JP3250579B2 - Distortion correction circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for correcting a nonlinear distortion contained in an output signal corresponding to an input signal of a nonlinear device.

[0002]

2. Description of the Related Art An analog transmission system can transmit an equal amount of information in a much narrower bandwidth than a digital transmission system such as pulse code modulation (PCM).
In addition, the wired optical transmission system can transmit information in a much wider band than the wired electric transmission system, and the influence of disturbance from the surrounding environment where the transmission medium is installed is much smaller. Therefore, optical analog transmission for transmitting a large amount of information such as a moving image using an optical fiber as a transmission medium has been receiving attention.

In analog transmission, as a result of transmitting a signal carrying information as an analog waveform from a transmitting device to a receiving device, the receiving device faithfully reproduces an analog waveform carrying information intended for transmission by the transmitting device. I need to be able to do it. Therefore, an optical transmission system including a converter for converting an analog electric signal to an analog optical signal (EO converter), a transmission medium for the analog optical signal, and a converter for converting the analog optical signal to an analog electric signal (OE converter) is provided. There is a technical difficulty in analog transmission in that the analog signal carrying information has a transmission characteristic in which nonlinear distortion is suppressed as much as possible and frequency dependence is suppressed as much as possible. For this purpose, for each element of the EO converter, the optical transmission medium, and the OE converter that constitute the optical transmission system, an output signal that has a small non-linear distortion with respect to the intensity of the input signal is required for the optical transmission system. Ideally, it is ideal to realize the generation of an output signal that has no frequency dependence for each frequency component included in the input signal, and development and prototyping are being performed on each of these elements.

[0004] Among the above-mentioned elements, regarding the EO converter, a method of converting into an analog optical signal by direct modulation by an analog electric signal carrying information is the simplest in configuration and is highly feasible. Further, in order to cope with long-distance transmission, it is desirable that the output light of the EO converter has a high intensity. However, the light emitting element L that can be used at present is
The ED or the semiconductor laser element has a non-linear component in the electric-optical conversion characteristic. In particular, when the emission intensity is high, the proportion of the non-linear component is high. Therefore, high-quality optical analog transmission cannot be realized simply by directly modulating the light emitting element with an analog electric signal carrying information. Therefore, before performing the electro-optic conversion in the light emitting element, a distortion opposite to the amount corresponding to the non-linear distortion caused by the electro-optic conversion is applied by performing an electric pre-modulation on the electric signal carrying information. A method is known in which a light emitting element is driven by the pre-modulated electric signal to maintain the linearity between an analog electric signal carrying information and an output optical signal.

As a distortion correction circuit which is a pre-modulation circuit employing this method, there is a circuit disclosed in Japanese Patent Application Laid-Open No. 3-179807. FIG. 9 shows a block configuration of this circuit. In this circuit, an analog electric signal carrying information is input to the directional coupler 910 as an input signal. Directional coupler 91
0 distributes this signal to the first path and the second path. At this time, the power of the signal distributed to the first path is made much larger than the power of the signal distributed to the second path (for example, a distribution ratio of 11 dB). Corresponding to the signal distributed to the second path, a distortion generator 915 generates second-order or higher input frequency intermodulation distortion, and an amplitude adjustment block 917 adjusts the amplitude of the intermodulation distortion signal. Here, the amplitude is adjusted so that the magnitude is equal to the inherent nonlinear distortion of the light emitting element and the sign is opposite. The output signal of the amplitude adjustment block 917 is input to the frequency adjustment block 919, and the amplitude and phase are adjusted so as to match the frequency dependence of the intrinsic distortion of the light emitting element. The output signal of the frequency adjustment block 919 is input to the phase fine adjustment block 921, and the phase is further adjusted. On the other hand, the signal distributed to the first path is simply delayed with the waveform as it is through the phase matching block 923 by an external delay means (for example, a coaxial cable of a predetermined length), and the signal is transmitted to the second path. Phase matching with the passed signal is achieved. The final matching of the phase of the signal passing through the first path and the phase of the signal passing through the second path is achieved by operating the phase fine adjustment block 921. In this way, the signals whose phases match each other are combined by the directional coupler 911,
An electric signal is output to the light emitting element in which the nonlinearity and the frequency dependency of the light emission amount with respect to the driving current amount specific to the light emitting element are compensated. As a result, the light emitting element outputs an optical signal that faithfully reflects the waveform of the analog electric signal carrying the information.

When a large power signal is input to the distortion generator 915 employed in this circuit, a higher-order distortion occurs in addition to the distortion signal intended to be generated by the distortion generator 915. In order to cope with the case of a power signal, most of the power is transmitted with the waveform of the input signal as it is to the first path, and a distribution signal whose power is sufficiently reduced is used to generate distortion in the second path. I'm using

[0007]

Since the conventional distortion correction circuit is constructed as described above, a first path and a distorted waveform signal for transmitting the distributed signal as it is in pre-modulation are generated. Since the circuit configuration of the second path is completely different from that of the second path, the first path is used to match the electrical path length of the first path and the second path when combining the two signals.
However, there is a problem that the delay circuit installed in the path becomes large-scale and it is difficult to reduce the size of the circuit.

