KR100367825B1 - A balance type Predistorter - Google Patents

Abstract

The present invention relates to a balanced predistorter.

The present invention provides a predistorter for improving the efficiency of a high output amplifier, comprising: a signal distribution unit for distributing an input signal into two signals having a 90 ° phase difference; Signal processors 1 and 2 of the same structure for processing the divided signals; A temperature compensator for adjusting the signal processor 1 and 2 to automatically compensate for a change in temperature to maintain a constant operating characteristic; And a signal synthesizing unit for mixing and distributing the signals processed by the signal processing units 1 and 2 and outputting the divided signals to the high output amplifier.

Balanced predistorter can reduce the cost by using fewer parts in the circuit construction, and can be used in a wide range of signal strengths to fine-tune the intensity of the input signal. It is configured in such a way that if one signal processor does not operate, it can perform a function normally.

Description

Balanced Predistorter {A balance type Predistorter}

The present invention relates to a balanced type predistorter, and in particular, a signal processing unit may be configured in a pair of balanced forms having the same structure to improve the degree of distortion and to be used in a wide range of signal strengths, and to configure a separate temperature compensation circuit. The present invention relates to a balanced predistorter capable of automatically maintaining a constant operating characteristic by responding to a change in current caused by a change in impedance by automatically compensating for a change in temperature.

In general, the conventional series diode predistorter operates very sensitively according to the strength of an input signal, operates only in a narrow input signal range, and has a problem in that matching is broken due to an impedance of an input / output terminal. In addition, a predistorter using a phase shifter and a delay line has many variables to change such as a phase shifter, a regulator, and a delay line in order to match a phase, so that the size of the distortion is large, the price is high, and the phase or gain is adjusted. There was a difficulty.

Accordingly, the present invention has been made to solve the above problems, by configuring a signal processing unit in the form of a pair of the balance structure of the same structure to improve the degree of distortion and can be used in a wide range of signal strength, separate temperature compensation The purpose of the present invention is to provide a balanced predistorter capable of automatically maintaining a constant operating characteristic by responding to a change in current due to a change in impedance by automatically compensating for a change in temperature by configuring a circuit.

1A is a conceptual diagram of a conventional series diode predistorter,

FIG. 1B is a schematic diagram of a diode partial equivalent circuit of FIG. 1A;

Figure 1c is a table of operating characteristics of the series diode predistorter,

2a is a conceptual diagram of a predistorter using a conventional phase shifter and a delay line;

Figure 2b is a conceptual diagram of the predistorter operation of Figure 2a,

3a is a conceptual diagram of a balanced predistorter according to the present invention;

3B is a circuit diagram illustrating the signal processor of FIG. 3A;

3C is a circuit diagram of the temperature compensator of FIG. 3A;

Figure 4 is an embodiment using a conventional series diode predistorter,

4a to 4e is a result table according to an embodiment of FIG.

5 is an embodiment using one path of the balanced predistorter according to the present invention;

5a to 5e is a result table according to an embodiment of FIG.

Figure 6 is an embodiment using a balanced predistorter according to the present invention,

6a to 6e is a result table according to one embodiment of FIG.

