JPH06338773A - Bipolar clock disturbance detection circuit - Google Patents

Abstract

PURPOSE:To detect the disturbance of a bipolar clock without using a phase locked oscillation circuit and to switch a reference clock before the influence of disturbance is applied to a following circuit, etc. CONSTITUTION:A positive polarity pulse detection circuit 1 outputs a signal S1 in which only the positive polarity pulse of an input bipolar clock is sampled, and a negative polarity pulse detection circuit 2 outputs a signal S2 in which only the negative polarity pulse of the input bipolar clock is sampled. A counter 3 counts up by clocking the output signal S1 of the positive polarity pulse detection circuit 1, and a counter 4 counts up by clocking the output signal S2 of the negative polarity pulse detection circuit 2. A comparator 5 issues an alarm when either the count results of the counters 3, 4 exceeds a threshold value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bipolar clock disturbance detection circuit, and more particularly to a disturbance detection circuit for excessive pulses or missing pulses of a bipolar clock.

[0002]

2. Description of the Related Art Generally, in a bipolar clock, as shown in FIG. 2, since a main clock indicates a reference phase in the apparatus, a sub clock, which is an even division of the main clock, is superimposed by bipolar violation.

Conventionally, a bipolar clock disturbance detection circuit of this type, as shown in FIG. 3, detects only a positive pulse from a bipolar clock, outputs a bipolar / unipolar converted positive polarity pulse detection circuit 1, and a bipolar pulse detection circuit 1. Only negative polarity pulse is detected from the clock, and bipolar /
It has a negative polarity pulse detection circuit 2 that outputs by unipolar conversion.

Further, the bipolar clock disturbance detection circuit receives the outputs of the positive polarity pulse detection circuit 1 and the negative polarity pulse detection circuit 2 and extracts a reference phase instruction signal, and a bipolar violation detection circuit 6 and the reference phase instruction circuit. It has a phase-locked oscillation circuit 7 which issues phase-out alarm in synchronization with the signal.

The positive polarity pulse detection circuit 1 inputs a bipolar clock and outputs a signal S1 of only positive polarity pulses,
The negative polarity pulse detection circuit 2 inputs a bipolar clock and outputs a signal S2 of only negative polarity pulses.

The bipolar violation detection circuit 6 inputs the signal S1 of only the positive pulse from the positive pulse detection circuit 1 and the signal S2 of only the negative pulse from the negative pulse detection circuit 2, and these signals S1 , S2 detects the bipolar violation to output the reference phase indicating signal. The phase-locked oscillator circuit 7 receives this reference phase instruction signal, establishes the phase lock, and issues an alarm when the phase lock is lost.

[0007]

In the above-mentioned conventional bipolar clock disturbance detection circuit, since the disturbance of the bipolar clock is detected by using the phase-locked oscillation circuit, the circuit scale becomes large and the disturbance of the bipolar clock becomes large. On the other hand, there is a problem that the alarm is not issued when the phase synchronization is achieved.

Therefore, an object of the present invention is to solve the above problems and to detect a disturbance of a bipolar clock without using a phase-locked oscillator circuit. Before the influence of the disturbance reaches a circuit in a subsequent stage, the reference clock can be detected. It is an object of the present invention to provide a bipolar clock disturbance detection circuit capable of switching between the two.

[0009]

A bipolar clock disturbance detecting circuit according to the present invention comprises a positive pulse detecting means for detecting a positive pulse from a bipolar signal and a negative pulse detecting means for detecting a negative pulse from the bipolar signal. A positive pulse counting means for counting the positive pulse detected by the positive pulse detecting means, and a negative pulse counting means for counting the negative pulse detected by the negative pulse detecting means, Determination means for determining whether or not the difference between the count value of the positive polarity pulse counting means and the count value of the negative polarity pulse counting means is equal to or greater than a preset threshold value, and the positive polarity pulse counting by the determination means Means for issuing a warning of loss of phase synchronization when it is determined that the difference between the count value of the means and the count value of the negative polarity pulse counting means is equal to or more than the threshold value. Eteiru.

