Circuit arrangement for enhancing the frequency precision of a reference oscillator used in radio engineering

摘要

A circuit arrangement for enhancing the frequency precision and reducing the circuit expenditure of a reference oscillator used in radio engineering, particularly for mobile radio telephones, is proposed in which the demodulated data frequency coming from the base station is used as reference frequency. The reference oscillator is corrected via a control circuit, the control voltage being obtained by taking into consideration the frequency of the reference oscillator and the data frequency. The reference frequency of the reference oscillator is selected in such a manner that it is an integral multiple of the data frequency. The frequency of the reference oscillator, after being divided, is compared with the data frequency. The signal resulting from the comparison is supplied to a D/A converter, the output voltage of which is supplied as control voltage to the control input of the reference oscillator. IMAGE