[0008]

A distortion correction circuit according to the present invention comprises:
(A) first distribution means for distributing an externally input electric signal into a first signal to a first path and a second signal to a second path; and (b) a first path. The first installed in
A first distortion generating means for applying an odd-order nonlinear distortion relating to the intensity to the signal of (c), and (c) an even-order nonlinear distortion relating to the intensity relative to the second signal, which is provided on the second path. (D) an output signal of the first distortion generator and an output signal of the second distortion generator, the second distortion generator being generated and having the same electrical path length as the first distortion generator. (E) combining the input electric signal with the first electric signal and outputting the electric signal to the outside.
The first multiplexing from the first distribution means with the waveform as it is
It is characterized in that no path is provided for passing through the means . Here, the first distortion generating means includes (1) a second distribution means for distributing the first signal into two signals having mutually inverted waveforms, and (2) an output signal of the second distribution means. A first non-linear attenuator for generating a distortion signal input to one of the
(3) a second nonlinear attenuator having substantially the same circuit configuration as the first nonlinear attenuator and receiving the other of the output signals of the second distribution means; and (4) a first nonlinear attenuator. Second combining means for combining the output signal and the output signal of the second non-linear attenuator by taking a difference between the output signal and the output signal of the second nonlinear attenuator.
A third distribution unit that distributes the second signal into two signals having mutually inverted waveforms, and (2) a third distribution unit that has substantially the same circuit configuration as the first nonlinear attenuator. A third nonlinear attenuator for inputting one of the output signals; and (3) a fourth nonlinear attenuator having substantially the same circuit configuration as the first nonlinear attenuator and receiving the other of the output signals of the third distribution means. A non-linear attenuator,
(4) Third combining means for summing the output signal of the third non-linear attenuator and the output signal of the fourth non-linear attenuator and multiplexing the signals. Further, the first to fourth nonlinear attenuators include (1) a nonlinear element,
(2) Bias means for applying a bias for controlling the operating characteristics of the nonlinear element to the nonlinear element, and (3) an attenuator using a plurality of electric linear passive elements.

Further, another distortion correction circuit according to the present invention comprises:
(A) an electric signal input from the outside to the first path to the first path;
And (b) an odd-order frequency dependence on the intensity of the first signal with respect to the first signal, the fourth signal being distributed to the first signal and the second signal to the second path. (C) compensating for the frequency dependence of the first-order component with respect to the intensity of the output signal of the third distortion generator provided on the first path. A slope compensating means for generating nonlinear distortion having an even-order frequency dependence with respect to the strength of the second signal, which is provided on the second path, and the same as the third distortion generating means; Fourth distortion generating means having an electrical path length; (e) phase matching means disposed on the second path for delaying an output signal of the fourth distortion generating means; and (f) slope compensating means. The sum of the output signal of the phase matching means and the output signal of the A fourth multiplexing means for outputting a signal,
Characterized by the following. Here, the third distortion generating means is a fifth distributing means for distributing the first signal into two signals having mutually inverted waveforms, and a third distributing means for inputting one of the output signals of the fifth distributing means. The fifth nonlinear attenuator has substantially the same circuit configuration as the fifth nonlinear attenuator,
A sixth nonlinear attenuator to which the other of the output signals of the fifth distributing means is input, and a sixth nonlinear attenuator that combines the output signal of the fifth nonlinear attenuator and the output signal of the sixth nonlinear attenuator to combine the signals A fourth distributing means for distributing the second signal into two signals having mutually inverted waveforms, and a fifth nonlinear attenuator. A seventh nonlinear attenuator for inputting one of the output signals of the sixth distributing means, and a circuit constitution substantially the same as that of the fifth nonlinear attenuator; An eighth non-linear attenuator for receiving the other one of the output signals, and a sixth multiplexing means for multiplexing the sum of the output signal of the seventh non-linear attenuator and the output signal of the eighth non-linear attenuator And may be characterized by the following. The fifth to eighth non-linear attenuators may include a non-linear element, a bias unit for applying a bias to control the operating characteristics of the non-linear element to the non-linear element, an attenuator using a plurality of electric linear passive elements, And means for generating frequency-dependent distortion. Here, the means for generating frequency-dependent distortion may be characterized in that it is configured by combining a plurality of electric linear passive elements.

The nonlinear element used in the first to eighth nonlinear attenuators may be one of a diode and a transistor, and the bias means may be a variable voltage source.

