Systems and methods for controlling local oscillator feed-through

摘要

A method for controlling local oscillator (LO) feed-through in a direct transmitter includes detecting a signal level corresponding to LO feed-through in a radio frequency (RF) signal that is output by a direct transmitter. Responsive to detecting the signal level corresponding to LO feed-through, DC offset levels are modified for an in-phase (I) signal and/or a quadrature-phase (Q) signal in the direct transmitter.

主权项

1. A method comprising:
convolving signal components of a radio frequency (RF) signal generated by a transmitter to generate a detector signal, the detector signal having at least a side band tone and a local oscillator (LO) feed-through tone, the LO feed-through tone of the detector signal corresponding to a cross-product of a LO feed-through tone of the RF signal generated by the transmitter and a side band tone of the RF signal generated by the transmitter, the LO feed-through tone of the detector signal having a greater magnitude than a corresponding LO feed-through tone in the RF signal generated by the transmitter; digitizing a processed version of the detector signal to generate a digitized signal using an analog-to-digital converter, the analog-to-digital converter having a sampling rate that is greater than two times a noise bandwidth of a filter in a signal path associated with the detector signal; filtering the digitized signal to attenuate the side band tone and provide a filtered signal in which the LO feed-through tone has a greater magnitude than any other tone of the filtered signal; detecting a signal level corresponding to LO feed-through in the RF signal of the transmitter based at least in part on said filtering; and responsive to detecting the signal level, modifying at least one of a direct current (DC) offset level for an in-phase (I) signal in the transmitter and a DC offset level for a quadrature-phase (Q) signal in the transmitter.