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A Colpitts oscillator, ... where is the transconductance of the transistor. The input current is given by =, where is the impedance of . Solving for ...
Edwin Henry Colpitts (January 19, 1872 – March 6, 1949) was a communications pioneer best known for his invention of the Colpitts oscillator.As research branch chief for Western Electric in the early 1900s, he and scientists under his direction achieved significant advances in the development of oscillators and vacuum tube push–pull amplifiers.
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 ...
The Colpitts is distinguished in that feedback is taken from a capacitive voltage divider across the inductor. The Clapp oscillator has a capacitive voltage divider, but it is not across the inductor; there is an extra capacitor in there. Fig. 2 of the Colpitts patent clearly shows a capacitor voltage divider connected to the tube's cathode.
Transconductance (for transfer conductance), also infrequently called mutual conductance, is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device. Conductance is the reciprocal of resistance. Transadmittance (or transfer admittance) is the AC equivalent of transconductance.
A voltage-controlled crystal oscillator (VCXO) is used for fine adjustment of the operating frequency. The frequency of a voltage-controlled crystal oscillator can be varied a few tens of parts per million (ppm) over a control voltage range of typically 0 to 3 volts, because the high Q factor of the crystals allows frequency control over only a ...
Paul Voigt patented a negative feedback amplifier in January 1924, though his theory lacked detail. [4] Harold Stephen Black independently invented the negative-feedback amplifier while he was a passenger on the Lackawanna Ferry (from Hoboken Terminal to Manhattan) on his way to work at Bell Laboratories (located in Manhattan instead of New Jersey in 1927) on August 2, 1927 [5] (US Patent ...
The oscillator's stability is due largely to the dependency of the tube's (or transistor's) forward transconductance on the resonant frequency (ω) of the tuned circuit. Specifically, Vackář found that forward transconductance varied as ω 3 for the Clapp oscillator, as 1/ ω for the Seiler oscillator, and as ω / Q for his design, where the ...