[0011]

The distortion correction circuit of the present invention is configured as described above.
First, an analog electric signal carrying information as an input signal is divided into two signals at a predetermined ratio. The distributed first signal is input to a first distortion generation circuit, and is further divided into two signals. The two further distributed signals are input to two nonlinear attenuators having substantially the same circuit configuration, are provided with nonlinear distortion, are output, and are combined by taking the difference between these output signals. As a result of the multiplexing, the waveform is obtained by adding odd-order nonlinear intermodulation distortion to the original signal waveform. Further, the distributed second signal is input to the second distortion generating circuit, and is further distributed to two signals that are mutually inverted. The two further distributed signals are respectively input to two nonlinear attenuators having substantially the same circuit configuration as the two nonlinear attenuators in the first distortion generating circuit, and nonlinear distortion is generated and output. The output signals are summed and multiplexed. As a result of this multiplexing, the waveform becomes the waveform of the even-order nonlinear intermodulation distortion itself.

Since the first distortion generating circuit and the second distortion generating circuit are configured to be substantially symmetrical and to have substantially the same electrical path length for the signal,
Outputs of the first and second distortion generating circuits are subjected to phase matching without using delay means and combined to generate a drive signal with a predetermined distortion.

Further, another distortion correction circuit according to the present invention comprises:
An analog electric signal carrying information as an input signal is divided into two signals at a predetermined ratio. The divided first signal is input to a third distortion generating circuit, and further divided into two signals that are inverted from each other. The two further distributed signals are input to nonlinear attenuators each having substantially the same circuit configuration, are subjected to nonlinear distortion having frequency dependence on the intensity, and are output. The difference between these output signals is calculated. After the wave, the frequency dependency given to the first-order component with respect to the intensity is compensated and output. The waveform of this compensation result is
Non-linear distortion having odd-numbered frequency dependence on the intensity is given to the original signal waveform. Further, the distributed second signal is input to the fourth distortion generating circuit, and is further distributed to two signals that are inverted with respect to each other. The two further distributed signals are input to a nonlinear attenuator having substantially the same circuit configuration as that of the nonlinear attenuator in the third distortion generating circuit, are applied with nonlinear distortion having frequency dependence on intensity, and are output. , Are summed up and multiplexed. As a result of this multiplexing, the waveform becomes a waveform of nonlinear distortion itself having even-order frequency dependence on the intensity.

The third distortion generating circuit and the fourth distortion generating circuit are configured substantially symmetrically, and are configured so that the electrical path lengths for signals are substantially the same.
The outputs of the first path and the second path are subjected to phase matching only by small-scale phase matching means provided in the second path without using a large-scale delay means as in the related art. A drive signal that is waved and given a predetermined distortion is generated.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

(First Embodiment) This embodiment is a distortion correction for outputting a drive signal of a nonlinear element in which a nonlinear distortion due to the strength of the input signal is applied to an analog electric signal carrying information as an input signal. Circuit, and when the input signal strength is X, the output signal strength is -A (X + αX ² + βX ³ + ·
..). FIG. 1 is a configuration diagram of a distortion correction circuit according to the present embodiment, and FIG. 2 is a detailed circuit configuration thereof.

This distortion correction circuit includes: (a) an input signal for a first signal;
A distributor 110 for distributing the first signal to the first path and the second signal to the second path at a predetermined ratio, and (b) inverting the first signal installed in the first path Then, a distortion generator 211 having the same magnitude as the third-order or higher odd-order non-linear intermodulation distortion generated by the non-linear element to be driven and giving the opposite sign to the inverted signal. (C) a distortion having the same magnitude as the second-order or higher even-order non-linear intermodulation distortion generated in the non-linear element to be driven installed in the second path, and generating distortion having the opposite sign. A generator 212;
(D) a multiplexer 310 for multiplexing the output signal of the distortion generator 211 and the output signal of the distortion generator 212 at a predetermined ratio.

The distributor 110 is composed of a wiring and a resistance distributor. A distortion generator 211 is connected to the first path without using an element.
Connected to The second path is connected to the strain generator 212 via a resistance divider. In this embodiment, the resistor divider is configured by connecting a resistor R81 and a resistor R82 in series as shown in FIG. 2, and is about 1/1 of the signal branched to the first path.
The signal having the amplitude of 8 is branched to the second path.

The distortion generator 211 includes a distributor 411 composed of an inverting transformer (T11 in FIG. 2) having the same power and distributing the two signals to each other, and a nonlinear generator for applying nonlinear distortion to one of the signals. A diode (D11 in FIG. 2) as a device and a π-type attenuator (R11, R12, R in FIG. 2)
13) and a group of capacitors for removing the DC component (FIG. 2)
C11, C12, C13)
11 and elements similar to those of the nonlinear attenuator 511 that applies nonlinear distortion to the other signal (D21, R21, R2 in FIG. 2).
2, R23, C21, C22, C23), variable power supplies VB1 and VB2 for supplying a bias voltage for adjusting the operating point of each diode,
Output signal of nonlinear attenuator 511 and nonlinear attenuator 512
And a multiplexer 611 composed of an inverting transformer (T12 in FIG. 2), which multiplexes the signals by taking the difference from the output signal of T.sub.x and takes out only the odd-order components.

