JP2006094424A - Power source circuit for amplitude modulation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make compatible a large-amplitude output and high efficiency in outputting a large current and to suppress a sampling component on the output side of a filter circuit. <P>SOLUTION: A comparator 1 onputs an amplitude signal and a reference triangular wave signal to produce a PWM signal. The voltage of the PWM signal is amplified by a voltage amplification unit , and the current is amplified by controlling ON/OFF of a switching circuit 3 in accordance with pulse width of the PWM signal. The amplified PWM signal is reproduced into analog amplitude signal by a filter circuit 4 and outputted to a load R1. At such a time, the switching circuit 3 and the filter circuit 4 are constituted for two or more sequences to reduce current per sequence. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an amplitude modulation power supply circuit for performing amplitude modulation by changing a power supply voltage of a high-frequency amplifier in accordance with amplitude information of a baseband signal.

  Conventionally, EER (Envelope Elimination and Restoration) modulation schemes having high-efficiency modulation amplification performance have been proposed for wireless communication devices and the like. FIG. 7 is a conceptual diagram showing a configuration of a general EER modulation method. As shown in FIG. 7, the EER modulation method performs amplitude modulation on the input amplitude information by performing desired amplitude amplification and outputs an amplitude signal, and performs phase modulation using the amplified amplitude signal as a power source. The high frequency amplifier 102 is comprised. That is, the amplitude information is amplified with high efficiency by switching in the amplitude modulation power supply circuit 101 and then added to the power supply of the high-frequency amplifier 102, and the phase information is phase-modulated with low distortion in the high-frequency amplifier 102. With such a configuration, the EER modulation method can output a desired modulation signal to the load 107 with high efficiency and low distortion.

  FIG. 8 is a circuit diagram showing a basic configuration of the amplitude modulation power supply circuit 101 in FIG. In FIG. 8, the switching pulse of the power supply circuit 101 for amplitude modulation is obtained by performing PWM (Pulse Width Modulation) control using a reference triangular wave signal and an amplitude signal. That is, when the amplitude signal and the reference triangular wave signal are input to the comparator 103, the comparator 103 generates a pulse signal (PWM signal) having a width corresponding to the amplitude of the amplitude signal. The PWM signal output from the comparator 103 is input to the voltage amplifier circuit 104 including the differential amplifier circuit of the amplifier 104 a and the amplifier 104 b and is amplified by voltage, and then each differential amplifier signal is input to the switching circuit 105. Is done. Then, the two switching elements 105a and 105b of the switching circuit 105 perform ON / OFF switching control according to the PWM duty (hereinafter referred to as PWM signal) of the differential amplification signal, and current-amplifies the high-efficiency PWM signal. . Thereafter, the filter circuit 106 composed of the inductance La and the capacitor Ca removes the sampling component (that is, noise) of the triangular wave signal from the PWM signal and reproduces the amplitude signal, which is input at the power supply terminal of the high-frequency amplifier 102 shown in FIG. .

  In this way, the amplitude modulation power supply circuit 101 amplifies the amplitude information with high efficiency and outputs the necessary power to the high-frequency amplifier 102. That is, the output signal from the amplitude modulation power supply circuit 101 is the amplified amplitude signal itself, and the power supply voltage of the high-frequency amplifier 102 varies according to the amplitude signal. It operates as a power supply circuit of the high-frequency amplifier 102 having the.

  However, in the amplitude modulation power supply circuit 101 of FIG. 8, the amplification efficiency is reduced due to the loss of reactive power caused by the charge / discharge current due to the parasitic capacitance of the switching elements 105a and 105b, as in the general power supply circuit. End up. Various measures have been proposed to prevent such efficiency reduction due to parasitic capacitance of the switching element. For example, since the magnitude of the parasitic capacitance is related to the size of the switching element, a plurality of switching elements with small current capacity are connected in parallel, and the number of switching elements in parallel is changed according to the magnitude of the load current. Has disclosed a technique for varying the parasitic capacitance and obtaining the highest efficiency in accordance with the load capacitance (see Patent Document 1). In addition, a technique is disclosed in which a switching element having a small current capacity and a switching element having a large current capacity are connected in parallel, and by switching them, optimum efficiency can be obtained in the full range of load current (see Patent Document 2). ).

