Calibrating signal path interconnect delay in remote radio head base stations and other applications.

Calibrating delays through a signal path is growing in importance as systems become faster and more parallel. Often, the system needs to know the delay from the central processing unit to remote a/d and d/a modules and then be able to compensate for any delay variations between one signal path and the others. Delay calibration may be useful in such applications as wireless base stations, test equipment, medical imaging and other high performance designs.
There is a growing trend in wireless base station design to move the radio electronics from the base station to the antennas, increasing radio efficiency, flexibility and coverage, whilst consolidating dsp and backhaul resources. However, synchronising remote radio heads (RRHs) back to the central base station ‘hotel’ can be a challenge. A further challenge is to calibrate every delay path from each antenna to the base station.