The distortion generator 212 includes a distributor 412 composed of an inverting transformer (T21 in FIG. 2) for distributing two signals having the same power and inverted to each other, and a nonlinear generator for applying nonlinear distortion to one of the signals. The nonlinear attenuator 513 (D31, R31, R3 in FIG. 2) configured similarly to the attenuator 511
2, R33) and a group of capacitors (C31, C32, C33 in FIG. 2) for removing the DC component, and the same elements as the nonlinear attenuator 511 for applying the nonlinear distortion to the other signal. (D41, R41 in FIG. 2,
R42, R43, C41, C42, C43), and variable power supplies VB3 and VB4 for supplying a bias voltage for adjusting the operating point of each diode.
And the output signal of the nonlinear attenuator 513 and the nonlinear attenuator 5
And a multiplexer 612 composed of a wiring and an inverting transformer (T22 in FIG. 2), which multiplexes the signals by taking the sum of the output signals of the fourteen signals and multiplexes them, and takes out and inverts only the components of the even or higher order. Is done.

The multiplexer 310 is composed of a wiring and a resistor group. The signal from the first path does not pass through the element, the signal from the second path passes through the resistance divider, and then the two are combined. It is waving. In this embodiment, as shown in FIG. 2, the resistor divider is formed by connecting a resistor R91 and a resistor R92 in series.
After the amplitude of the signal input from the first path is reduced to about ８, the signal and the signal input from the first path are summed and multiplexed.

Since the nonlinear attenuators 511 to 514 are constructed by connecting a diode and an attenuator in parallel as shown in FIG. 2, even if a large power signal is input, the generation of unintended distortion components occurs. Can be suppressed. Further, each element of the signal transmission line is selected with a constant so that the impedance is matched, and is set to 75Ω in the circuit of the present embodiment.

An analog electric signal carrying information input to the distortion correction circuit is distributed by a distributor 110 into a signal to a first path and a signal to a second path. The signal branched to the first path is first distributed by the distributor 411 into two signals having the same power and inverted from each other. Each signal is supplied with a bias voltage (VB1 and VB1) so as to have similar operating characteristics set for each signal.
2) is input to the set non-linear attenuator 511 and non-linear attenuator 512, to which a non-linear distortion is applied and output. Therefore, in the two signals output from the nonlinear attenuator 511 and the nonlinear attenuator 512, odd-order components have opposite signs and the same magnitude, and even-order components have the same sign and magnitude. are doing. These signals are combined by taking a difference in the combiner 611 to obtain an odd-order component (−A
(X + βX ³ +)) only. Here, coefficient β is adjusted by bias voltages (VB1 and VB2) applied to nonlinear attenuator 511 and nonlinear attenuator 512.

The signal branched to the second path is first distributed by the distributor 412 into two inverted signals having the same power. Each signal has a nonlinear attenuator 51 in which bias voltages (VB3 and VB4) are set so as to have similar operating characteristics set for each signal.
3 and a non-linear attenuator 514 to which a non-linear distortion is applied and output. Therefore, in the two signals output from the nonlinear attenuator 513 and the nonlinear attenuator 514, odd-order components have opposite signs and the same magnitude, and even-order components have the same sign and magnitude. are doing. These signals are summed by a multiplexer 612 and combined to extract only the even-order component (α′X ² +...). Here, the coefficient α is determined by the nonlinear attenuator 513 and the nonlinear attenuator 5.
Bias voltage (VB3 and VB4) applied to 14
It is adjusted by.

The generated signal having two nonlinear distortions is multiplexed by the multiplexer 310 to suppress the nonlinear intermodulation distortion of the nonlinear element to be driven.
(X + αX ² + βX ³ +...)).

In this embodiment, a nonlinear attenuator is used as shown in FIG.
Although the diode of FIG. 3A and the π-type attenuator are combined, the transistor of FIG. 3B and the T-type attenuator, or the diode and T-type attenuator of FIG. Good.

(Second Embodiment) In this embodiment, a distortion correction for outputting a drive signal of a nonlinear element in which a nonlinear distortion due to the strength of the input signal is applied to an analog electric signal carrying information as an input signal. Circuit, and when the input signal strength is X, the output signal strength is -A (X-αX ² + βX ^3- ·
..). FIG. 4 is a block configuration diagram of a distortion correction circuit according to the present embodiment, and FIG. 5 is a detailed circuit configuration thereof. This distortion correction circuit has substantially the same configuration as the distortion correction circuit of the first embodiment, and differs only in the configurations of the distributor and the multiplexer of the even-order distortion generator.

That is, the distortion correction circuit of the present embodiment
(A) A distributor 110 that distributes an input signal to a first signal to a first path and a second signal to a second path at a predetermined ratio.
And (b) after inverting the first signal provided in the first path, the inverted signal is the same as the third-order or higher odd-order nonlinear intermodulation distortion generated by the nonlinear element to be driven. Distortion generator 21 having a magnitude of
1 and (c) generate distortion having the same magnitude as the second-order or higher even-order non-linear intermodulation distortion generated by the non-linear element to be driven installed in the second path and having the opposite sign. And a multiplexer 310 for (d) multiplexing the output signal of the distortion generator 211 and the output signal of the distortion generator 222 at a predetermined ratio.

