A gain and phase control system performs a gain (or phase) adjustment based on the results of a previous gain (or phase) adjustment after an intervening phase (or gain) adjustment. A gain adjustment is based on the results of a previous gain adjustment rather than on the results of an intervening phase adjustment. A phase adjustment is based on the results of a previous phase adjustment rather than the results of an intervening gain adjustment. As such, the above-mentioned increase in error signal does not occur because a gain adjustment is based on the results of the previous gain adjustment, and a phase adjustment is based on the results of the previous phase adjustments. In accordance with another aspect of the present invention, the gain and phase control system makes a gain (or phase) adjustment in parallel with detecting the results from a previous phase (or gain) adjustment, thereby taking advantage of the delay between adjustment and detection of the resulting error signal to improve the convergence rate. For example, the gain and phase control system can perform single alternating gain and phase adjustments and make a gain (or phase) adjustment while detecting the error signal resulting from a preceding phase (or gain) adjustment. When the error signal resulting from the gain (or phase) adjustment is being detected, the gain and phase control system makes a phase (or gain) adjustment using the results detected from the preceding phase (or gain) adjustment.