applied reverse voltage(mostly varactor diode works on reverse voltage).They are also known as varicap
A diode modulator is a type of AM modulator constructed using diodes. One type of diode modulator is the ring modulator shown in the image.
varactor diode is a correct answer
A diode bridge modulator is one kind of balanced modulator.
invented by Arthur Uhlir and A. Bakanowski
the output from a balanced modulator consists of modulating freq also. this can be eliminated in a diode modulator by adding two more diodes, making a diode ring. therefore called ring modulator
the output from a balanced modulator consists of modulating freq also. this can be eliminated in a diode modulator by adding two more diodes, making a diode ring. therefore called ring modulator
hello
It is called a varactor or a varicap diode. Its capacitance varies nonlinearly with the reverse voltage applied to its terminals.
Short answer: By using a varactor diode as the capacitance in a parallel resonant ckt, by changing the reverse bias voltage you change the value of capacitance which in turn changes the resonant frequency. This makes a tuneable resonant ckt.