| 摘要 |
To be able to recover from modes in which the oscillation of the voltage-controlled oscillator (V0) stops, the phase/frequency control circuit includes an RS flip-flop (RS) connected via two AND gates (U3, U3) to the two outputs (A1, A2) of the phase discriminator (P), which provide pulses for raising and lowering, respectively, the frequency of the voltage-controlled oscillator (V0). When the frequency/phase control circuit is out of lock, a pulse is generated with two monostable multivibrators (M1, M2) which passes through a signal selection circuit (S1) associated with the Q output of the RS flip-flop or through a signal selection circuit (S2) associated with the &upbar& Q output of this flip-flop and controls the constant-current source (Q1) charging the smoothing device (G) or the constant-current source (Q2) discharging this device in such a way that the unwanted mode can be stopped by changing the control voltage of the oscillator (V0). |
