JPH04134935A - Optical timing oscillator - Google Patents

Abstract

PURPOSE:To obtain an oscillating frequency with high stability and a wide variable range by using the optical transmission time of an optical cable as an oscillation synchronization time and modulating the oscillating frequency only with the adjustment of the length of the optical cable. CONSTITUTION:An electric signal being an output of an inverter 1 is converted into an optical signal by using an E/O converter(electrooptic converter) 16, the optical signal is given to an optical cable, the optical transmission time of the optical cable is used as an oscillation synchronization time and an O/E converter(optoelectric converter) 19 to convert the optical signal into an electric signal, it is inputted to the inverter, from which a highly stable oscillating frequency is outputted. In this case, since the oscillating frequency is modulated by having only to adjust the length of the optical cable, the oscillating frequency with a wide variable range and high stability is easily obtained, and since the E/O converter 16 is used for the optical transmission of the optical cable, when an E/O converter 16 capable of outputting a parallel output is employed, both the optical output and the electric output with matched phase are obtained as the oscillator output. Thus, the economical, highly stable and rational optical timing oscillator with high application performance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an optical/electrical optical timing oscillator that oscillates a variable frequency with high stability.

(Conventional Technique IN) Conventionally, a crystal oscillator is generally used as a highly stable oscillator. An example of the configuration of a conventional crystal oscillator is shown in FIG.

In Fig. 3, the input and output of the inverter 1 are connected through a resistor 3, and the input voltage of the inverter 1 is set to a threshold Sv.
is used as an amplifier circuit. Further, the output voltage of the inverter 1 is inputted to the crystal resonator 7 through a filter consisting of a resistor 4 and a capacitor 6. This filter is provided to make the voltage close to a sine wave, since stability will be lost if the square wave output voltage of the inverter 1 is directly applied to the crystal resonator 7.

The crystal oscillator 7 generally has an extremely sharp resonant frequency of about several MHz, and at this resonant frequency, the reactance of the crystal oscillator 7 becomes minimum, and the output voltage of the crystal oscillator 7 is transferred to an amplifier circuit consisting of an inverter 1 and a resistor 3. I am inputting a stable frequency.

Further, the crystal oscillator shown in FIG. 3 has the following circuit added as a VCO (voltage controlled oscillator) for modulating the oscillation frequency.

That is, a voltage of O to IOV, for example, is applied as a control voltage 9 for controlling the oscillation frequency with voltage, and this control voltage 9 is applied as a DC bias voltage to a varicap (variable capacitance diode) 11 through a load resistor /O. ,
It is connected to the crystal resonator 7 through a capacitor 12 for cutting the DC component.

By changing the load capacitance of the crystal oscillator 7, the voltage oscillation output 13 can be adjusted to several MHz, which is the natural frequency of the crystal oscillator 7.
It is possible to change z by approximately 1%.

Next, the operation of the crystal oscillator shown in FIG. 3 will be explained using the time chart shown in FIG. 4.

For example, when a voltage signal 2 output from an inverter 1 rises, this voltage signal 2 passes through a filter consisting of a resistor 4 and a capacitor 6 and becomes a voltage signal 5 close to a sine wave, and as the voltage level increases, the crystal oscillator 7 The resonance frequency is determined by the crystal oscillator 7 and the varicap 11 whose capacitance changes depending on the control voltage 9. Due to this resonance phenomenon, a voltage signal 8 of a clean sine wave is lowered in voltage level and connected to the inverter 1. The signal is input to an amplifier circuit consisting of a resistor 3.

When the voltage signal 8 gradually rises due to the resonant frequency and reaches a logic high level above the threshold 87 of the inverter 1, the inverter 1 inverts the signal below the threshold Sv after a falling signal processing time T3 for inverting this signal. A voltage signal 2 at a certain logic L level is output.

This voltage signal 2 passes through a filter consisting of a resistor 4 and a capacitor 6 to become a voltage signal 5 close to a sine wave, and is input to a crystal resonator 7 while decreasing the voltage level.

Due to the resonance phenomenon of the resonance frequency caused by the crystal resonator 7 and the capacitance of the varicap 11, a clean sine wave voltage signal 8 is outputted, and is inputted to the amplifier circuit consisting of the inverter 1 and the resistor 3 while increasing the voltage level. Ru.

The voltage signal 8 then falls at the resonant frequency mentioned above.

When the logic L level is below the threshold S■ of the inverter 1, the inverter 1 outputs the voltage signal 2 at the logic H level, which is above the threshold 87, after a rising signal processing time T5 for inverting this signal.

By repeating the above operations in sequence and changing the control voltage 9 of several MHz, which is the natural frequency of the crystal oscillator 7, it is possible to modulate the frequency signal 2 by approximately 100%, and obtain a highly stable frequency signal 2. can.

(Problems to be Solved by the Invention) However, the above conventional circuit has the following problems.

In other words, although a crystal oscillator is used as a highly stable oscillator, the variable range of the oscillation frequency is limited to a few percent of the natural frequency of the crystal resonator, which is several MHz.
The variable frequency range is narrow, and if it is too wide, the oscillation operation becomes unstable.

Therefore, if you want to modulate the oscillation frequency beyond its variable range, you will need to replace the entire crystal oscillator.

It is disadvantageous in terms of applicability and economy.

