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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.
Fig. 1 shows the common-base Colpitts circuit. The inductor L and the series combination of C 1 and C 2 form the resonant tank circuit, which determines the frequency of the oscillator. The voltage across C 2 is applied to the base-emitter junction of the transistor, as feedback to create oscillations. Fig. 2 shows the common-collector version.
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 ...
A basic Direct Digital Synthesizer consists of a frequency reference (often a crystal or SAW oscillator), a numerically controlled oscillator (NCO) and a digital-to-analog converter (DAC) [5] as shown in Figure 1. The reference oscillator provides a stable time base for the system and determines the frequency accuracy of the DDS.
VCOs can be generally categorized into two groups based on the type of waveform produced. [4]Linear or harmonic oscillators generate a sinusoidal waveform. Harmonic oscillators in electronics usually consist of a resonator with an amplifier that replaces the resonator losses (to prevent the amplitude from decaying) and isolates the resonator from the output (so the load does not affect the ...
YIG filters tuned by a sweep current are used in spectrum analyzers. Another YIG application is YIG oscillators , where the sphere acts as a tunable frequency-determining element. It is coupled to an amplifier which provides the required feedback for oscillation.
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.
A variable frequency oscillator (VFO) in electronics is an oscillator whose frequency can be tuned (i.e., varied) over some range. [1] It is a necessary component in any tunable radio transmitter and in receivers that work by the superheterodyne principle. The oscillator controls the frequency to which the apparatus is tuned.