Phase locked loop with rapid phase pull-in circuit

Claim 2

A phase synchronizing circuit having a loop with a pseudo stable point comprising a phase detector having inputs and an output, a loop filter and a voltage-controlled oscillator having an input and an output, input means connected to the phase detector for supplying to said phase detector a phase modulated wave input signal of n phases, wherein n is an integer corresponding to the number of phases of the input signal, coupling means connecting the output of the oscillator to an input of the phase detector, said phase detector comparing the phase of the output oscillation of the oscillator with the phase of the input signal, the output of the phase detector being coupled to the input of the oscillator so that the output voltage of the phase detector controls the frequency of oscillation of the oscillator in proportion to the phase difference between said oscillation and the input signal, said phase synchronizing circuit comprising an additional phase detector connected between the input means and the oscillator, phase shifting means connected between the oscillator and the additional phase detector for shifting the phase of the output of said oscillator, the additional phase detector comparing the phase of the input signal with the phase of the shifted output of the oscillator prior to the supply of the input signal to the phase detector, additional coupling means connecting the output of the addItional phase detector to the oscillator for shifting the phase of the oscillator by substantially pi /n radians when the phase of the input signal is near the pseudo stable point of the loop, and input control means connected to and controlling the input means for supplying the input signal to the loop after the shifting of the phase of the oscillator.

Claim 3

A phase synchronizing circuit having a loop with a pseudo stable point comprising a phase detector having inputs and an output, a loop filter and a voltage-controlled oscillator having an input and an output, input means connected to the phase detector for supplying to said phase detector a phase modulated wave input signal of n phases, wherein n is an integer corresponding to the number of phases of the input signal, coupling means connecting the output of the oscillator to an input of the phase detector, said phase detector comparing the phase of the output oscillation of the oscillator with the phase of the input signal, the output of the phase detector being coupled to the input of the oscillator so that the output voltage of the phase detector controls the frequency of oscillation of the oscillator in proportion to the phase difference between said oscillation and the input signal, said phase synchronizing circuit comprising an additional phase detector connected between the input means and the oscillator, phase shifting means connected between the oscillator and the additional phase detector for shifting the phase of the output of said oscillator, the additional phase detector comparing the phase of the input signal with the phase of the shifted output of the oscillator prior to the supply of the input signal to the phase detector, additional coupling means connecting the output of the addItional phase detector to the oscillator for shifting the phase of the oscillator by substantially pi /n radians when the phase of the input signal is near the pseudo stable point of the loop, and input control means connected to and controlling the input means for supplying the input signal to the loop after the shifting of the phase of the oscillator.

Claim 4

A phase synchronizing circuit having a loop with a pseudo stable point comprising a phase detector having inputs and an output, a loop filter and a voltage-controlled oscillator having an input and an output, input means connected to the phase detector for supplying to said phase detector a phase modulated wave input signal of n phases, wherein n is an integer corresponding to the number of phases of the input signal, coupling means connecting the output of the oscillator to an input of the phase detector, said phase detector comparing the phase of the output oscillation of the oscillator with the phase of the input signal, the output of the phase detector being coupled to the input of the oscillator so that the output voltage of the phase detector controls the frequency of oscillation of the oscillator in proportion to the phase difference between said oscillation and the input signal, said phase synchronizing circuit comprising an additional phase detector connected between the input means and the oscillator, phase shifting means connected between the oscillator and the additional phase detector for shifting the phase of the output of said oscillator, the additional phase detector comparing the phase of the input signal with the phase of the shifted output of the oscillator prior to the supply of the input signal to the phase detector, additional coupling means connecting the output of the addItional phase detector to the oscillator for shifting the phase of the oscillator by substantially pi /n radians when the phase of the input signal is near the pseudo stable point of the loop, and input control means connected to and controlling the input means for supplying the input signal to the loop after the shifting of the phase of the oscillator.

Claim 5

A phase synchronizing circuit as claimed in claim 1, wherein the phase shifting means comprises a phase shifter connected between the output of the oscillator and the additional phase detector.

Claim 6

A phase synchronizing circuit as claimed in claim 2, wherein the additional coupling means includes discriminator means having an input connected to the output of the additional phase detector and an output and pulse generator means connected between the output of the discriminator means and the input of the oscillator.

Claim 7

A phase synchronizing circuit as claimed in claim 3, wherein the input control means comprises pulse generator means connected to said input means and to said discriminator means.

Claim 8

A phase synchronizing circuit having a loop with a pseudo stable point comprising a phase detector having inputs and an output, a loop filter and a voltage-controlled oscillator having an input and an output, input means connected to the phase detector for supplying to said phase detector a phase modulated wave input signal of n phases, wherein n is an integer corresponding to the number of phases of the input signal, coupling means connecting the output of the oscillator to an input of the phase detector, said phase detector comparing the phase of the output oscillation of the oscillator with the phase of the input signal, the output of the phase detector being coupled to the input of the oscillator so that the output voltage of the phase detector controls the frequency of oscillation of the oscillator in proportion to the phase difference between said oscillation and the input signal, said phase synchronizing circuit comprising an additional phase detector connected to the input means, phase shifting means comprising a ring modulator connected to the output of the oscillator for shifting the phase of the output of said oscillator, the additional phase detector comparing the phase of the input signal with the phase of the shifted output of the oscillator prior to the supply of the input signal to the phase detector, said ring modulator having an output, additional coupling means connecting the output of the additional phase detector to the ring modulator for shifting the phase of the oscillator by substantially pi /n radians when the phase of the input signal is near the pseudo stable point of the loop, input control means connected to and controlling the input means for supplying the input signal to the loop after the shifting of the phase of the oscillator, and a phase shifter connected between the output of the ring modulator and the additional phase detector.

Claim 9

A phase synchronizing circuit having a loop with a pseudo stable point comprising a phase detector having inputs and an output, a loop filter and a voltage-controlled oscillator having an input and an output, input means connected to the phase detector for supplying to said phase detector a phase modulated wave input signal of n phases, wherein n is an integer corresponding to the number of phases of the input signal, coupling means connecting the output of the oscillator to an input of the phase detector, said phase detector comparing the phase of the output oscillation of the oscillator with the phase of the input signal, the output of the phase detector being coupled to the input of the oscillator so that the output voltage of the phase detector controls the frequency of oscillation of the oscillator in proportion to the phase difference between said oscillation and the input signal, said phase synchronizing circuit comprising an additional phase detector connected to the input means, phase shifting means comprising a ring modulator connected to the output of the oscillator for shifting the phase of the output of said oscillator, the additional phase detector comparing the phase of the input signal with the phase of the shifted output of the oscillator prior to the supply of the input signal to the phase detector, said ring modulator having an output, additional coupling means connecting the output of the additional phase detector to the ring modulator for shifting the phase of the oscillator by substantially pi /n radians when the phase of the input signal is near the pseudo stable point of the loop, input control means connected to and controlling the input means for supplying the input signal to the loop after the shifting of the phase of the oscillator, and a phase shifter connected between the output of the ring modulator and the additional phase detector.

Claim 10

A phase synchronizing circuit as claimed on claim 5, wherein the additional coupling means comprises discriminator means having an input connected to the output of the additional phase detector and an output, flip flop means having an input and an output, gate means coupling the output of the discriminator means to the input of the flip flop means and drive amplifier means connected between the output of the flip flop means and the ring modulator.