Low-frequency, low-distortion digital quadrature oscillator
A. F. Borghesani · Journal of Physics E Scientific Instruments · 1989
Digital recursive and non-recursive filtering techniques have both been exploited to build a low-frequency (0.5-50 Hz), low-distortion digital quadrature oscillator. This generator shows an amplitude constant to within 0.3% over the frequency range, and the quadrature phase error is within +or-0.05 degrees .