[0010]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, a bipolar clock disturbance detection circuit includes a positive polarity pulse detection circuit 1 that detects only positive polarity pulses from a bipolar signal, a negative polarity pulse detection circuit 2 that detects only negative polarity pulses from a bipolar signal,
A counter 3 for counting the output signal S1 of the positive pulse detection circuit 1 and an output signal S2 of the negative pulse detection circuit 2
A counter 4 that counts a counter, and a comparator circuit 5 that issues an alarm when the difference between the counters 3 and 4 exceeds a predetermined threshold value.
It has a bipolar violation detection circuit 6 which receives the output signal S1 of the positive polarity pulse detection circuit 1 and the output signal S2 of the negative polarity pulse detection circuit 2 and extracts a reference phase instruction signal.

The operation of the embodiment of the present invention will be described with reference to FIG. The positive pulse detection circuit 1 is a signal S1 obtained by extracting only the positive pulse of the input bipolar clock.
And the negative pulse detection circuit 2 outputs a signal S2 obtained by extracting only the negative pulse of the input bipolar clock.

The counter 3 counts up with the output signal S1 of the positive polarity pulse detection circuit 1 as a clock, and the counter 4 counts up with the output signal S2 of the negative polarity pulse detection circuit 2 as a clock. These counters 3 and 4 are simultaneously reset at a predetermined timing.

The comparison circuit 5 inputs the counting results of the counters 3 and 4 and compares these counting results. Counters 3 and 4
Are counted up alternately, the counter 3,
The counting result of 4 does not shift more than the shift due to the bipolar violation.

However, when a disturbance occurs in the input bipolar clock and a surplus pulse is mixed in the positive polarity pulse, the counter 3 counts more surplus pulses than in a normal time within a fixed time. The deviation from the counting result of 4 is detected.

If the threshold value including the deviation of the counters 3 and 4 due to the bipolar violation in the normal state is set in advance in the comparison circuit 5, the deviation of the counting result in the above case exceeds the threshold value. Gives an alarm.

Further, even when a surplus pulse is mixed in the negative polarity pulse, the counter 4 counts more surplus pulses than in a normal time within a fixed time, so that the comparison circuit 5 issues an alarm.

Similarly, when the positive polarity pulse or the negative polarity pulse is missing due to the disturbance of the input bipolar clock, the counter 3 or the counter 4 counts less than the normal time, and the comparator circuit 5 issues an alarm. Is issued.

In this way, the positive polarity pulse and the negative polarity pulse of the bipolar clock are individually counted by the counters 3 and 4, and when the deviation of the counting results of these counters 3 and 4 exceeds a predetermined threshold value, the comparison circuit. By issuing an alarm from 5, the disturbance of the bipolar clock can be detected without using the phase-locked oscillation circuit, and the reference clock can be switched before the influence of the disturbance reaches the circuit in the subsequent stage. .

Further, since the disturbance of the bipolar clock is detected by using the counters 3 and 4 and the comparison circuit 5, the circuit scale can be made smaller than that of the conventional detection circuit using the phase-locked oscillation circuit.

[0021]

As described above, according to the present invention, the positive polarity pulse and the negative polarity pulse of the bipolar signal are individually counted, and when the difference between these count values exceeds a preset threshold value, the phase By issuing an out-of-synchronization alarm, the disturbance of the bipolar clock can be detected without using a phase-locked oscillator circuit, and the reference clock can be switched before the influence of the disturbance reaches the circuit in the subsequent stage. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing waveform examples of a bipolar clock, a signal having only positive polarity pulses, and a signal having only negative polarity pulses.

FIG. 3 is a block diagram showing a configuration of a conventional example.

[Explanation of symbols]

 1 Positive pulse detection circuit 2 Negative pulse detection circuit 3, 4 Counter 5 Comparison circuit

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[Procedure amendment]

[Submission date] December 17, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Claims (1)

[Claims] 1. A positive polarity pulse detection means for detecting a positive polarity pulse from a bipolar signal, a negative polarity pulse detection means for detecting a negative polarity pulse from the bipolar signal, and the positive polarity detected by the positive polarity pulse detection means. Positive pulse counting means for counting the positive pulse, negative pulse counting means for counting the negative pulse detected by the negative pulse detecting means, count value of the positive pulse counting means and the negative pulse Determination means for determining whether or not the difference between the count value of the counting means and the preset threshold value or more,
And a means for issuing an alarm of out-of-phase synchronization when the difference between the count value of the positive polarity pulse counting means and the count value of the negative polarity pulse counting means is determined to be the threshold value or more by the determination means. Characteristic bipolar clock disturbance detection circuit.