SU437191A1 - Device for phase locked loop with automatic gain control - Google Patents

Description

one

The invention can be used for phase autotuning of generators with multiple frequencies, when the variation of the multiplicity changes the control voltage at the output of the phase detector, as a result of which the gain control is necessary.

A device for phase-locked loop with automatic gain control is known, comprising a tunable oscillator connected to a ring, a phase detector, a filter, an error signal amplifier and a control element, as well as an automatic gain control phase detector connected through a phase shifter to a reference oscillator and directly to adjustable generator.

The aim of the invention is to simplify the device while maintaining stability.

The goal is achieved in that the output of the automatic gain control amplifier is connected to the control input of the error signal amplifier.

The drawing shows a block diagram of the proposed device.

A phase locked loop (FATCH) with automatic gain control contains two identical phase detectors 1 and 2, one of which, for example detector 1, is connected by its inputs to reference 3 and adjustable by 4 oscillators directly, and the other, for example detector 2, by one of the inputs connected to one of the generators, for example with the reference generator 3, through the phase shifter 5, which gives the reduced phase shift / 2 + / C (/ (0,1,2,3 ...). The output of the phase detector 1 is connected through filter 6 to the inputs of the amplifier 7 signal error. The output of the last connected to the control member 8 directly through the integrating and

element 9. The control element 8 is connected by its output to a tunable generator 4. The output of the phase detector 2 through the filter 10 and the amplifier 11 of the automatic gain control is connected to the amplifier 7

signal fault.

Since the capture bandwidth in the PLL system is usually much smaller than the hold band (), despite the almost unchanged initial detuning between

generators at the first moment of action of an astatic PLL (integrating element) ring at the output of phase detector 2, a fairly significant signal containing a constant component, so

as the reduced phase difference of the oscillations, the input of the phase detector will lie within. This constant component also depends on the magnitudes of the signals at the input of the phase detector 2, as well as on the ratio between the frequencies. This AGC signal, amplified in amplifier 11, affects the error signal amplifier 7, changing its gain without changing the band of the laser (for example, the influence of the lamp segment) back 5 according to the magnitude of the maximum possible signal removed from the phase detector 2 (and, therefore, inversely proportional to the magnitude of the maximum possible signal taken from phase detector 1). 10 As the static ring acts, which is usually much more inertial than the static phase of the PLL, the AGC signal slightly increases (if provided), reducing the gain of the 15 PLL and increasing the stability of the system in small O | M. With the end of the transitional processes in the PLL system, the error signal at the output of phase detector 1 will tend to zero, while V-as the signal at the output 20 of phase detector 2 will tend to maximum. The AGC signal will also be maximum (for given voltages at the inputs of phase detectors and a given ratio multiplicity between the frequencies of the oscillators). As the magnification increases, for example, the maximum voltage at the output of phase detector 2 will fall, the AGC signal will also decrease, and the gain of the error signal amplifier 7 will increase. The subject of the invention is a phase locked loop device with automatic gain control, comprising a tunable oscillator connected in a ring, a phase detector whose second input (connected to a reference oscillator, a filter, an error signal amplifier and a control element, and an automatic gain control phase detector connected with its inputs through the phase shifter To the reference generator and directly to the adjustable generator, and the output through the filter to the amplifier of the automatic regulator Application gain, characterized in that, in order to simplify the device while maintaining the stability of the output of the amplifier automatic gain control is connected to the adjustment input of the amplifier error signal.