Method and apparatus for compensating for imbalances between quadrature signals

A method for balancing a complex signal transceiver, comprising:

• receiving a first complex signal;
• separating the first complex signal into first inphase and quadrature components;
• processing the first inphase and quadrature components and determining an imbalance between the first inphase and quadrature components;
• generating a correction factor based on the determined imbalance:
• receiving a second complex signal:
• separating the second complex signal into second inphase and quadrature components:
• and
• balancing the second inphase and quadrature components using the correction factor,
• wherein amplitude and phase corrections are determined for multiple gain levels.

A method for balancing a complex signal transceiver, comprising:

• receiving a first complex signal:
• separating the first complex signal into first inphase and quadrature components;
• processing the first inphase and quadrature components and determining an imbalance between the first inphase and quadrature components;
• generating a correction factor based on the determined imbalance;
• receiving a second complex signal;
• separating the second complex signal into second inphase and quadrature components;
• and
• balancing the second inphase and quadrature components using the correction factor,
• wherein the first complex signal is a modulated signal having known modulation characteristics, the method further comprising:
• comparing the known modulation characteristics to modulation characteristics of the received second complex signal to determine the imbalance.

A method for balancing a complex signal transceiver, comprising:

• receiving a first complex signal;
• separating the first complex signal into first inphase and quadrature components;
• processing the first inphase and quadrature components and determining an imbalance between the first inphase and quadrature components;
• generating a correction factor based on the determined imbalance;
• receiving a second complex signal;
• separating the second complex signal into second inphase and quadrature components;
• and
• balancing the second inphase and quadrature components using the correction factor,
• wherein the generating step further comprises:
• detecting a current temperature;
• taking into account an effect of the detected temperature on the imbalance in the correction factor.

A method of balancing a receiver that receives a quadrature signal having inphase and quadrature components, comprising:

• determining an imbalance between the inphase and quadrature components;
• generating a correction factor to compensate for the determined imbalance including:
• generating a phase control signal for controlling a phase angle between inphase and quadrature components of the subsequently received signal, and
• generating an amplitude adjustment factor to be applied to the amplitude of the inphase and quadrature components of the subsequently received signal;
• applying the correction factor to a subsequently received signal to reduce an imbalance between inphase and quadrature components of the subsequently received signal;
• and
• iteratively varying the phase control signal and the amplitude adjustment factor until a minimum imbalance signal is obtained.

A radio receiver, comprising:

• an antenna;
• a signal generator for generating a known radio frequency (RF) signal;
• a quadrature demodulator for receiving RF signals including the known RF signal and converting the received RF signals including the known RF signal into inphase baseband and quadrature baseband signals including:
• a frequency generator tuned to a radio receive channel at a first frequency;
• a first mixer connected to the frequency generator output and converting the received RF signal into an inphase baseband signal;
• a phase splitter for generating an RF output signal at the first frequency and out of phase with the frequency generator applied by 90 degrees including a tunable filter for adjusting the phase shift applied to the RF oscillator output;
• and
• a second mixer connected to the phase splitter for converting the received RF signal into a quadrature baseband signal, and
• a signal processor determining an imbalance between the inphase and quadrature signals of the known RF signal, generating a correction factor, and applying the correction factor to subsequently received inphase and quadrature baseband signals to minimize an imbalance between the subsequently received inphase and quadrature baseband signals;
• and
• a switch for connecting one of an antenna and the signal generator to the quadrature demodulator, wherein the signal processor controls the switch to connect the signal generator to the quadrature receiver to initialize the radio receiver at power up or to update the radio receiver during the idle time periods and controls the switch to connect the antenna to the quadrature receiver at times other than power up or the idle times.

A radio receiver, comprising:

• an antenna;
• a signal generator for generating a known radio frequency (RF) signal;
• a quadrature demodulator for receiving RF signals including the known RF signal and converting the received RF signals including the known RF signal into inphase baseband and quadrature baseband signals;
• and
• a signal processor determining an imbalance between the inphase and quadrature signals of the known RF signal, generating a correction factor, and applying the correction factor to subsequently received inphase and quadrature baseband signals to minimize an imbalance between the subsequently received inphase and quadrature baseband signals;
• and
• an automatic gain controller, wherein the signal processor determines the correction factor for multiple gain levels.

A radio receivers comprising:

• an antenna:
• a signal generator for generating a known radio frequency (RF) signal;
• a quadrature demodulator for receiving RF signals including the known RF signal and converting the received RF signals including the known RF signal into inphase baseband and quadrature baseband signals;
• and
• a signal processor determining an imbalance between the inphase and quadrature signals of the known RF signal, generating a correction factors and applying the correction factor to subsequently received inphase and quadrature baseband signals to minimize an imbalance between the subsequently received inphase and quadrature baseband signals,
• wherein the signal processor determines the correction factor for different temperatures.

A radio receiver, comprising:

• an antenna;
• a signal generator for generating a known radio frequency (RF) signal;
• a quadrature demodulator for receiving RF signals including the known RF signal and converting the received RF signals including the known RF signal into inphase baseband and quadrature baseband signals;
• and
• a signal processor determining an imbalance between the inphase and quadrature signals of the known RF signal, generating a correction factors and applying the correction factor to subsequently received inphase and quadrature baseband signals to minimize an imbalance between the subsequently received inphase and quadrature baseband signals,
• wherein the signal generator includes a frequency generator connected to an attenuator, generating a first signal having a frequency that is different from a receive frequency to which the radio receiver is currently tuned, and
• wherein the signal processor controls the frequency generator and the receive frequency to maintain the frequency difference.

A radio transceiver, comprising:

• an antenna;
• a signal generator generating a known radio frequency (RF) signal;
• a quadrature demodulator demodulating the known RF signal and converting the received RF signal into an inphase baseband signal and a quadrature baseband signal;
• a signal processor determining a quadrature demodulator imbalance between the inphase and quadrature signal, generating a correction factor, and applying the correction factor to subsequently received inphase and quadrature signals to compensate for the quadrature demodulator imbalance;
• and
• a quadrature modulator connected to the signal processor and the antenna, wherein the compensated inphase and quadrature signals are modulated by the quadrature modulator.

A radio receiver, comprising:

• an antenna;
• a signal generator for generating a test signal at a known radio frequency (RF) signal;
• a quadrature receiver for receiving RF signals including the test signal and converting received RF signals into inphase baseband and a quadrature baseband signals;
• and
• a digital signal processor for performing the following tasks:
• determining an imbalance in the quadrature receiver between the inphase and quadrature signals of the test signal under varying conditions,
• generating a correction factor for at least some of the varying conditions, and
• applying one or more correction factors to subsequently received inphase and quadrature baseband signals depending on a current condition to minimize an imbalance between the subsequently received inphase and quadrature baseband signals.