Abstract: An electronic device may have a display such as a liquid crystal display. The display may have a color filter layer and a thin-film transistor (TFT) layer. An active portion of the display may contain an array of display pixels that are controlled by control signals that are provided over intersecting gate lines and data lines. In an inactive portion of the display, display driver circuitry may be used to provide data signals for the data lines. Each display pixel may be coupled to a corresponding gate line, data line, and may share a common electrode. Changes in the data signals may be coupled onto the common electrode to cause voltage rippling. Compensation circuitry may be coupled to the common electrode via an AC or a DC coupling connection to help reduce the voltage rippling.

Abstract: A carrier cancellation combiner, and pre-distortion and feed-forward loops of an RF power amplifier are controlled to minimize IMD components at the output of the RF amplifier, by a spectral distortion measurement scheme that performs Fast Fourier Transform (FFT)-based spectral power measurements at a ‘reference’ signal port (associated with the RF input signal), and a plurality of ‘test’ signal ports (associated with various monitoring locations of the amplifier). Signals extracted from the control and test ports are downconverted to baseband, bandpass filtered, digitized and stored as a spectral ‘snapshot’ of the entire band of the signal infrastructure of the amplifier. A digital signal processor-based controller processes the buffered data to produce averaged FFT's of the data extracted from the reference and test ports and thereby provide spectral information for each sampled signal set.