KR200304941Y1 - Circuit for improving depth function of modulation and an optic transceiver having the same - Google Patents

Abstract

The present invention relates to a modulation depth performance improving circuit and an optical transceiver including the same, and the modulation depth performance improving circuit inputs an RF signal having an original signal and an IM signal, and separates and outputs the RF signal having the first and second signals. part; A first amplifier amplifying the first signal; An automatic gain control unit which constantly controls the gain of the second signal; A harmonic generator for amplifying the magnitude of the IM signal included in the output signal of the automatic gain controller to be close to the original signal; A first attenuator configured to attenuate the output signal of the harmonic generator to a predetermined size; A phase adjuster for converting the output signal of the first attenuator 180 degrees; A delay unit for delaying the output signal of the first amplifying unit so that the phase of the output signal of the first amplifying unit and the phase of the output signal of the phase adjusting unit are 180 degrees apart; And a coupling unit combining the output signal of the delay unit and the output signal of the phase adjusting unit to output an RF signal from which the IM signal has been removed, thereby improving linearity of the optical transceiver having a modulation depth performance improving circuit.

Description

Circuit for improving depth function of modulation and an optic transceiver having the same

The present invention relates to a modulation depth performance improving circuit and an optical transceiver including the same, and more particularly, to a modulation depth performance improving circuit and an optical transceiver including the same, which improve the modulation depth of an RF signal ranging from several hundred megahealth to a gigahealth band. .

The optical transceiver receives a radio frequency (RF) signal, converts it into an optical signal, transmits it through an optical path, and converts an optical signal received through the optical path back into an RF signal. Optical transceivers are commonly used in optical repeaters in cell phones and optical conversion circuits in analog equipment.

Companies developing such optical transceivers mainly focus on the development of digital optical transceivers and not on the development of analog optical transceivers. In Korea, most of the wireless communication market uses analog optical transceivers, and it is estimated that the time when the analog optical transceivers will be replaced by digital optical transceivers will be about 2010 or later. In the meantime, the use of analog optical transceivers will continue.

Conventional analog optical transceivers have circuitry with improved modulation depth only in the hundreds of megahertz frequency bands, but no circuits with improved modulation depth for hundreds of megahertz gigahertz frequency bands.

Accordingly, the technical problem to be achieved by the present invention is to provide a modulation depth performance improving circuit with improved modulation depth in the gigahealth frequency band from several hundred megahealth.

Another technical task of the present invention is to provide an optical transceiver in which the RF signal is linear and operates stably regardless of temperature change.

A brief description of each drawing is provided to more fully understand the drawings, which are incorporated in the detailed description of the invention.

1 is a block diagram of a modulation depth performance improving circuit according to the present invention.

FIG. 2 shows timing pulses of an RF signal input to the modulation depth performance improving circuit of FIG. 1.

3A illustrates a transfer function characteristic of a signal output from the phase adjuster of FIG. 1.

3B and 3C show timing pulses of a signal output from the phase adjuster of FIG. 1, respectively.

FIG. 3D illustrates a transfer function characteristic of a signal output from the delay unit of FIG. 1.

3E illustrates timing pulses of a signal output from the delay unit of FIG. 1.

FIG. 3F illustrates a transfer function characteristic of a signal output from the combiner of FIG. 1.

3G and 3H show timing pulses of a signal output from the combiner of FIG. 1, respectively.

4 is a block diagram of an optical transceiver according to the present invention.

The present invention to achieve the above technical problem,

A signal separator for inputting an RF signal having an original signal and an IM signal, separating the first signal into a first signal and a second signal; A first amplifier amplifying the first signal; An automatic gain control unit which constantly controls the gain of the second signal; A harmonic generator for amplifying the magnitude of the IM signal included in the output signal of the automatic gain controller to be close to the original signal; A first attenuator configured to attenuate the output signal of the harmonic generator to a predetermined size; A phase adjuster for converting the output signal of the first attenuator 180 degrees; A delay unit for delaying the output signal of the first amplifying unit so that the phase of the output signal of the first amplifying unit and the phase of the output signal of the phase adjusting unit are 180 degrees apart; And a combiner configured to combine the output signal of the delay unit and the output signal of the phase adjuster to output an RF signal from which the IM signal has been removed.