* Description of the main symbols in the drawings

30: signal distribution unit 40: temperature compensation unit

50: signal processor 1 60: signal processor 2

70: signal synthesis unit

In order to achieve the above object, a balanced predistorter for improving the efficiency of a high output amplifier according to the present invention, the signal distribution unit for distributing the input signal into two signals having a 90 ° phase difference; First and second decoupling capacitors that prevent or reduce feedback and block the flow of DC voltage components, generating a third-order signal from the input signal and extending the range of the input signal to operate but in series The signal portion including first and second Schottky diodes, a capacitor for adjusting the capacitance value of the Schottky diode, and first and second inductors separating the combination circuit of the Schottky diode and the capacitor from power and ground; Signal processing units 1 and 2 of the same structure for predistorting each signal distributed from the distribution; A temperature compensator for maintaining a constant operating characteristic according to a temperature change of the signal processors 1 and 2, including an amplifier for amplifying a signal and a thermistor whose resistance decreases when the temperature rises; And a signal synthesizing unit for mixing and distributing the signals processed by the signal processing units 1 and 2 and outputting the divided signals to a high output amplifier.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1A is a conceptual diagram of a conventional series diode predistorter, wherein capacitors C1 (11) and C2 (16) are DC decoupling capacitors, and D1 (13) is a Schottky diode for generating a third order signal from an input signal. CP 14 is a capacitor that complements the capacitance value of D 1 13, inductors L 1 12 and L 2 15 pass a direct current and are driven by diode D 1 13 and capacitor C 2 16 from a power source and ground. An inductor that separates a combination circuit so that it is not affected by impedance. This predistorter uses the principle that the dynamic impedance of the diode varies nonlinearly according to the voltage level applied to the Schottky diode D1 (13). The same equivalent circuit can be shown. In addition, the operating characteristics shown in the combination circuit of the diode D1 13 and the capacitor C2 16 can be shown as shown in FIG. 1C. That is, it shows the operating characteristics of the series diode predistorter. By using the diode D1 (13), it can be seen that the positive amplitude and the negative phase deviation are made. However, the circuit as shown in Fig. 1a configuration is diode sensitively operates according to D1 (13) of the input signal strength and the DC tuning voltage that is, V _T is applied to, and also the operation only within a narrow input signal range, and the impedance of the diode As the impedance changes, the impedance of the input / output terminal changes, so that the matching collapse occurs.

FIG. 2A is a schematic diagram of a predistorter using a conventional phase shifter and a delay line. A 3dB coupler 21 for dividing an input signal into two signals, 0 ° and 90 °, and an adjuster for adjusting the signal size (Attenuator 23) A phase shifter 24 that adds a phase delay to the passing signal, a delay line 25 that delays the phase of the pass signal using a pattern or cable, and a pair of Schottky diodes that generate a third order signal. (Shottky Diode: 26, 27), 3dB coupler 28 for mixing and inputting the signal of the separated 0 °, 90 ° phase difference, single signal and output, and resistors (22, 29). The predistorter generates and outputs a third-order signal through forced predistortion using nonlinearities of the Schottky diodes 26 and 27. That is, third-order signal distortion is generated through a signal path using the regulator 23, the phase shifter 24, and the diodes 26 and 27, and a circular path is formed through the path formed by the delay line 25. Passed through the linear portion of the input signal is coupled through the coupler 28, which is a signal coupling portion. However, in the circuit configuration as shown in FIG. 2A, there are too many variables to be changed in order to match the signal phase and gain such as the adjuster 23, the phase shifter 24, and the delay line 25. There is a difficulty, and there is a problem that the price rises. FIG. 2B illustrates a conceptual diagram of the predistorter operation of FIG. 2A. In the conventional predistorter described above, a power amplifier is connected to a circuit end, and the predistorter stage is adjusted to compensate for the nonlinearity of the power amplifier.

3A is a conceptual diagram illustrating a balanced predistorter according to the present invention, a signal distribution unit 30 for distributing an input signal and a pair of signal processing units 1 and 2 (50, 60) having the same structure for processing the distributed signal. ), A temperature compensator 40 capable of automatically controlling a temperature change of the signal processor 1 and 2 to maintain a constant operating characteristic, and mixing and distributing the signals processed by the signal processor 1 and 2 to a high output amplifier. It consists of a signal synthesizing unit 70 for outputting. That is, by constructing and using a pair of signal processing units, the degree of predistortion can be improved. That is, the signal distribution unit 30 and the signal synthesizing unit 70 are used to prevent the impedance matching of the input / output terminal from collapsing according to the magnitude of the input signal, which is a problem of the conventional predistortion of FIG. 1A. FIG. 3b is a circuit diagram of the signal processor of FIG. 3a, which extends the range of an input signal operating by connecting and using a conventional Schottky diode in series as diodes D1 33 and D2 34. Signal processor 1 And by using the balance as shown in the 2 can be produced the effect of improving the predistortion degree to 3dB ~ 5dB. At this time, the capacitor CP 35 is to adjust the capacitance values of the Schottky diodes D1 33 and D2 34. That is, it is used when the capacitance values of the Schottky diodes D1 33 and D2 34 preset at the time of manufacture are changed as necessary. In addition, the improved performance can be improved inexpensively without configuring complicated adjustment functions such as the conventional phase shifter and the predistorter using the delay line. To explain the process of the balanced predistorter, the input signal is separated into two signals having a phase difference of 0 ° and 90 ° in the signal distribution unit 30. The separated signal strength is reduced by half. Pre-distortion of the input signals is performed through a pair of balanced predistorters, that is, two serial diode predistortion circuits having the same structure divided into the signal processor 1 (50) and the signal processor 2 (60). At this time, the temperature compensation unit 40 automatically compensates to maintain a constant operating characteristic even if the temperature changes in the signal processing units 1 and 2 (50, 60). The signal synthesizing unit 70 receives and mixes the signals processed by the signal processing units 1 and 2 (50, 60). At this time, the phase difference between the two signals is 0 °, and the magnitude of the signal is the signal distribution unit 30. The size of the signal is equal to the size of the input signal, but the amount of predistortion is increased by about 3dB than using one path.

