Abstract: A mixed-signal circuit may include an analog circuit and a digital circuit coupled to the analog circuit, wherein the analog circuit is configured to, in a normal operation mode, provide an analog signal to the digital circuit, and wherein the digital circuit is configured to, in the normal operation mode, provide a digital signal to the analog circuit, the mixed-signal circuit may further include a test signal generator configured to, during a test operation mode, receive the digital signal from the digital circuit, generate a test signal based on the digital signal, and provide the test signal to the digital circuit, wherein the test signal generator is configured to generate the test signal using an emulation of the analog circuit, and wherein the mixed-signal circuit is tested based on an output of the digital circuit that is generated in response to the test signal.

Abstract: Digital predistortion (DPD) timing alignment in a remote unit(s) for a wireless communications system (WCS) is disclosed. In examples discussed herein, a remote unit includes a power amplifier (PA) configured to amplify a radio frequency (RF) signal before transmission. The RF signal may include an unwanted distortion term and a DPD circuit is provided in the remote unit to create an artificial distortion term to help cancel out the unwanted distortion term. The remote unit includes a DPD front-end circuit configured to generate a digital training signal corresponding to a predefined waveform pattern. The DPD circuit can be configured to perform a DPD timing alignment based on the predefined waveform pattern to determine a timing offset that is need to create the artificial distortion term. As such, it may be possible to effectively cancel the unwanted distortion term in the RF signal to improve efficiency and linearity of the PA.