Phase Locked Loop Oscillator

PLLVCO is a module that combines a Phase Locked Loop (PLL) circuit with an analog oscillator.

The oscillator’s pitch can be controlled to a rational multiple (N/M) of the frequency of the external oscillator input to the PLL. Additionally, pitch control using a standard V/Oct voltage is also possible.

For example, by controlling the frequency of an internal oscillator to 3/2 times (x 1.5) the frequency of an externally input oscillator, and then mixing these two oscillators with an external mixer, it is possible to create an oscillator that produces chords overlapping by a perfect fifth.

Furthermore, when an external audio signal is input to the PLL input, the pitch of the input audio is detected and output as a V/Oct voltage from the FRQ output. It offers interesting applications, such as inputting vocals or guitar sounds as external audio and controlling the pitch of another, more complex oscillator via the FRQ output. (However, it may not be able to detect input audio that is a chord or has complex harmonics.)

The pitch tracking speed using the PLL circuit can be adjusted with the SENS slider. Furthermore, if tracking is too fast, phase distortion will occur in the waveform, resulting in a tonal change similar to oscillator sync. Therefore, you should normally set the SENS speed to a level where phase distortion does not occur.

The frequency range can be set to either a VCO or an LFO, and when set to LFO, it can also be used as a clock-synchronized LFO. In this case, as with the VCO, it can oscillate at a speed that is a rational number of times the input clock, so it can be used as a clock divider or multiplier.

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