PURPOSE: To simplify circuit constitution by finding out the product of outputs from two correlators without requiring balance between the correlators and extracting an inverse spread signals.

CONSTITUTION: A local oscillation signal is inputted to a Gilbert cell 2. A PN signal is generated from a PN signal generator 8 and inputted to the cell 2. A signal indicating the product of the PN signal and the local oscillation signal is obtained respectively as a positive phase signal and a reverse phase signal. An output signal from a Gilbert cell 3 is inputted to a band pass filter (BPF) 5a to find out correlation. An output from a Gilbert cell 4 is also inputted to a BPF 5b to find out correlation and these correlation signals are inputted to a Gilbert cell 7. An output from the cell 7 is passed through a low pass filter (LPF) 10 and a control signal is obtained and inputted to a voltage control clock 9 to constitute a synchronizing loop.