DLL for maintaining synchronization between a received spreading code and a combined code generated by weighting and phase shifting a local spreading code

摘要

A delay locked loop circuit for maintaining phase synchronization between a received spreading code included in a spread-spectrum signal and a reference spreading code in a mobile communications system. A reference spreading code generator 51 generates the reference spreading code, and a combined code generator 52 generates a combined spreading code from the reference spreading code by applying weights to a plurality of phase shifted occurrences of the reference spreading code and then combining the weighted occurrences. An arithmetic circuit 53, 54 detects a phase difference between the received spread code B and the reference spreading code using the combined spreading code A, and a voltage controlled oscillator 55 controls a phase of the reference spreading code on the basis of the phase difference. The combined code generator makes positive, and successively reduces in magnitude, the weights of a number n of reference spreading codes of small phase shift constituting a first half of a number 2n (where n is a positive integer) of reference spreading codes that have been successively shifted in phase, and makes negative, and successively increases in magnitude, the weights of n constituting a second half of the reference spreading codes that have been successively shifted in phase.