| 摘要 |
PURPOSE:To quicken the response speed of a carrier regenerating loop circuit by constituting a 4-signal multiplication circuit with three sets of dual differential amplifiers of tandem connection so that a multiplication output of the pre-stage is a signal input directly to a multiplication circuit of the next stage. CONSTITUTION:An output of a low-pass filter 24 of a 4-signal multiplication circuit M controls a voltage controlled oscillator 25 and a carrier regnerating circuit of Costas loop feeding back each reference phase carrier of in phase and orthogonal phase to phase detectors 20, 21 is provided. Multiplication output currents IC1, IC2 of demodulation signals P, Q of the pre-stage are respective common emitter currents of dual differential amplifier circuits constituting the 2nd stage multiplication circuit and collector currents IC3, IC4 are respective common emitter currents of dual differential amplifier circuits constituting the 3rd stage multiplier circuit in the 4-signal multiplication circuit 1. Thus, the voltage as the result of multiplication from the 1st stage to the 3rd stage is outputted to load resistors R1, R2 from output terminals a, b. |
