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An active-filter tuned oscillator is an active electronic circuit designed to produce a periodic signal. It consists of a bandpass filter and an active amplifier, such as an OP-AMP or a BJT. The oscillator is commonly tuned to a specific frequency by varying the reactant of the feedback path within the circuit. An example is the Colpitts ...
Single transistor emitter-follower circuit. The Butler oscillator is a crystal-controlled oscillator that uses the crystal near its series resonance point. They are used where a simple low-cost circuit is needed which can oscillate at high frequencies (>50MHz [1]) by using overtones of a crystal, and also giving low phase noise.
Tuning the receiver involves changing the frequency of the local oscillator, with further processing of the signal (especially in relation to increasing the receiver) conveniently done at a single frequency (the IF frequency) thus requiring no further tuning for different stations. A schematic of a superhet AM receiver. Note that the radio ...
Hartley oscillator using a common-drain n-channel JFET instead of a tube.. The Hartley oscillator is distinguished by a tank circuit consisting of two series-connected coils (or, often, a tapped coil) in parallel with a capacitor, with an amplifier between the relatively high impedance across the entire LC tank and the relatively low voltage/high current point between the coils.
Clock outputs are "pullable," i.e., their frequency can be "pulled" or fine-tuned. VCXO outputs can be pulled using an analog voltage input. TCXO – Temperature Compensated Oscillator and VC-TCXO – Voltage Controlled TCXO 0.5–5 ppm High-performance equipment that requires very stable frequencies: networking; base stations; femtocells ...
A blocking oscillator (sometimes called a pulse oscillator) is a simple configuration of discrete electronic components which can produce a free-running signal, requiring only a resistor, a transformer, and one amplifying element such as a transistor or vacuum tube.
Tuning gain and noise present in the control signal affect the phase noise; high noise or high tuning gain imply more phase noise. Other important elements that determine the phase noise are sources of flicker noise (1/f noise) in the circuit, [8] the output power level, and the loaded Q factor of the resonator. [9] (see Leeson's equation).
Circuit symbol of a heptode. The development of the pentagrid or heptode (seven-electrode) valve was a novel development in the mixer story. The idea was to produce a single valve that not only mixed the oscillator signal and the received signal and produced its own oscillator signal at the same time but, importantly, did the mixing and the oscillating in different parts of the same valve.