100Khz sine oscillator


Posted on Feb 6, 2014

All you really need is a decent opamp, three resistors, three caps. Make one of the resistors adjustable, otherwise all components same value. It`s called a phase shifted oscillator and it has very good, very low distortion. The gain of the amplifier is set by two additional resistors. That`s one way. Another is a simple 555 square wave oscillator


100Khz sine oscillator
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, then use an R/C filter to, Trim,  the harmonics (edges, )which will have produce bit of distortion but you can control that by setting the R/C corner frequency, then make up for lost gain with a second stage of gain to get back your amplitude. The start though is a good accurate square wave, symmetrical, because the R/C filter will not, can not fix asymmetry. Is a web site that shows the principal of the phase shifter oscillator circuit and others as well. Each of the three phase shift stages attenuates the signal -6 dB so the amplifier needs 3G—6 or 18 dB of gain, which is a gain of 8, not hard to do and is more linear given lower gain. This circuit though is just an NPN transistor, simple but it is load sensitive so that could be a problem. Op amps would work better in this application if you need to drive some significant load.




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