| 摘要 |
1,248,147. Phase locked loops.. SIGNETICS CORP. 28 Aug., 1969 [6-.Sept., 1968], No. 42881/69. Heading H3A. In a phase locked loop control system, the voltage controlled oscillator is a multivibrator comprising transistors Q5, Q6 which have the voltage swing at their collectors maintained at the forward junction voltage of diodes connected in the collector circuits, and the oscillation frequency is varied by controlled current sources Q10, Ql 1 connected in the emitter circuits of the transistors Q5, Q6 to give a linear voltage/ frequency characteristic. As described, the collector circuit diodes are the base-emitter junctions of transistors Ql ... Q4 which constitute the phase comparator of the loop. Incoming signals at V 1 are compared with the oscillator signal to produce an error signal V 2 which is fed via filter R1, R2, C 2 , C 3 to the bases of transistors Q9, Q10, Q11 which, together with-.constant current source I B , constitute the controlled current source feeding the multivibrator. The constant current source may be constituted by a transistor circuit as in the more detailed circuit diagram, Fig. 4 (not shown). The circuit is used as a demodulator for F.M. signals, the demodulated output V 3 being taken from the bases of Q9, Q10. |
