Phase difference and amplitude correction circuit

A circuit for generating two sinusoidal signals in quadrature and having equal amplitudes, said correction circuit, comprising a first quadrature phase comparator connected to receive as input two signals and to supply as output a first error signal the voltage of which is representative of the difference between the phase difference between the two signals and 90.degree., phase adjustment means responsive to said first error signal for correcting the phase of at least one of said two signals to maintain a phase difference of 90.degree. between them, analogue arithmetic processing means for supplying two linear combinations of said two signals, a second quadrature phase comparator connected to receive as input said two linear combinations and to supply as output a second error signal representative of the difference between the phase difference between said linear combinations and 90.degree., the respective coefficients of said linear combinations being chosen so that, when said two signals are in quadrature and have equal amplitudes, said second error signal indicates zero error, and amplitude adjustment means responsive to said second error signal, for correcting the amplitude of at least one of said two signals for maintaining said two signals at identical amplitudes.