Preferably, the automatic gain control unit includes a second attenuator for attenuating the second signal; A second amplifier for amplifying the IM signal included in the output signal of the second attenuator largely and amplifying the original signal small; A coupler for extracting a part of the output signal of the second amplifier; And a detector configured to detect a phase and a level of the output signal of the coupler and feed the feedback to the second attenuator.

Preferably, it is also connected to the detector, the first attenuator, the phase adjuster and the delay unit, and inputs the output signal of the detector and controls the degree of attenuation of the first attenuator according to the phase and level of the output signal of the coupler. A control unit for controlling the degree of delay of the delay unit according to the phase of the output signal of the phase adjuster such that the phase of the output signal of the delay unit and the output signal of the phase adjuster is 180 degrees; And a third attenuating unit which attenuates and delivers the first amplifying unit.

The present invention to achieve the above other technical problem

A modulation depth performance improving circuit for inputting an RF signal having an original signal and an IM signal, and removing and outputting an IM signal included in the RF signal; An optical converter for converting an RF signal output from the modulation depth performance improving circuit into an optical signal; An optical signal driving and monitoring unit for monitoring an optical signal output from the optical converter and controlling the size of the optical signal to be constant; An optical signal temperature controller for controlling the optical signal to be always constant regardless of temperature change; An RF converter which receives an optical signal output from the optical converter and converts the optical signal into an RF signal; An RF signal driving and monitoring unit for monitoring the RF signal output from the RF converter and controlling the size of the RF signal to be constant; And an amplifier configured to amplify the RF signal output from the RF converter.

The linearity of the optical transceiver is improved by the present invention.

In order to fully understand the present invention, the operational advantages of the present invention, and the objectives achieved by the practice of the present invention, reference should be made to the accompanying drawings that illustrate preferred embodiments of the present invention and the contents set forth in the accompanying drawings.

Hereinafter, the present invention will be described in detail by explaining preferred embodiments of the present invention with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

1 is a block diagram of a modulation depth performance improving circuit according to the present invention. Referring to FIG. 1, the modulation depth performance improving circuit 101 may include a signal separator 111, a third attenuator 121, a first amplifier 131, a delay unit 141, and an automatic gain controller 151. And a harmonic generator 161, a first attenuator 171, a phase adjuster 181, a controller 191, and a coupler 195.

The signal separator 111 inputs a radio frequency (RF) signal RF1, and separates the RF signal into a first signal RF2 and a second signal RF3. The RF signal RF1 has an original signal 211 and an IM (InterModulation) signal 221 as shown in FIG. 2, and the size of the IM signal 221 is very small. The RF signal RF1 shown in FIG. 2 is a signal having two channels. The first signal RF2 and the second signal RF3 are separated in the same magnitude. The RF signal RF1 is an analog signal in the hundreds [MHz] to several [GHz] bands.

The third attenuator 121 attenuates the magnitude of the first signal RF2 and transfers the magnitude of the first signal RF2 to the first amplifier 131. The original signal and the IM signal included in the first signal RF2 by the third attenuator 121 are reduced at a constant ratio.

The first amplifier 131 amplifies the first signal RF2 by a predetermined level. The amplification degree of the first amplifier 131 is determined at design time.

The automatic gain control unit 151 constantly controls the gain of the second signal RF3. The automatic gain controller 151 is configured to amplify the IM signal included in the output signal of the second attenuator 153 and the second attenuator 153 to attenuate the second signal RF3, and to amplify the original signal to a small amount. 2 amplifying unit 155, a coupler 157 for extracting a part of the output signal of the second amplifying unit 155, and detects the phase and level of the output signal of the coupler 157 to the second attenuator 153. The detection part 159 which feeds back is provided. When the level of the output signal of the coupler 157 increases, the second attenuator 153 attenuates a large amount of the second signal RF3. When the level of the output signal of the coupler 157 decreases, the second attenuator 153 The second signal RF3 is attenuated less. Therefore, even though the size of the RF signal RF1 changes, the size of the signal output from the coupler 157 is kept constant and is input to the harmonic generator 161.

The harmonic generator 161 greatly amplifies the IM signal included in the output signal of the coupler 157 so as to approximate the original signal.

