procedures for the enlargement of the durchlassfrequenzbandbreite a spannungsgesteuerten kristalloszillators and mitverbundene circuit

摘要

Process for broadening the frequency response band of a voltage-controlled crystal oscillator (VXCO) to be inserted in a phase-locked loop (PLL) used for recovery of the clock signal from a string of data transiting on optical fibre. The process consists primarily of low-pass filtering of the control signal of the VCXO and using the filtered signal to control the VCXO and a phase modulator to which arrives the signal generated by the VCXO. The cut-off frequency of the filter and the gains of the VCXO and modulator have values such that the output signal from the modulator consists mainly of the signal generated by the VCXO, as long as the frequency response thereof holds constant, or of the signal generated by the phase modulated VCXO, otherwise. The circuit which achieves the above process is also described. IMAGE