The distributor 110, the distortion generator 211 and the multiplexer 310 have the same configuration as in the first embodiment.

The distortion generator 222 includes a first inverting transformer (T21 in FIG. 5) and a second inverting transformer (T2 in FIG. 5) for distributing two signals having the same power and mutually inverted.
5), and the same nonlinear attenuator 513 as in the first embodiment for applying nonlinear distortion to one of the signals.
A non-linear attenuator 514 for applying the nonlinear distortion to the other signal, and variable power supplies VB3 and VB4 for supplying a bias voltage for adjusting the operating point of each diode, as in the first embodiment. And a multiplexer 622 which is a wiring and takes out the sum of the output signal of the non-linear attenuator 513 and the output signal of the non-linear attenuator 514 and extracts only the even-order components of the second or higher order. You. here,
The second inverting transformer of the distributor 422 is provided to match the electrical path length with the first path.

The analog electric signal carrying the information input to the distortion correction circuit is converted into a signal to the first path and a signal to the second path by the distributor 110 as in the circuit of the first embodiment. The splitter 411, the non-linear attenuator 511, the non-linear attenuator 512,
And the multiplexer 611, the odd-order component (−A (X
+ ΒX ³ +))).

The signal branched to the second path is first distributed by the distributor 422 to two signals having the same power and inverted from each other. Each signal has a nonlinear attenuator 51 in which bias voltages (VB3 and VB4) are set so as to have similar operating characteristics set for each signal.
3 and a non-linear attenuator 514 to which a non-linear distortion is applied and output. Therefore, in the two signals output from the nonlinear attenuator 513 and the nonlinear attenuator 514, odd-order components have opposite signs and the same magnitude, and even-order components have the same sign and magnitude. are doing. These signals are summed by a multiplexer 612 and multiplexed to extract only the even-order component (−α′X ² ...). Here, the coefficient α ′ is determined by the bias voltages (VB3 and VB3) applied to the nonlinear attenuators 513 and 514.
Adjusted in 4).

In the same manner as in the first embodiment, the generated signal having two nonlinear distortions is multiplexed by the multiplexer 310 to suppress the nonlinear intermodulation distortion of the nonlinear element to be driven. The signal (−A (X−αX ² + βX ³ − ·
・)).

In this embodiment, as in the first embodiment,
The nonlinear attenuator is configured by combining the diode of FIG. 3A and the π-type attenuator, but the transistor and the T-type attenuator of FIG. 3B or the diode and the T-type attenuator of FIG. , May be used.

(Third Embodiment) In this embodiment, similarly to the first embodiment, a non-linear element in which a non-linear distortion due to the intensity of the input signal is applied to an analog electric signal carrying information as an input signal. Is a distortion correction circuit that outputs the drive signal of
When the input signal strength is X, the output signal strength is -A (X
+ ΓX ² + βX ³ +...), But the even-order nonlinear distortion, especially the second-order nonlinear distortion, must be so large that it cannot be generated by adjusting the bias voltage in the first embodiment. It is an example of a circuit configuration in the case. FIG.
FIG. 3 is a configuration diagram of a distortion correction circuit according to the present embodiment.

This circuit configuration is different from the circuit of the first embodiment in that a low-distortion amplifier 731 having a multiplication factor of 1 is arranged after the multiplexer of the odd-order distortion generator. 561, and a second distortion generator 562 in which a low distortion amplifier 732 having a predetermined multiplication factor is arranged at a stage preceding the distributor of the even-order distortion generator. Here, the low distortion amplifier 731 is installed in order to match the electrical path length of the first path with the electrical path length of the second path.

The analog electric signal carrying the information input to the distortion correction circuit is converted into a signal to the first path and a signal to the second path by the distributor 110 as in the circuit of the first embodiment. The splitter 411, the non-linear attenuator 511, the non-linear attenuator 512,
And the multiplexer 611, the odd-order component (−A (X
+ ΒX ³ +))). The output signal of the multiplexer 611 is input to the low distortion amplifier 731, and is output with the phase changed without changing the waveform.

The signal branched to the second path is first amplified at a predetermined amplification factor by the low distortion amplifier 732, and is further distributed by the distributor 412 into two inverted signals having the same power. . Each signal has a nonlinear attenuator 5 in which bias voltages (VB3 and VB4) are set so as to have similar operating characteristics set for each signal.
13 and a non-linear attenuator 514 to which a non-linear distortion is applied and output. These signals are summed by a multiplexer 612 and multiplexed to form an even-order component (α ″ X ² +
・ ・) Here, the coefficient α ″ is the amplification factor of the low distortion amplifier 732 times the coefficient α ′ of the first embodiment.

