Independent LO IQ tuning for improved image rejection

Details Independent LO IQ tuning for improved image rejection Independent LO IQ tuning for improved image rejection

2005-06-29

2010-12-07

Liu, Shuwang (Department: 2611)

Pulse or digital communications

Transmitters

Quadrature amplitude modulation

C375S295000, C375S219000, C375S226000, C375S227000, C375S229000, C455S109000, C455S047000, C455S302000, C327S234000

Reexamination Certificate

active

07848453

ABSTRACT:
A transmitter includes a first amplifier to amplify an in-phase oscillator signal to produce an in-phase mixing signal and a second amplifier to amplify a quadrature-phase oscillator signal to produce a quadrature-phase mixing signal. A first mixer mixes the in-phase mixing signal with a first information signal to produce a first output signal. A second mixer mixes the quadrature-phase mixing signal with a second information signal to produce a second output signal. The first output signal and an inverted second output signal are summed to produce a transmitter output signal that includes an image signal caused by a phase imbalance between the in-phase and quadrature-phase mixing signals. An image monitor monitors the image signal and reduces or eliminates the phase imbalance by independently adjusting a phase of the in-phase mixing signal and/or a phase of the quadrature-phase mixing signal. Consequently, a power of the image signal is reduced or eliminated.

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