The present invention provides a rational optical timing oscillator that uses the optical transmission time of an optical cable as the oscillation synchronization time and modulates the oscillation frequency only by adjusting the length of the optical cable, thereby solving the problems of conventional devices. It is an object.

[Structure of the invention]

(Means and effects for solving problem 11) The present invention converts the output of an inverter from an electrical signal to an optical signal using an E/O converter (electrical/optical converter), and passes this optical signal through an optical cable. The optical cable's optical transmission time is used as the oscillation synchronization time, and an O/E converter (optical/electrical converter) is used to convert the optical signal into an electrical signal, which is input to an inverter to generate a highly stable oscillation frequency. This is an optical timing oscillator that outputs oscillation frequency, and the oscillation frequency can be modulated by adjusting only the length of the optical cable, thereby providing a highly stable oscillation frequency with a wide variable range.

(Embodiment) An embodiment of the optical timing oscillator according to the present invention is shown in FIG.

In FIG. 1, a voltage signal 15 output from an inverter 1 is input to an E/O converter 16 that converts an electrical signal into an optical signal, and an optical signal 1 corresponding to the output voltage of the inverter 1 is input to an E/O converter 16.
7 and 21 are output in parallel.

The optical signal 17 is connected to an optical cable 18 used as the oscillation cycle time.
The optical transmission time depending on the length of the optical cable 18 is used as the oscillation cycle time, the length of the optical cable 18 is adjusted according to the oscillation frequency, and the signal is input to the O/E converter 19.

The 0/E converter 19 converts the optical signal 17 into a corresponding electric signal and outputs a voltage signal 20, and the inverter 1 inputs this voltage signal 20 and inverts the voltage level of the voltage signal 20 to generate a voltage signal 15. Output.

In this way, as the voltage signal 15 from the inverter 1 and the optical signal 21 from the E/O converter 16, electrical signals and optical signals of high frequency and in phase are obtained with high stability.

Next, the operation of the optical timing oscillator shown in FIG. 1 will be explained using the time chart shown in FIG.

For example, when the voltage signal 15 output from the inverter 1 rises to a logic H level higher than the threshold 87,
The E/○ converter 16 outputs a logical H level optical signal 17 after a rising signal processing time T1 for converting the voltage signal 15 into an optical signal 17.

The optical signal 17 passes through the optical cable 18 and is input to the O/E converter 19 after an optical transmission time depending on the length of the optical cable 18, and the O/E converter 19 converts the input optical signal 17 into a voltage signal 20. After the rising signal processing time, a voltage signal 20 of logic H level is output.

The time T2 is the sum of the optical transmission time within the optical cable 18 and the processing time of the O/E converter 16.

The inverter 1 receives a logic H level voltage signal 20,
After a falling signal processing time T3 for inverting this signal, a voltage signal 15 of logic L level, which is less than the threshold Sv, is output. Further, the E/O converter 16 outputs the optical signal 1 at the logical L level after a falling signal processing time T4 for converting the voltage signal 15 which has fallen to the logical L level into the optical signal 17.
Outputs 7.

The optical signal 17 is input to the O/E converter 19 after an optical transmission time depending on the length of the optical cable 18, and the O/E converter 19 converts the input optical signal 17 into a voltage signal 20 as a falling signal. After the processing time, a logic L level voltage signal 20 is output.

The inverter 1 inputs a logic L level voltage signal 20,
After a rising signal processing time T5 for inverting this signal, a logic H level voltage signal 2 is output.

By repeating the above operations sequentially and using the optical transmission time of the optical cable 18 as the oscillation cycle time, the voltage signal 15 and the optical signal 21 in phase are outputted to the voltage oscillation output 13 as a frequency with a wide modulation range and high stability. and can be obtained from the optical oscillation output 14.

〔Effect of the invention〕

As explained above, according to the present invention, the oscillation frequency can be modulated simply by adjusting the length of the optical cable, so it is possible to easily obtain a highly stable oscillation frequency with a wide variable range. /○ Since we are using a converter,
By using an E/O converter capable of parallel output, both phase-matched optical output and electrical output can be obtained as the oscillator output, making it highly applicable, economical, and highly stable. A reasonable optical timing oscillator can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the optical timing oscillator according to the present invention, Fig. 2 is a time chart diagram for explaining the operation of the device shown in Fig. 1, and Fig. 3 shows an example of a conventional oscillator. The configuration diagram and FIG. 4 are time charts for explaining the operation of FIG. 3. 1... Inverter 2, 15... Inverter output voltage signal 3.4, /O... Resistor 5...
・Crystal resonator input voltage signal 6.12...Capacitor
7...Crystal resonator 8...Resonance voltage signal 9
...Control voltage 11...Varicap 13...
・Voltage oscillation output 14...8 optical oscillations 16-・
・E/O converter 17.21... Optical signal 18.
22... Optical cable 19... O/E converter
2o...O/E converter output voltage signal agent Patent attorney
Nori Chika Nori Yasushi sheep illustration

Claims (1)

[Claims] An E/O converter inputs the electrical signal output from the inverter, converts it into an optical signal, and outputs it to the optical cable; and an E/O converter that transmits the optical signal output from the E/O converter to the O/E converter; An optical timing oscillator comprising: an optical cable in which optical transmission time is used as an oscillation cycle time; and an O/E converter that inputs an optical signal from the optical cable, converts it into an electrical signal, and outputs it as input to the inverter. .