In the same manner as in the first embodiment, the generated signal having two nonlinear distortions is multiplexed by the multiplexer 310 to suppress the nonlinear intermodulation distortion of the nonlinear element to be driven. Signal (-A (X + γX ² + βX ³ + ·
・)).

In this embodiment, the low-distortion amplifier 731 of the first path is installed after the multiplexer 611, but may be installed before the distributor 411. Further, although the low distortion amplifier 732 of the second path is installed before the distributor 412, it may be installed after the multiplexer 611. Also, by adjusting the distribution ratio of the distributor 110 and the amplification factor of the even-order distortion waveform at the time of multiplexing in the multiplexer 310, the mixing ratio of the signal on the first path and the signal on the second path is adjusted. For example, an output drive signal having a relatively large mixing ratio of even-order distortion components can be obtained without using a low distortion amplifier.

(Fourth Embodiment) In this embodiment, a distortion correction for outputting a drive signal of a nonlinear element in which a nonlinear distortion due to the strength of the input signal is applied to an analog electric signal carrying information as an input signal. And the output signal strength is -A (X + α (ω) X ² + β, where X is the input signal strength.
(Ω) X ³ +...). FIG.
FIG. 2 is a configuration diagram of a distortion correction circuit according to the present embodiment. FIG.
FIG. 8A is a circuit diagram of a non-linear attenuator used in the circuit of this embodiment. FIG.
FIG. 8 shows an example in which a combination with a CR resonator is used.
(B) shows an example in which a transistor, a T-type attenuator, and an LCR resonator are combined. Hereinafter, a case where the circuit of FIG. 8A is adopted will be described.

This distortion correction circuit comprises:
A distributor 110 that distributes the first signal to the first path and the second signal to the second path at a predetermined ratio, and (b) the first signal installed in the first path, which is inverted. The distortion having the same magnitude as the nonlinear intermodulation distortion having the third-order or higher odd-order frequency dependence generated by the nonlinear element to be driven, and giving the opposite sign to the inverted signal. Generator 27
1 and (c) the strain generator 271 installed in the first path.
And a slope compensator 751 for compensating for the frequency dependence of the primary component of the input signal, and (d) a non-linear element 2 which is installed in the second path and is driven by the nonlinear element to be driven. A distortion generator 272 having the same magnitude as the non-linear intermodulation distortion having an even-order or higher frequency dependence and generating a distortion having the opposite sign, and (e) installed in the second path. A phase matcher 752 that receives an output signal of the distortion generator 272 and compensates for a phase mismatch by the slope compensator 751 on the first path, and (f) an output signal of the slope compensator 751 and the phase matcher 752 And a multiplexer 310 for multiplexing the output signals at a predetermined ratio.

The distributor 110 and the multiplexer 310 have the same configuration as in the first embodiment.

The distortion generator 271 includes a distributor 411 composed of an inverting transformer for distributing two signals having the same power and inverted to each other, a diode as a nonlinear element for applying nonlinear distortion to one of the signals, a nonlinear attenuator 571 composed of a π-type attenuator, a capacitor group for removing a DC component, and a resonator composed of an electric linear passive element group for generating a frequency-dependent nonlinear distortion; A nonlinear attenuator 572 composed of the same elements as the applied nonlinear attenuator 571, and variable power supplies VB1 and VB for supplying a bias voltage for adjusting the operating point of each diode.
2 and a combiner 611 composed of an inverting transformer for combining the difference between the output signal of the nonlinear attenuator 571 and the output signal of the nonlinear attenuator 572 to extract only odd-order components.
And

The distortion generator 272 has the same power as that of a distributor 412 composed of an inverting transformer for distributing two signals inverted with respect to each other, and a nonlinear attenuator 571 for applying nonlinear distortion to one signal. The nonlinear attenuator 573 composed of a nonlinear attenuator, a capacitor group for removing a DC component, and a resonator composed of an electric linear passive element group for generating a frequency-dependent nonlinear distortion, and the other signal Non-linear attenuator 574 composed of the same elements as non-linear attenuator 571 that applies non-linear distortion; variable power supplies VB3 and VB4 for supplying a bias voltage for adjusting the operating point of each diode; A multiplexing composed of a wiring and an inverting transformer, taking the sum of the output signal of the attenuator 574 and multiplexing, taking out only the second-order and even-order components and performing inversion. And 612, consists of.

