JPH0531404U - Timing extraction circuit - Google Patents

Abstract

(57) [Abstract] [Object] The present invention, in a cross-connect system or the like in which different transmission signals are input, reduces the number of parts in one differential circuit and a sine wave / rectangular wave conversion circuit, and extracts timing signals There is provided a timing extraction circuit adapted to do so. According to the present invention, there are provided first switches 16 and 17 for controlling signal input and signal output to a timing extraction circuit according to the present invention, and rising and falling of an output signal waveform from the first switch 16. One differentiating circuit 12 for detecting the timing of
And the output signal of the differentiating circuit 12 are input to a parallel connection of two band pass filters 13 and 19 each having a different pass band width, a signal of each frequency is extracted from each filter, and a sine wave / rectangular wave is obtained. The conversion circuit 14 generates a timing signal of logical level from this signal and outputs it as the timing signal 15 via the second switch 17.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a timing extraction circuit used in a cross-connect system for extracting clock timing from NRZ signals having two kinds of signal speeds.

[0002]

[Prior Art]

 Conventionally, in order to realize this main timing extraction electronic circuit, a method of preparing separate timing extraction electronic circuits suitable for each data rate and switching to each circuit as necessary to extract the timing signal has been adopted. Has been. For example, FIG. 2 shows a conventional timing extraction circuit.

In FIG. 2, a signal input as an NRZ signal input 11 is a discontinuous clock signal whose rising and falling timings are detected by differentiating circuits 22 and 12. This discontinuous clock signal is converted into a continuous sine wave by the SAW bandpass filters 13 and 19. Further, a sine wave / rectangular wave conversion circuit 14, 23 is used to generate a logic level timing signal. The clock speed selection signal 25 is predetermined, and either the output of the sine wave / rectangular wave conversion circuit 14 or the sine wave / rectangular wave conversion circuit 23 is selected by the clock speed selection signal 25, and the switch is opened. Output to 117. Further, the switches 16 and 17 cut off the input and output of this circuit by an external control input 18 to output an unnecessary timing signal to the outside and prevent an unnecessary differential signal from being added to the SAW bandpass filter.

[0004]

[Problems to be solved by the device]

 However, in the conventional timing extraction circuit, each of the differentiating circuit, the SAW bandpass filter, and the sine wave / rectangular wave converting circuit must be prepared in accordance with each transmission speed of the input NRZ signal, and there are a plurality of transmission speeds. In the system, the above circuit must be equipped for each transmission speed for each transmission speed. This leads to an increase in the number of parts of the entire device and an increase in external shape, etc., resulting in an increase in the manufacturing cost of the device, an increase in assembly and adjustment time of the entire circuit, and a power consumption of the entire device Is increasing.

An object of the present invention is to eliminate such conventional problems and solve the above-mentioned drawbacks of the prior art.

[0006]

[Means for Solving the Problems]

 Therefore, the first means for solving the above problems of the present invention has a first switch for controlling input of an input signal and a second switch for controlling output of an output signal. In a timing extraction circuit for extracting a timing signal from an NRZ signal, one differentiating circuit for detecting the timing of rising and falling of the output signal waveform of the first switch, and a different band from the output signal of the differentiating circuit. At least two bandpass filters that pass only the width and are connected in parallel with the input terminal and the output terminal respectively, and one sine that generates a timing signal of a logical level from the output signal of the bandpass filter. The wave / rectangular wave conversion circuit and the output of the sine wave / rectangular wave conversion circuit are input to the second switch, and a timing signal is output from the second switch. Characterized in that way the.

Further, a second solution means of the present invention has a first switch for controlling input of an input signal and a second switch for controlling output of an output signal. In a timing extraction circuit for extracting a timing signal from an NRZ signal, one differentiating circuit for detecting the timing of rising and falling of the output signal waveform of the first switch, and a different band from the output signal of the differentiating circuit. A logic-level timing signal is generated from at least two SAW bandpass filters that pass only the width and that have input terminals and output terminals connected in parallel, and the output signals of the SAW bandpass filters. One sine wave / rectangular wave conversion circuit and the output of the sine wave / rectangular wave conversion circuit are input to the second switch, and timing is output from the second switch. It is characterized in that it outputs a signal.

