Phase and gain error control system for use in an I/Q direct conversion receiver

A process for controlling gain and phase errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q baseband component signals which are in quadrature, comprising the steps of:

• (1) generating an error signal .theta..sub.E by differencing a first phase angle signal .theta..sub.B based on said I and Q signals with a second phase angle signal .theta..sub.A based on I' and Q' signals approximately representing 2IQ and I.sup.2 -Q.sup.2 as adjusted to substantially remove their DC components in order to reduce gain and phase errors;
• (2) analyzing said error signal .theta..sub.E as a function of phase angle in order to determine the phase error p and gain error g between the signal channels in the receiver;
• and
• (3) adjusting said I and Q signals in order to correct for gain and phase errors between said signal channels in accordance with said gain and phase error signals g and p.

An apparatus for controlling errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q baseband signals which are in quadrature, said apparatus comprising:

• (1) means for generating I' and Q' signals which correspond to analogs of said I and Q signals but are characterized by reduced gain and phase errors;
• (2) means for forming a first phase angle signal .theta..sub.A based on said I' and Q' signals;
• (3) means for forming a second phase angle signal .theta..sub.B based on said I and Q signals;
• (4) means for forming a phase angle error signal .theta..sub.E based on said first and second phase angle signals .theta..sub.A and .theta..sub.B ;
• (5) means for analyzing said phase angle error signal .theta..sub.E to determine phase error p;
• and
• (6) means for adjusting the relationship between said I and Q signals to correct for said phase error p.

A process for correcting errors between signal channels in a direct conversion receiver having a pair of signal channels carrying I and Q baseband signals which are in quadrature, said process comprising the steps of:

• (1) generating I' and Q' signals which may be viewed as analogs of said I and Q signals but which are characterized by reduced gain and phase errors;
• (2) forming a phase angle error signal .theta..sub.E from said I and Q baseband signals and said I' and Q' signals;
• (3) analyzing said phase angle error signal .theta..sub.E to determine phase error p;
• and
• (4) adjusting the relationship between said I and Q signals to correct for said phase error p.