The analog electric signal carrying the information input to the distortion correction circuit is distributed by the distributor 110 into a signal to the first path and a signal to the second path. The signal branched to the first path is first distributed by the distributor 411 into two signals having the same power and inverted from each other. Each signal is supplied with a bias voltage (VB1 and VB1) so as to have similar operating characteristics set for each signal.
2) is set, and is input to the non-linear attenuator 571 and the non-linear attenuator 572 for applying the nonlinear distortion having frequency dependency, and the nonlinear attenuator 571 is applied and output. In the two signals output from the nonlinear attenuator 571 and the nonlinear attenuator 572, odd-order components have opposite signs and the same magnitude, and even-order components have the same sign and magnitude. I have. These signals are combined by taking a difference in a combiner 611 and then passed through a slope compensator 751 to obtain an odd-order component (−) to which a nonlinear distortion having frequency dependence is added.
A (X + βX ³ + ··)) is taken out. Where the coefficient β
Is adjusted by bias voltages (VB1 and VB2) applied to the nonlinear attenuator 571 and the nonlinear attenuator 572, and the frequency dependence is adjusted by the value of the variable capacitor.

The signal branched to the second path is first distributed by the distributor 412 into two signals having the same power and inverted from each other. The bias voltage (VB3 and VB4) is set for each signal so as to have the same operating characteristics set for each signal, and the nonlinear attenuator 57 that applies nonlinear distortion having frequency dependence.
3 and a non-linear attenuator 574 to which non-linear distortion is applied and output. Nonlinear attenuator 573 and nonlinear attenuator 5
In the two signals output from 74, odd-order components have the same magnitude with opposite signs, and even-order components have the same sign and magnitude. These signals are combined into a multiplexer 6
After summing at 12 and multiplexing, via the phase matching unit 752,
Only the even-order components (α′X ² +...) Are extracted. Here, the coefficient α is determined by the nonlinear attenuator 573 and the nonlinear attenuator 5.
Bias voltage applied to 74 (VB3 and VB4)
And the frequency dependence is adjusted by the value of the variable capacitor.

The signal having two nonlinear distortions generated in this way is multiplexed by the multiplexer 310 to suppress the nonlinear intermodulation distortion of the nonlinear element to be driven.
(X + αX ² + βX ³ +...)).

In this embodiment, the non-linear attenuator is the one shown in FIG.
Although the diode, the π-type attenuator, and the LCR resonator are combined as shown in (a), the transistor, the T-type attenuator, and the LCR resonator in FIG. 8B may be combined. Alternatively, only one LCR resonator may be provided in the distortion generator and shared by two nonlinear attenuators.

Also, in the present embodiment, modifications are made to the first embodiment in the same manner as in the second and third embodiments.
It is possible to change the sign of the second-order nonlinear distortion or to increase the relative mixing ratio of the even-order nonlinear distortion.

[0051]

As described above in detail, according to the distortion correction circuit of the present invention, an analog electric signal carrying information as an input signal is distributed to two paths, and one path has a waveform of the input signal. A predetermined third-order or more odd-order distortion is applied, and two signals are combined after the second-order or more even-order distortion is generated in the other path. The length can be almost the same, without using a delay circuit,
It is possible to generate an analog electric signal for driving the nonlinear element to which the distortion according to the characteristics of the subsequent nonlinear element is applied. As a result, the waveform of the output signal of the non-linear element to be driven can be accurately converted into a linear signal with respect to the analog electric signal carrying information.

According to another distortion correction circuit of the present invention,
An analog electric signal carrying information as an input signal is distributed to two paths, and one path is provided with a nonlinear distortion having a predetermined third-order or higher odd-order frequency dependency on the waveform of the input signal, and the other is provided with the other. Since the two signals are combined after the nonlinear distortion having the second-order or higher even-order frequency dependency is generated in the path, the electrical path lengths of the respective paths can be substantially the same. It is possible to generate an analog electric signal for driving a nonlinear element provided with a distortion according to the characteristics of a subsequent nonlinear element without using a large-scale delay circuit. As a result, the waveform of the output signal of the non-linear element to be driven can be converted into a linear signal with higher accuracy than an analog electric signal carrying information.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a distortion correction circuit according to a first embodiment of the present invention.

FIG. 2 is a detailed configuration diagram of a distortion correction circuit according to the first example of the present invention.

FIG. 3 is a circuit configuration diagram of a nonlinear attenuator.

FIG. 4 is a configuration diagram of a distortion correction circuit according to a second embodiment of the present invention.

FIG. 5 is a detailed configuration diagram of a distortion correction circuit according to a second example of the present invention.

FIG. 6 is a configuration diagram of a distortion correction circuit according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of a distortion correction circuit according to a fourth embodiment of the present invention.

FIG. 8 is a circuit configuration diagram of a nonlinear attenuator.

FIG. 9 is a block diagram of a conventional distortion correction circuit.

[Explanation of symbols]

110: distributor, 211, 212, 222, 261,
62, 271, 272: distortion generator, 310: multiplexer, 4
11, 412, 422 ... distributors, 511, 512, 51
3,514,571,572,573,574 ... non-linear attenuator, 611,612,622 ... combiner, 731,7
32: Low distortion amplifier, 751: Slope compensator, 752 ...
Phase matching circuit, 910, 911 ... directional coupler, 915
.., Distortion generator, 917, amplitude adjustment block, 919, frequency adjustment block, 921, phase fine adjustment block, 923
... Phase matching block.

