PHASE ERROR DETECTION CIRCUIT

摘要

PURPOSE:To attain a fast phase locking by deciding a detected phase at plural regions and changing the phase of a reference timing signal based on the result so as to eliminate the increase in the detection error caused at the phase error of nearly + or -pi. CONSTITUTION:The 1st recovery timing signal 2 is retarded by 1/2 of the transmission rate at the 2nd delay circuit 17 to generate a comparison signal 18, which is compared with the 1st transmission rate frequency component 5 at the 2nd latch circuit 16 to apply phase decision. The phase decision signal 13 switches the phase of the 1st recovery timing signal 2 in an EX-OR circuit 15 to generate the 2nd recovery timing signal 14. A demodulated base band signal 1 is inputted to the 1st latch circuit 9 and the 2nd recovery timing signal 14 extracts the 2nd transmission rate frequency component 6 including the phase error information and the recovered base band signal 4. A substraction circuit 12 subtracts the 2nd transmission rate frequency component 6 from the 1st transmission rate frequency component 5 to extract a phase error signal 7.