JPH0197018A - Signal generating circuit - Google Patents

Abstract

PURPOSE:To realize a signal generating circuit with high responsiveness by calculating a signal relating to a phase difference or a frequency difference of both input/output signals, a signal relating to the history and a signal relating to a time serial change of the phase difference or the frequency difference, and using the result as a control signal. CONSTITUTION:An input signal (pulse signal) IS and a feedback signal FBS of an output signal OS being objects of an output are supplied to a phase comparator 1, and a pulse signal corresponding to the phase difference or the frequency difference of the both, that is, a phase difference signal or a frequency difference signal is supplied to an arithmetic unit 6 and a history storage circuit 5. An accumulating circuit 52 outputs a signal corresponding to the accumulated value to the arithmetic unit 6. A varying amount calculator 7 calculates a difference between the present DELTAphiand the DELTAphi at one preceding sample time and feeds it to the arithmetic unit 6. The arithmetic unit 6 adds three inputs, that is, an output of the phase comparator 1, an output of the history holding circuit 5 or the accumulating circuit 52 and an output of the varying amount calculator 7, outputs a voltage signal corresponding to the result to a VCO 3, which outputs an output signal (pulse signal) having a frequency corresponding to the said voltage signal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a signal generation circuit, and in particular proposes a signal generation circuit that can quickly obtain a target frequency by improving the establishment of synchronization between two signals. It is something.

[Conventional technology]

Figure 4 is a block diagram of a conventional phase-locked loop, in which a phase comparator 1 whose input is an input signal (norse signal) S and a feedback signal (pulse signal error BS) corresponds to the phase difference of the re-input signal. This output signal is input to a low-pass filter 2, and a voltage signal corresponding to the phase difference is output from the low-pass filter 2. This voltage signal is input to a voltage controlled oscillator (VCO) 3 and is input to the VC
O3 outputs a pulse signal with a frequency corresponding to the voltage of this input signal.

This output signal OS is frequency-divided by N in a frequency divider 4, and the frequency-divided output is used as the feedback signal FBS.

[Problem that the invention seeks to solve]

In a circuit with such a configuration, if the phase difference between the input signal IS and the feedback signal FBS is large, the response of the system tends to become oscillatory, which poses a problem in that it is difficult to quickly obtain a stable synchronized state. .

The present invention has been made to solve this problem, and it is possible to suppress vibration and quickly obtain a synchronized state by using the history of the phase difference or frequency difference output by the phase comparator. The purpose is to provide a signal generation circuit that can

Means for Solving Problem c] The signal generation circuit according to the present invention generates a signal related to a phase difference or a frequency difference between human and output signals, a signal related to the history thereof, and a time series of the phase difference or frequency difference. The sum of signals related to the amount of change in the target is calculated, and the calculated output is used as a control signal for the output signal.

[Effect]

The above-mentioned sum acts to suppress the correction of the phase difference or the frequency difference, and as a result, vibrations are suppressed.

[Examples]'' The present invention will be described in detail below based on drawings showing examples thereof.

FIG. 1 is a block diagram of a signal generation circuit according to the present invention. The phase comparator 1 receives the target input signal (pulse signal) Is and the feedback signal F of the output signal O8.
BS is input, and a pulse signal corresponding to the phase difference or frequency difference between the two, that is, a phase difference signal or a frequency difference signal, is input to the calculator 6 and the history holding circuit 5. The history holding circuit 5 includes a holding circuit 51 that sequentially holds phase difference signals Δφ and an accumulation circuit 52 that accumulates i phase difference signals Δφ held by this holding circuit 51. The accumulation circuit 52 calculates a signal directly corresponding to ΣΔφ. Emit to vessel 6.

The output of the holding circuit 51 is input to the change amount calculator 7, and the change amount calculator 7 calculates the current Δφ and Δ1 sample timing before.
The difference with φ is calculated and given to the arithmetic unit 6.

The arithmetic unit 6 has three inputs: the output of the phase comparator 1, the output of the history holding circuit 5 or the accumulation circuit 52, and the change amount calculator 7.
and the output of , and a voltage signal corresponding to this is output. This voltage signal is applied to VCO3, resulting in VCO
3 emits an output signal (pulse signal) OS having a frequency corresponding to the voltage signal.

This output signal O3 is frequency-divided by N by a frequency divider 4 and given to the phase comparator 1 as a feedback signal FBS.

Next, it will be explained how vibrations are suppressed using such a circuit.

FIG. 3 is a characteristic diagram showing temporal changes in the output signal or feedback signal in the conventional circuit shown in FIG. 4, and shows the difference a from the phase of the target value shown by the straight line.

b etc. become control signals for the VCO3.

Since this difference is updated each time the control is performed, it enters the oscillating system before it asymptotically approaches the target value.

It is.

FIG. 2 is a corresponding characteristic diagram of the circuit of the invention.

Assuming that the output signal or feedback signal changes as shown by the broken line in the figure, the phase difference signal at 1n-IN t,1 is Δφ, -1. It becomes Δφ7. In the circuit of FIG. 4, only Δφゎ is used, but in the circuit of the present invention, Δφ7
, Δφ, -Δφa-1, Δφ7゜Δφ7-1...
The cumulative value of As a result, a smaller correction than the correction by Δφ7 is performed, and as a result, asymptotically approaches the target value without vibration or with small vibration, as shown by the solid line in FIG.

Note that the history holding circuit 5. The change amount calculator 7 is an analog circuit,
It can be constructed using any digital circuit.

〔Effect of the invention〕

As described above, the circuit of the present invention retains the history of the phase difference 1 frequency difference and reflects this in the oscillation frequency control, so the correction of the phase difference 9 frequency difference is suppressed, and as a result, vibrations are also suppressed and the Reach target value. Therefore, a signal generating circuit with high responsiveness can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a characteristic diagram for explaining its operation, FIG. 3 is a characteristic diagram of a conventional circuit, and FIG. 4 is a block diagram of the conventional circuit. 1... Phase comparator 3... VCO4... Frequency divider 5
...History holding circuit 7...Change amount calculator 51...
Holding circuit 52...Accumulation circuit In the figures, the same reference numerals indicate the same or corresponding parts. Agent Masu Oiwa Yuke 2 ■ 1!1 3rd Σ

Claims (1)

[Claims] 1. In a signal generation circuit configured to synchronize the two signals by detecting the phase difference or frequency difference between the input signal and the fed-back output signal in time series, the phase difference or frequency difference between the input signal and the output signal is detected. A circuit that maintains the history of
A circuit that calculates the amount of change over time in the phase difference or frequency difference, and a circuit that calculates the sum of a signal related to the history, a signal related to the amount of change, and a signal related to the phase difference or frequency difference. A signal generating circuit characterized in that the output of the circuit is used as a control signal for an output signal.