FIG. 3C illustrates the circuit diagram of the temperature compensator of FIG. 3A. The amplifier 43 amplifies the signal, thermistor 44 decreases in resistance when the temperature rises, and the amplification degree of the amplifier 43. It consists of resistors 41, 42, 45 for adjustment. The temperature compensation circuit automatically compensates the DC tuning voltage V _T applied to the Schottky diodes 33 and 34 of FIG. 7 according to the temperature, thereby responding to a change in current due to a change in the dynamic impedance of the diodes due to heat. . Thus, the signal processing units 1 and 2 (50, 60) can maintain a constant operating characteristic at all times regardless of the temperature change.

4 is an embodiment using a conventional series diode predistorter, and FIGS. 4A to 4E show a result table according to the embodiment of FIG. 4. That is, Figure 4a is a table showing the degree of improvement of the third term, the linearity is improved only at a specific power level (-16dBm ~ -6dBm), Figure 4b is a table showing the degree of attenuation of the signal passing through the predistorter, about 2dB Shows signal attenuation. And 4c is a table showing the size difference between the first term and the third term, the wider the interval, the better, Figure 4d is a table showing the degree of improvement of the P ₁ dB compression point, Figure 4e is the degree of the third term changes in the spectrum This table shows:

FIG. 5 is an embodiment using one path of the balanced predistorter according to the present invention, and FIGS. 5A to 5E show a result table according to the embodiment of FIG. 5. That is, Figure 5a is a table showing the degree of improvement of the third term, which shows that the linearity is improved at the entire power level, the larger the interval indicates that the improvement is much. Figure 5b is a table showing the degree of attenuation of the signal passing through the predistorter, showing that there is a signal attenuation of about -2dB. 5c is a table showing the difference between the first term and the third term, the wider the interval, the better. FIG. 5d is a table showing the degree of improvement of the P ₁ dB compression point, and FIG. 5e shows the degree of change of the third term in the spectrum. The table shows.

6 is an embodiment using a balanced predistorter according to the present invention, and FIGS. 6A to 6E show a result table according to the embodiment of FIG. 6. That is, Figure 6a is a table showing the degree of improvement of the third order, the linearity is improved than the One Path type at the entire power level, Figure 6b is a table showing the degree of attenuation of the signal passing through the predistorter, compared to the One Path type The loss is markedly reduced. 6c is a table showing the size difference between the first term and the third term, the wider the interval is, the better, and FIG. 6d is a table showing the degree of improvement of the P ₁ dB compression point. It shows improvement over Path type. 6E is a table showing the degree of change of the third term on the spectrum.

As described above, the balanced predistorter can reduce the cost by using fewer components in the circuit configuration, and can be used in a wide range of signal strengths, so that the intensity of the input signal can be finely adjusted. It is composed of a pair of balance forms, so that even if one signal processing unit does not operate, it can perform a function normally.

Claims (3)

In the predistorter for improving the efficiency of high power amplifier, A signal distribution unit for distributing the input signal into two signals having a 90 ° phase difference; First and second decoupling capacitors that prevent or reduce feedback and block the flow of DC voltage components, generating a third-order signal from the input signal and extending the range of the input signal to operate but in series The signal portion including first and second Schottky diodes, a capacitor for adjusting the capacitance value of the Schottky diode, and first and second inductors separating the combination circuit of the Schottky diode and the capacitor from power and ground; Signal processing units 1 and 2 of the same structure for predistorting each signal distributed from the distribution; A temperature compensator for maintaining a constant operating characteristic according to a temperature change of the signal processors 1 and 2, including an amplifier for amplifying a signal and a thermistor whose resistance decreases when the temperature rises; And And a signal synthesizer for mixing and distributing the processed signals from the signal processors 1 and 2 and outputting the divided signals to a high output amplifier. delete delete