Calibration of group delay in a mobile device

Abstract

The transmission and reception group delay in a front end structure of a mobile device may be determined using closed loop calibration. The closed loop may be a near field radiated closed loop between pairs of antennas in an antenna array of the mobile device. The delay based on time of transmission and time of reception may be measured for a plurality of pairs of antennas, from which the transmit and receive group delay within a single path may be determined. The propagation delay of the signal between antennas may be included in the group delay calibration for increased accuracy. In another implementation, a conducted closed loop, e.g., in the transceiver or in a radio frequency switching network may be used to calibrate the group delay. Pre-characterization of the delay caused by components between the closed loop and antennas may be included in the group delay calibration for increased accuracy.