The first attenuator 171 attenuates the output signal of the harmonic generator 161 to a predetermined size. Therefore, the IM signal included in the signal output from the first attenuator 171 is much larger than the IM signal 221 of FIG. 2 included in the RF signal RF1, and is an output signal of the first attenuator 171. The original signal included in is very small compared to the original signal (211 of FIG. 2) of the RF signal RF1.

The phase adjuster 181 converts the output signal of the first attenuator 171 by 180 degrees.

The delay unit 141 delays the output signal of the first amplifier 131 so that the phase of the output signal of the first amplifier 131 and the phase of the output signal of the phase adjuster 181 are 180 degrees apart.

The combiner 195 combines the output signal of the delay unit 141 and the output signal of the phase adjuster 181 and outputs the IM signal (221 in FIG. 2) included in the RF signal RF1 and removes the original signal ( Only 211 of FIG. 2 is output. In some cases, as illustrated in FIG. 3C, the IM signal (353 of FIG. 3C) included in the output signal RF5 of the phase adjusting unit 181 is an IM signal in which the delay unit 141 is included in the output signal RF4. (363 in FIG. 3E). Then, the IM signal (383 of FIG. 3H) included in the output signal RF6 of the coupling unit 195 is 180 degrees different from the IM signal (221 of FIG. 2) included in the RF signal RF1, and has a predetermined size. Have By doing so, even if an IM signal is generated at a later stage, the RF signal RF6 output from the modulation depth performance improving circuit 101 is not affected.

The controller 191 is connected to the detector 159, the first attenuator 171, the phase adjuster 181, and the delay unit 141. The controller 191 inputs the output signal of the detector 159 and controls the degree of attenuation of the first attenuator 171 according to the phase and level of the output signal of the coupler 157. That is, when the level of the output signal of the coupler 157 increases, the control unit 191 causes the first attenuator 171 to attenuate a large amount of the output signal of the harmonic generator 161, and outputs the output signal of the coupler 157. When the level of P is lowered, the first attenuator 171 causes the output signal of the harmonic generator 161 to be attenuated less.

The controller 191 adjusts the degree of attenuation of the first attenuator 171 according to the level of the output signal of the detector 159. In other words, when the level of the output signal of the detector 159 increases, the degree of attenuation of the first attenuator 171 increases. When the level of the output signal of the detector 159 decreases, the degree of attenuation of the first attenuator 171 increases. Less. The control unit 191 also detects the phase of the output signal RF5 of the phase adjusting unit 181 and transmits the phase to the delay unit 141 to control the degree of delay of the delay unit 141. That is, the control unit 191 outputs the output signal RF4 of the delay unit 141 so that the phase of the output signal RF4 of the delay unit 141 is 180 degrees faster than the phase of the output signal RF5 of the phase adjustment unit 181. Controls the degree of delay. Therefore, the phase of the output signal RF5 of the phase adjusting unit 181 and the phase of the output signal RF4 of the delay unit 141 always differ by 180 degrees.

3A to 3H are diagrams illustrating transfer function characteristics and timing pulses of the signals illustrated in FIG. 1. An operation of the modulation depth performance improving circuit 101 shown in FIG. 1 will be described with reference to FIGS. 3A to 3H.

When the RF signal RF1 is input to the signal separator 111, the signal separator 111 splits the RF signal RF1 in half and outputs the first signal RF2 and the second signal RF3. Since the IM signal 221 included in the RF signal RF1 is very small in size, the IM signals included in the first signal RF2 and the second signal RF3 are also very small in size. The first signal RF2 is attenuated while passing through the third attenuator 121 so that the IM signal becomes smaller. The output signal of the third attenuator 121 is amplified by the first amplifier 131 and transmitted to the delay unit 141. The delay unit 141 delays the input signal by a predetermined time and outputs the delayed signal. Since the IM signal 363 is present in the output signal RF4 of the delay unit 141 as shown in FIG. 3E, the transfer function characteristic of the output signal RF4 of the delay unit 141 is shown in FIG. 3D. As shown, it has nonlinearity 321.

