Low Distortion Sine Wave Oscillator

An oldie but goodie.

Low distortion sine wave oscillator.

A do it yourself wien rc bridge sine generator with ultra low distortion in a range almost impossible to measure. An sine oscillator good for distortion measurment of operational amplifiers and audio equipment. Any impurity represents distortion and that means added harmonics that make very low distortion measurements impossible. Total harmonic distortion thd.

The output of the ltc1968 equals the rms level of the sine wave divided by 3. With a control voltage vg of 0 1 to 2v one can obtain over a decade of tuning range with oscillation frequencies from 200khz to 3mhz in this particular design. It can be used. I have changed the frequency setting capacitors c1 and c2 for 10nf otherwise the resistors r1 and r2 for 10khz are then far too low and the values for r1 and r2 become approx 39k 15 9k and 1 59k for the three frequencies.

Instead of driving the tuned circuit with a square wave a symmetrically clipped sine wave is used. The popular wien bridge oscillator. 8 bitdac requires a clock that is 256 output sine wave frequency and dac glitching and settling which will introduce significant distortion as output frequency increases. Low noise low distortion sine wave generator for testing adc demo boards demonstration circuit 1858a is a low noise low distortion sine wave generator designed to be used in conjunction withlineartechnology 16 bit and 18 bit adc demoboards.

A lower distortion oscillator is needed. The clipped sine wave of course has less distortion than a square wave and yields a low distortion output when filtered. I have built this low distortion oscillator modified to give three switcheable spot frequencies of 400hz 1khz and 10khz. Sine wave may be the input to a device or circuit with the output harmonics measured to determine the amount of distortion.

3 low distortion oscillation in many applications the distortion levels of a phase shift oscillator are unacceptable. A low distortion tuneable sine wave oscillator one can make a low distortion tuneable oscillator by incorporating an active filter inside an agc loop. Frequency can be varied by using pots for r and using different values of c switched in. A popular low frequency audio and up to about 100 khz or so sine wave oscillator is the wien bridge shown in figure 1.

If an amplifier under test has a distortion of 0 01 the oscillator has to be at least 10 times better 0 001 or the measurement taken is not a true reflection of the amplifier s thd total harmonic distortion plus noise. Ultra low distortion audio oscillator the neverending search for a pure sine ultra low harmonic distortion 10khz oscillator with 160dbc. 2 sine wave oscillator defined op amp oscillators are circuits that are unstable not the type that are. The waveforms in relaxation oscillators are generated from sine waves that are summed to provide a specified shape.