Phase-locked loop using integrated switched filter

Details Phase-locked loop using integrated switched filter Phase-locked loop using integrated switched filter

1982-08-11

1985-06-18

LaRoche, Eugene R.

Oscillators

Automatic frequency stabilization using a phase or frequency...

Particular error voltage control

331 8, 331 25, 328155, H03L 708

Patent

active

045243336

ABSTRACT:
A phase-locked loop circuit provides a phase comparator which receives input signals through a first input terminal, a loop filter which receives a first output and a second output of the phase comparator, and a voltage-controlled oscillator which produces output signals of an oscillation frequency proportional to the first output and the second output of the loop filter. The signals corresponding to the output signals produced by the voltage-controlled oscillator are supplied to a second input terminal of the phase comparator so that the phase of the signals supplied to the first input terminal of the phase comparator is compared with the phase of the signals supplied to the second input terminal. In the present invention, the loop filter comprises a first capacitor connected to the output terminal of the loop filter, second and third capacitors, each having a terminal connected to the output terminal of the loop filter, and a charging circuit for electrically charging the first, second, and third capacitors. The charging circuit is connected in parallel with the second capacitor. A discharging circuit for discharging the first, second, and third capacitors is connected in parallel with the third capacitor.

REFERENCES:
patent: 4163951 (1979-08-01), Aihara et al.
patent: 4208635 (1980-06-01), Fazakerly et al.
patent: 4371975 (1983-02-01), Dugan
IEEE Journal of Solid-State Circuits, vol. SC-16, No. 4, Aug. 1981, pp. 315-321, New York, A. Iwata et al.; "A Single-Chip Codec with Switched-Capacitor Filters", p. 318, right-hand column, line 18, p. 319, left-hand column, line 24; Figs. 7, 8.
IEEE Transactions on Acoustics, Speed & Signal Processing, vol. ASSP-29, No. 3, part III, Jun. 1981, pp. 736-744, New York, K. Martin et al., "Switched-Capacitor Building Blocks for Adaptive Systems", p. 736, right-hand column, line 23-p. 738, left-hand column, line 16, Figs. 1, 3.
European Search Report, Examiner I. E. E. Dhondt, 17-05-83, The Hague.

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