The second signal RF3 is attenuated by the second attenuator 153 to a predetermined size and then amplified by the second amplifier 155. At this time, the amplification degree of the IM signal included in the output signal of the second attenuator 153 is much larger than that of the original signal. Therefore, the IM signal included in the signal output from the second amplifier 155 is more than half of the original signal. The output signal of the second amplifier 155 is input to the harmonic generator 161 via the coupler 157. The detector 159 detects the phase and the level of the output signal of the coupler 157 and adjusts the degree of attenuation of the second attenuator 153 according to its magnitude. That is, when the level of the output signal of the coupler 157 increases, the degree of attenuation of the second attenuator 153 increases. When the level of the output signal of the coupler 157 decreases, the degree of attenuation of the second attenuator 153 decreases. Is less. Therefore, the output signal of the coupler 157 is maintained at a constant magnitude.

The harmonic generator 161 amplifies the IM signal included in the output signal of the coupler 157 to bring it closer to the original signal. The output signal of the harmonic generator 161 is attenuated by the first attenuator 171 at a predetermined rate and then transmitted to the phase adjuster 181. The phase adjuster 181 converts the input signal by 180 degrees and transmits the converted signal to the combiner 195. The timing pulse of the output signal RF5 of the phase adjuster 181 is the same as in FIG. 3B, and its transfer function characteristics are shown in FIG. 3A. As described above, the transfer function characteristic of the output signal RF5 of the phase adjusting unit 181 is opposite to the nonlinearity (321 of FIG. 3D) of the transfer function characteristic of the output signal of the delay unit 141 (see FIG. 3A). 311).

The output signal RF4 of the delay unit 141 and the output signal RF5 of the phase adjuster 181 are combined in the combiner 195, and the timing pulse of the RF signal RF6 output from the combiner 195 is As shown in Fig. 3G, there is only an original signal 371 and no IM signal, and its transfer function characteristic has linearity 331 as shown in Fig. 3F.

Since the modulation depth performance improving circuit 101 can be applied to CDMA and W-CDMA, various applications are possible in RF or microwave fields.

3 is a block diagram of an optical transceiver according to the present invention. Referring to FIG. 3, the optical transceiver 401 includes a modulation depth performance improving circuit 101, an optical converter 411, an optical converter driving and monitoring unit 431, an optical signal temperature controller 421, and an RF converter 451. And an RF signal driving and monitoring unit 461, an amplifier 471, and a wavelength division multiplexing coupler 441.

The modulation depth performance enhancement circuit 101 inputs an RF signal RF1 having an original signal 211 in FIG. 2 and an IM signal 221 in FIG. 2, and the IM signal 221 in FIG. 2 is removed and the original signal. The RF signal RF6 having only (Fig. 3G 371) is outputted. Since the modulation depth performance improving circuit 101 is the same as that described with reference to FIG. 1, redundant description is omitted.

The optical converter 411 converts the RF signal RF6 output from the modulation depth performance improving circuit 101 into an optical signal. The light converter 411 includes a laser diode.

The optical signal driving and monitoring unit 431 monitors the optical signal output from the optical converter 411 and controls the size of the optical signal to be constant. That is, the optical signal driving and monitoring unit 431 controls a constant current to flow in the optical transducer 411 so that the optical transducer 411 maintains a constant optical output, and controls the optical signal and the optical transducer 411. The value of the flowing current can be monitored by direct current (DC) voltage.

The optical signal temperature controller 421 controls the optical signal output from the optical converter 411 to be always constant regardless of the temperature change. That is, the optical signal temperature control unit 421 controls the temperature of the light converter 411 so that the light converter 411 can produce an appropriate light output in an environment of any temperature. If there is no optical signal temperature control unit 421, the threshold voltage of the laser diode is changed according to the temperature change, and accordingly the light output of the laser diode is changed and the laser diode is fatally damaged. As a result, the lifetime of the laser diode is shortened. do.

The RF converter 451 receives an optical signal output from the optical converter 411 and converts it into an RF signal. The RF converter 451 has a photodiode. The RF converter 451 receives an optical signal output from the optical converter 411 through optical paths 481 and 482 such as an optical fiber, an optical cable, an optical waveguide, and the like, and in some cases, may be received wirelessly.

The RF signal driving and monitoring unit 461 monitors the RF signal output from the RF converter 451 and controls the size of the RF signal to be constant. That is, the RF signal driving and monitoring unit 461 may drive a constant current to flow through the RF converter 451, and may monitor the optical power input to the RF converter 451 as a DC voltage value.