Claims (10)

(57) [Claims] A first distribution unit configured to distribute an input electric signal input from the outside into a first signal to a first path and a second signal to a second path; and the first path. A first distortion generating means for applying an odd-order non-linear distortion with respect to the intensity to the first signal; and an intensity for the second signal disposed on the second path. A second distortion generator having the same electrical path length as that of the first distortion generator, and an output signal of the first distortion generator and the second distortion generator. taking the sum multiplexes the output signal of the distortion generating means is composed of a first multiplexing means for outputting an electric signal to the outside, said first distributing said input electrical signal as it waveform hand
A path for passing from the step to the first multiplexing means is provided.
Distortion correction circuit characterized by not having. 2. The signal processing apparatus according to claim 1, wherein the first distortion generating unit distributes the first signal into two signals having inverted waveforms, and one of an output signal of the second distribution unit. And a first non-linear attenuator for generating a distortion signal; and a second non-linear attenuator having substantially the same circuit configuration as the first non-linear attenuator and receiving the other of the output signals of the second distribution means. And a second multiplexing means for multiplexing by taking a difference between an output signal of the first nonlinear attenuator and an output signal of the second nonlinear attenuator; The distortion generating means has a third distribution means for distributing the second signal into two signals having mutually inverted waveforms, and has substantially the same circuit configuration as the first nonlinear attenuator. A third nonlinear attenuator that receives one of the output signals of the third distributing means; A fourth nonlinear attenuator that has substantially the same circuit configuration as that of the third nonlinear attenuator, and that receives the other one of the output signals of the third distribution unit; and an output signal of the third nonlinear attenuator and the fourth nonlinear attenuator. 3. A distortion correction circuit according to claim 1, further comprising: third multiplexing means for multiplexing the signal by taking the sum of the output signal of the filter and the signal. 3. The non-linear attenuator according to claim 1, wherein the first to fourth non-linear attenuators use a plurality of non-linear elements, a bias unit for applying a bias to control the operating characteristics of the non-linear elements to the non-linear elements, and a plurality of electrically linear passive elements. The distortion correction circuit according to claim 2, wherein the distortion correction circuit comprises: 4. A fourth distribution means for distributing an electric signal input from the outside into a first signal to a first path and a second signal to a second path; Third distortion generating means for providing non-linear distortion having odd-order frequency dependence on intensity to the first signal, the third distortion being disposed on the first path; A slope compensating means for compensating for the frequency dependence of the first-order component with respect to the intensity of the output signal of the generating means; and an even-order frequency dependence with respect to the strength for the second signal, which is provided in the second path. A fourth distortion generating means having the same electrical path length as the third distortion generating means, and a fourth distortion generating means disposed on the second path. Phase matching means for delaying the output signal of Distortion correcting circuit for outputting signals to and multiplexes taking the sum of the output signal of the phase-matching means, characterized in that it is composed of a fourth combining means for outputting an electric signal to the outside. 5. The fifth distortion generating means, wherein the third distortion generating means distributes the first signal into two signals having mutually inverted waveforms, and the output signal of the fifth distributing means. A fifth nonlinear attenuator for inputting one of the signals, a sixth nonlinear attenuator having substantially the same circuit configuration as the fifth nonlinear attenuator, and receiving the other of the output signals of the fifth distribution unit; Fifth combining means for combining the output signal of the fifth nonlinear attenuator and the output signal of the sixth nonlinear attenuator, and combining the signals. The fourth distortion generating means A sixth distributing means for distributing the second signal into two signals having mutually inverted waveforms; and a sixth distributing means having substantially the same circuit configuration as the fifth nonlinear attenuator. A seventh nonlinear attenuator that receives one of the output signals of An eighth nonlinear attenuator having substantially the same circuit configuration and receiving the other of the output signals of the sixth distributor, an output signal of the seventh nonlinear attenuator, and an output signal of the eighth nonlinear attenuator 6. A distortion correcting circuit according to claim 4, comprising: a sixth multiplexing means for multiplexing by taking the sum of 6. The fifth to eighth non-linear attenuators use a plurality of non-linear elements, bias means for applying a bias to the non-linear elements for controlling operating characteristics of the non-linear elements, and a plurality of electrically linear passive elements. 6. The distortion correction circuit according to claim 5, further comprising: an attenuator configured to generate frequency-dependent distortion. 7. The distortion correction circuit according to claim 6, wherein said means for generating frequency-dependent distortion is configured by combining a plurality of electric linear passive elements. 8. The distortion correction circuit according to claim 3, wherein the non-linear element is one of a diode and a transistor, and the bias unit is a variable voltage source. 9. The apparatus according to claim 1, wherein the second or fourth distortion generating means includes
2. The following nonlinear distortion amount is positive.
Or a distortion correction circuit according to claim 4. 10. The second or fourth distortion generating means comprises:
2. The following nonlinear distortion amount is negative.
Or a distortion correction circuit according to claim 4.