Furthermore, a third solution means of the present invention has a first opening / closing device for controlling input of an input signal and a second switch for controlling output control of an output signal. In the timing extraction circuit for extracting the timing signal from the NR Z signal of the signal, one differential circuit for detecting the rising and falling timing of the output signal waveform of the first switch, and the output signal of the differentiating circuit From at least two band-pass filters that pass only different bandwidths, the signal input to each band-pass filter is controlled by a third switch to which a selection signal is input, Signal output of the control signal is output by the fourth switch to which the selection signal is input, and a single sine wave that generates a logic level timing signal from the output signal of the fourth switch The present invention is characterized in that a rectangular wave conversion circuit and outputs of the sine wave / rectangular wave conversion circuit are input to the second switch, and a timing signal is output from the second switch.

[0009]

[Action]

 In the first solution, the first and second switches control the input of signals to the timing extraction circuit of the present invention and the output of timing signals from the timing extraction circuit of the present invention. Then, the signal from the first switch is detected by the differentiating circuit at the rising and falling edges of the signal waveform, and the detected signal is set for each band set to have a resonance point according to the transmission speed. Limit the bandwidth with a pass filter and take it out. Each output from this bandpass filter is input to one sine wave / rectangular wave conversion circuit to generate a logic level timing signal, which is then output to the second switch and the timing extraction signal output. Control.

In the second solution, the bandpass filter is replaced with a SAW bandpass filter.

According to a third solution, the first and second switches have a signal input to the timing extraction circuit of the present invention and a timing signal output from the timing extraction circuit of the present invention. Control. Then, the signal from the first switch is detected by the differentiating circuit as to the rising and falling of the waveform of the signal, and the detected signal is input to the third switch. A selection signal is used to selectively switch to each of the band pass filters set so as to have a resonance point according to the transmission speed. Then, the band-pass filter to which the signal is input limits the bandwidth and takes it out, and outputs it to the fourth switch. The output of the fourth switch is selectively switched by a selection signal and input to one sine wave / rectangular wave conversion circuit to generate a logic level timing signal, which is further output to the second switch. Control the output of the timing extraction signal.

[0012]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. The same parts as those in the conventional example are designated by the same reference numerals. FIG. 1 is a conceptual diagram showing a cross-connect system to which the present invention can be applied.

In FIG. 1, the signal applied to the system 100 from the input terminal 7 is input to the interface / reception unit 1 and converted into the NRZ signal 3. Then, the NRZ signal 4 that has passed through the matrix switch unit 2 is input to the timing extraction circuit 6 and the interface unit / transmission unit 5, respectively, and this timing extraction circuit 6 outputs the timing clock signal 9 from the NRZ signal 4. Is extracted and output to the interface / transmission unit 5. The interface / transmission unit 5 uses the timing clock signal 9 to perform signal processing such as signal identification of the NRZ signal 4, and then reverse-converts it again into a signal of the same kind as the signal input from the input terminal 7 and outputs it. Output to terminal 8.

FIG. 3 is a basic block diagram showing the structure of the timing extraction circuit 6 in detail. The configuration of FIG. 3 will be briefly described first. The output of the switch 16 to which the NRZ signal input 11 and the external control input signal 18 are input is connected and input to the differentiating circuit 12, and the output of the differentiating circuit 12 is connected to the SAW bandpass filter A13 and the SAW bandpass filter B19. Is entered. The outputs of the two SAW bandpass filters A13 and SAW bandpass filter B19 are both connected and input to the same input terminal of the sine wave / rectangular wave conversion circuit 14, and the output of the sine wave / rectangular wave conversion circuit 14 is a switch. The output of the switch 17 is output as a recovered clock output 15. An external control input signal 18 is input to the switch 17 like the switch 16.

The operation of the above configuration will be described below. The switches 16 and 17 are controlled to open and close by an external control input signal 18, and when the timing extraction circuit 6 is disabled by the external control input signal 18, no signal is sent to the differentiating circuit 12. Neither is input, nor is the recovered clock output 15 output. This prevents an unnecessary signal from being input from the differentiating circuit 12 to the SAW bandpass filter A13 or SAW bandpass filter B19, and at the same time, the erroneous reproduction clock output 15 is output from the opener 17. This is to prevent this. The NRZ signal input 11 is input to the SAW bandpass filter A13 and the SAW bandpass filter B19 as a discontinuous clock signal whose rising and falling are detected by the differentiating circuit 12. Here, the SAW bandpass filter A13 and the SAW bandpass filter B19 have the wiring configuration shown in FIG. 4, and the input and output of each SAW bandpass filter are connected in parallel. The impedance matching coils 20 and 21 are connected between the input and output terminals, respectively, in order to establish a connection matching between the input impedance and the output impedance due to the parallel connection of and the differential circuit 12 at the front stage and the sine wave / rectangular wave conversion circuit 14 at the rear stage. It is connected. The resonance point f1 of the SAW bandpass filter A13 and the resonance point f2 of the SAW bandpass filter B19 correspond to different transmission rates of the NRZ signal input 11. For example, the resonance point f1 is for the D S3 signal. In the present invention, the resonance point f2 is set to 51.8 MHz for the STS-1 signal. The frequencies of the resonance points f1 and f2 are not limited to this.