The amplifier 471 amplifies the RF signal output from the RF converter 451.

The wavelength division multiple coupler 441 divides the optical signal outputted from the optical converter 411 and transmitted through the optical path 481 into a plurality of branch numbers and distributed to the optical path 482 of the output terminal. By providing the wavelength division multiple coupler 441, transmission and reception are possible in one core.

As such, the optical transceiver 401 includes the modulation depth performance enhancement circuit 101 to improve the C / N ratio and improve spurious.

The best embodiments have been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not intended to limit the scope of the present invention as defined in the meaning or the utility model registration claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the attached utility model registration claims.

As described above, according to the present invention, the modulation depth performance improving circuit 101 removes and outputs an IM signal (221 in FIG. 2) included in the input RF signal RF1 in the modulation depth performance improving circuit 101. The transfer function characteristic of the output RF signal RF6 has linearity (331 of FIG. 3F). Thus, the modulation depth of the RF signal having a high frequency band, for example, the 900 [MHz]-2 [GHz] frequency band is improved. Accordingly, the C / N ratio of the optical transceiver 401 having the modulation depth performance improving circuit 101 is improved and the spurious is improved.

In addition, a repeater equipped with a modulation depth performance improving circuit 101 or an E / O (Electric to Optic) -O / E (Optic to Electric) converter is 3 to 7 [dB] than the RF power of a conventional optical transceiver. ] It can be loaded with more accuracy and can eliminate distortion by the 3rd and 5th IM signals, reducing the load on the equipment and manufacturing cost.

Claims (7)

A signal separator for inputting an RF signal having an original signal and an IM signal, separating the first signal into a first signal and a second signal; A first amplifier amplifying the first signal; An automatic gain control unit which constantly controls the gain of the second signal; A harmonic generator for amplifying the magnitude of the IM signal included in the output signal of the automatic gain controller to be close to the original signal; A first attenuator configured to attenuate the output signal of the harmonic generator to a predetermined size; A phase adjuster for converting the output signal of the first attenuator 180 degrees; A delay unit for delaying the output signal of the first amplifying unit so that the phase of the output signal of the first amplifying unit and the phase of the output signal of the phase adjusting unit are 180 degrees apart; And And a combiner for combining the output signal of the delay unit and the output signal of the phase adjuster to output an RF signal from which the IM signal has been removed. The method of claim 1, wherein the automatic gain control unit A second attenuator for attenuating the second signal; A second amplifier for amplifying the IM signal included in the output signal of the second attenuator largely and amplifying the original signal small; A coupler for extracting a part of the output signal of the second amplifier; And And a detection unit for detecting a phase and a level of an output signal of the coupler and feeding it back to the second attenuating unit. The attenuator of claim 2, wherein the detector is coupled to the detector, the first attenuator, the phase adjuster, and the delay unit. And a control unit for controlling the degree of delay of the delay unit according to the phase of the output signal of the phase adjuster such that the phase of the output signal of the delay unit and the output signal of the phase adjuster are 180 degrees apart. Modulation depth performance enhancement circuit. The modulation depth performance improving circuit of claim 1, further comprising a third attenuator configured to attenuate the magnitude of the first signal and transmit the attenuated signal to the first amplifier. A modulation depth performance improving circuit for inputting an RF signal having an original signal and an IM signal, and removing and outputting an IM signal included in the RF signal; An optical converter for converting an RF signal output from the modulation depth performance improving circuit into an optical signal; An optical signal driving and monitoring unit for monitoring an optical signal output from the optical converter and controlling the size of the optical signal to be constant; An optical signal temperature controller for controlling the optical signal to be always constant regardless of temperature change; An RF converter which receives an optical signal output from the optical converter and converts the optical signal into an RF signal; An RF signal driving and monitoring unit for monitoring the RF signal output from the RF converter and controlling the size of the RF signal to be constant; And And an amplifier for amplifying the RF signal output from the RF converter. 6. The modulation depth performance improving circuit as claimed in claim 5, wherein said optical converter is a laser diode. 2. The modulation depth performance improving circuit as recited in claim 1 wherein said RF converter is a photodiode.