Active-filter tuned oscillator: Difference between revisions
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*http://www.site.uottawa.ca/~rhabash/ELG4139LN3Oscillators.pdf |
*http://www.site.uottawa.ca/~rhabash/ELG4139LN3Oscillators.pdf |
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*http://www.tek.com/signal-generator |
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[[Category:Oscillators]] |
[[Category:Oscillators]] |
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Revision as of 09:09, 27 January 2014
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In most of the electronic companies and laboratories it is easy to find a signal generator which produces wave functions such as sinusoidals, square, pulse or triangular. Even in a simple microcontroller ic, pulse generation is required for the internal circuits.
Property of an Oscillator
The most interesting and basic property of an Oscillator is that it has finite output for zero input signal. This kind of circuit in electronics is named Oscillator. To have a simple sinusoidal wave, oscillation criterion should be satisfied at one frequency and that is the magnitude of the loop. Gain will be unity. If we consider differential equations, the roots of the characteristics equations for producing oscillatory output have to be: (S = +/-jw0). We work hard to make the loop (gain and amplitude multiplied) which together will be 1 for the desired frequency of oscillation.
Control of the Oscillated Signal Amplitude
Because we always try to control the amplitude and loop gain not to exceed than unit, a limiter circuit is a good solution. One of the popular one is using diodes and resistors. When the input voltage is positive the output will be negative and so forth.
The Active Filter Tuned Oscillator
A low distortion and simple oscillator output waves. A Bandpass filter is connected to positive Feedback loop, with hard Limiter. The square wave which is produced, will be fed into the filter, then to the output. If the filter will be sine wave with the same center frequency. The job of the filter is to give a signal without harmonics. Of course band pass filter should be stable.