Since the resonance points of the two SAW bandpass filters are different, a signal corresponding to the transmission speed of the NRZ signal input 11 is a sine wave / rectangle from either the SAW bandpass filter A 13 or the SAW bandpass filter B 19. It is output to the wave conversion circuit 14. The sine wave / rectangular wave conversion circuit 14 generates a logic level signal from the output signal of the SAW bandpass filter and outputs it to the switch 17. The switch 17 is controlled by the external control input signal 18 to be output as the recovered clock output 15.

Although two SAW bandpass filters are shown in the above embodiments, the present invention is not limited to this, and three or more SAW bandpass filters or other bandpass filters such as a crystal filter may be used. Filters may be connected in parallel to match the impedances at the input end and the output end, and the resonance points of the bandpass filters may be different from each other. Further, although the impedance matching coils 20 and 21 are used for impedance matching, they may be composed of other impedance elements such as capacitors, and the impedance matching coils may be connected in parallel. Alternatively, as shown in FIG. 5, the switches 30 and 31 may control signal input and signal output to the SAW bandpass filters 13 and 19, respectively. In this case, the switching of the signals of the switches 30 and 31 is controlled by the clock speed selection signal 25.

[0018]

[Effect of the device]

 As described above, according to the present invention, in a timing extraction circuit of a cross-connect system in which transmission signals having different transmission rates are input, a plurality of bandpass filters having resonance points corresponding to the different transmission rates are provided. By incorporating it and using a differential circuit and a sine wave / rectangular wave converter circuit one by one, the number of components of the entire timing extraction circuit could be reduced. For this reason, it is possible to reduce the size of the entire system. Moreover, the reduction in the number of parts reduces power consumption, and also has an excellent effect that labor saving such as circuit adjustment at the time of production can be brought about. There is.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a cross-connect system to which the present invention can be applied.

FIG. 2 is a diagram showing a conventional example.

FIG. 3 is a diagram showing an embodiment of the present invention.

FIG. 4 is a connection configuration diagram of two SAW bandpass filters used in one embodiment of the present invention.

FIG. 5 is a diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 1 Interface / Reception Part 2 Matrix / Switch Part 3, 4, 11 NRZ Signal 5 Interface / Transmission Part 6 Timing Extraction Circuit 7 Input Terminal 8 Output Terminal 12 Differentiation Circuit 13 SAW Bandpass Filter A 14 Sine / Square Wave Conversion Circuit 15 Reproduced clock output 16, 17, 30, 31 Switch 18 External control input signal 19 SAW bandpass filter B 20, 21 Impedance matching coil 22 Differentiation circuit 23 Sine wave / rectangular wave conversion circuit 24 Switching circuit 25 Clock speed selection signal

Claims (3)

[Scope of utility model registration request] 1. A first switch which controls input of an input signal, and a second switch which controls output of an output signal,
In a timing extraction circuit for extracting a timing signal from the NRZ signal of the input signal, one differentiation circuit that detects the timing of the rising and falling edges of the output signal waveform of the first switch, and the output signal of the differentiation circuit To pass only different bandwidths, and at least two band pass filters each having an input terminal and an output terminal connected in parallel, and a logic level timing signal is generated from the output signals of the band pass filters. A sine wave / rectangular wave conversion circuit, wherein the output of the sine wave / rectangular wave conversion circuit is input to the second switch, and a timing signal is output from the second switch. A timing extraction circuit characterized by. 2. The timing extraction circuit according to claim 1, wherein the bandpass filter is a SAW bandpass filter. 3. A third switch for controlling the signal input to each of the band pass filters by an input selection signal, and the selection signal to be input the signal output from each of the band pass filters. 4. The timing extraction circuit according to claim 1, further comprising a fourth switch controlled by.