The circuit of Figure 1 generates sinusoids down to very low frequencies with distortion in the region of 3% or less, yet has no feedback or gain-stabilizing components because none are needed. It ...

Fig 1. Two analog multipliers form a VCO with quadrature outputs, while a third multiplier provides AGC to stabilize output voltages without adding distortion. Fig 2. The oscilloscope trace of the VCO ...