| 摘要 |
PURPOSE:To prevent carrier leakage, unbalanced amplitude of I and Q signals and to calibrate a quadrature phase error by adjusting amplitude and phase differences of carrier signals generated from carrier signal generators so as to decrease the frequency component being a difference of frequencies from the two signal generators. CONSTITUTION:A time (t) from a time base 1 is inputted to carrier signal generators 2 to 4. The generators 2 to 4 respectively generate carrier signals cos(2pifct), Acos(2pifct+90 deg.+DELTAphi) (amplitude A and phase DELTAphi are variable) and Bcos(2pifct+DELTApsi) (amplitude B and phase DELTApsi are variable). Output signals from the generators 2, 3 and signals I(t), Q(t) are respectively multiplied by multipliers 5, 6, and the signals and the signal from the generator 4 are added by an adder circuit 7. At first the I and Q signals are respectively set to cos(2pifst) and sin(2pifst). Then the amplitude B is set to 0 and the amplitude A and the phase difference DELTAphi of the output of the generator 3 are adjusted so that a scalar detector 8 detects a smaller frequency component of fc-fs with respect to a frequency component fc+fs. Furthermore, the amplitude B is adjusted to decrease the frequency component fc. |
