US 10,333,764 B1 · Envelope detector-based feedback for radio frequency (RF) transmitters

Abstract

A transmitter is provided to address transmitter non-idealities. The transmitter uses a series of envelope detectors to detect imbalances between an I branch and a Q branch of an I/Q modulator that is implemented as part of the transmitter's front end, and these detected imbalances may be compensated by pre-distorting digital baseband signals fed to the I branch and the Q branch. The transmitter may also use a series of envelope detectors to detect nonlinearities in one or more of the transmitter's amplification stages, and these detected nonlinearities may be compensated by modifying the baseband signals via a digital linearization pre-compensator. The transmitter may also support both implementations in either a time-switched or simultaneous manner, allowing for I/Q imbalances and nonlinearities to be addressed using a single transmitter design.

Claims22

Dependent claims

A transmitter for compensating for in-phase/quadrature-phase (I/Q) imbalance, comprising:

an I branch and a Q branch configured to provide an in-phase signal component and a quadrature signal component, respectively;
an I/Q combiner configured to combine the in-phase signal component and the quadrature signal component to provide an I/Q signal;
a first, second, and third envelope detector configured to generate an I-branch envelope feedback signal, a Q-branch envelope feedback signal, and an I/Q envelope feedback signal based upon the in-phase signal component, the quadrature signal component, and the I/Q signal, respectively;
and
a pre-compensator configured to compensate for I/Q imbalance between the I branch and the Q branch using the I-branch envelope feedback signal, the Q-branch envelope feedback signal, and the I/Q envelope feedback signal.

2 more elements

A transmitter, comprising:

an in-phase (I) branch and a quadrature-phase (Q) branch configured to provide an in-phase signal component and a quadrature signal component, respectively, wherein an output signal transmitted by the transmitter is based upon a combination of the in-phase signal component and the quadrature signal component;
one or more amplifier stages configured to generate a transmitter output signal from the combination of the in-phase signal component and the quadrature signal component, the one or more amplifier stages having one or more nonlinear memory distortions;
a first envelope detector configured to generate an I-branch envelope feedback signal based upon a difference between the in-phase signal component and a probed transmitter output signal;
a second envelope detector configured to generate a Q-branch envelope feedback signal based upon a difference between the quadrature signal component and the probed transmitter output signal;
a third envelope detector configured to generate a transmitter output envelope feedback signal based upon the probed transmitter output signal;
and
one or more processors configured to generate an estimated complex lowpass equivalent (CLE) representation of the transmitted output signal based upon the I-branch envelope feedback signal, the Q-branch envelope feedback signal, and the transmitter output envelope feedback signal, and to utilize the CLE representation of the transmitted output signal as a reference signal to perform one or more of online identification, online calibration, and online self-interference cancellation.

4 more elements

A transmitter, comprising:

an in-phase (I) branch and a quadrature-phase (Q) branch configured to provide an in-phase signal component and a quadrature signal component, respectively, the I branch and the Q branch having one or more I/Q imbalances;
a first I/Q combiner configured to combine the quadrature signal component and the in-phase signal component to provide a first I/Q signal;
a second I/Q combiner configured to combine the quadrature signal component and the in-phase signal component to provide a second I/Q signal;
one or more amplifier stages configured to generate a transmitted output signal based upon the first I/Q signal, the one or more amplifier stages having one or more nonlinear memory distortions;
a first set of envelope detectors configured to generate one or more first envelope feedback signals based upon the first and the second I/Q signal;
a second set of envelope detectors configured to generate one or more second envelope feedback signals based upon a probed transmitted output signal;
and
one or more processors configured to calculate an estimated complex lowpass equivalent (CLE) representation of the transmitted output signal based upon at least one of (i) the one or more first envelope feedback signals, and (ii) the one or more second envelope feedback signals,
wherein the one or more processors are configured to utilize the CLE representation of the transmitted output signal as a reference signal to perform one or more of online identification, online calibration, and online self-interference cancellation.

6 more elements

Dependencies are inferred from the claim text.

Envelope detector-based feedback for radio frequency (RF) transmitters

Life of this patent

Envelope detector-based feedback for radio frequency (RF) transmitters

Life of this patent

Abstract

Claims22