These technologies minimize the ratio of reactive power due to the charge / discharge current of the parasitic capacitance to the output current amount by changing the total parasitic capacitance of the switching elements in the switching circuit according to the output current amount. The rise characteristic is improved (that is, the rise time of the current is shortened) to improve the efficiency.
JP-A-5-91745 International Publication No. 97/44884 Pamphlet

  However, when considering an actual device of an amplitude modulation power supply circuit, various problems have occurred in addition to the above-described efficiency reduction due to the parasitic capacitance of the switching element. The first problem is a problem of current limitation due to the critical current of the inductance of the filter circuit 106 shown in FIG. FIG. 9 is a characteristic diagram showing a DC current superposition characteristic in a general inductance. As shown in FIG. 9, when the direct current superimposed on the output signal increases, the inductance value decreases. This means that the direct current is limited in order to keep the inductance value constant and to have a desired filter effect. The second problem is that the amplitude and efficiency of the output signal decrease due to power loss due to the on-resistance of the switching element, the DC resistance of the inductance, and the DC resistance of the circuit. The third problem is that the sampling frequency component (that is, noise) synchronized with the triangular wave signal that is the reference signal is not completely removed even through the filter circuit 106. Therefore, the noise causes the signal of the amplitude modulation power supply circuit 101 to be removed. There is a possibility that the adjacent channel characteristic and the EVM characteristic may be deteriorated in the high frequency amplifier 102 which is the supply destination.

  The present invention has been made in view of the above points, and can achieve both a large amplitude output and high efficiency at the time of a large current output, and suppress the sampling component by the reference waveform on the output side of the filter circuit. An object of the present invention is to provide an amplitude modulation power supply circuit capable of performing the above.

  An amplitude modulation power supply circuit according to the present invention is an amplitude modulation power supply circuit for performing amplitude modulation by changing the power supply voltage of a high-frequency amplifier in accordance with a baseband amplitude signal. Comparing the potential level of the reference signal for sampling the amplitude component of the signal, PWM signal generating means for generating a PWM signal, and ON / OFF according to the pulse width of the PWM signal generated by the PWM signal generating means A switching means that performs switching control and amplifies the PWM signal, and a harmonic component removal means that removes the harmonic component of the amplified PWM signal and reproduces the amplitude signal of the analog signal. The removing unit employs a configuration in which two or more series of PWM signal generating units are used.

  According to such a configuration, when the switching means (switching circuit) and the harmonic component removal means (filter circuit) are two or more series, that is, the n series, the current flowing through the inductance of the switching element and the filter circuit is one series. 1 / n. Further, the parasitic capacitance can be reduced by reducing the current capacity of the switching element. Furthermore, the ON resistance of the switching element and the DC resistance of the inductance can be reduced to 1 / n. Therefore, the reactive power due to the parasitic capacitance can be reduced per series, and it can be operated with a current sufficiently smaller than the critical current of the inductance, and the ON resistance of the switching element and the DC resistance of the inductance The loss due to is also 1 / n. For this reason, even when a large current is output, a modulation signal having a large amplitude can be output and the efficiency of modulation amplification can be increased.

  In addition to the above configuration, the power supply circuit for amplitude modulation according to the present invention further includes control means for detecting the output current and controlling the operating state of the switching means of the plurality of series, and the control means detects According to the output current, the operation state and non-operation state of a plurality of series of switching means are individually switched for each series, and the combination of the series of switching means in the operation state is variably controlled.

  With such a configuration, the control means (control unit) detects the output current and variably controls the combination of the number and types of switching means in the operating state, so that the characteristics of the amplitude modulation power supply circuit can be adjusted according to the operating conditions. Variable. Accordingly, the power supply circuit for amplitude modulation can always be operated with the optimum amplitude modulation characteristic according to the amount of output current.

  An amplitude modulation power supply circuit according to the present invention is an amplitude modulation power supply circuit for performing amplitude modulation by varying the power supply voltage of a high-frequency amplifier according to a baseband amplitude signal. Comparing the potential level of the reference signal for sampling the amplitude component of the amplitude signal, PWM signal generating means for generating a PWM signal, ON / OFF according to the pulse width of the PWM signal generated by the PWM signal generating means PWM signal generating means comprising switching means for performing OFF switching control and amplifying the PWM signal; and harmonic component removing means for removing the harmonic component of the amplified PWM signal and reproducing the amplitude signal of the analog signal The switching means and the harmonic component removing means are each composed of two series, and the two series of PWM signal generating means have the same amplitude signal. It adopts a configuration for generating a PWM signal by inputting a reference signal of opposite phases inputs the.

  According to such a configuration, since the reference signals having opposite phases to each other are input to the two series of PWM signal generating means, the two series of sampling components (that is, noise components) cancel each other out by the opposite phases. Therefore, it is possible to output a modulated signal in which the sampling frequency component is suppressed.

  Further, the power supply circuit for amplitude modulation according to the present invention has the above-described configuration, wherein the two series of PWM signal generating means, the two series of switching means, and the two series of harmonic component removing means are configured as a set of amplitude signal generating systems. In this case, a plurality of sets of amplitude signal generation systems are connected in parallel, and the PWM signal generation means configured in each set of amplitude signal generation systems adopts a configuration in which the phases of the amplitude signals are shifted from each other. .

  According to such a configuration, a set of amplitude signal generation systems including two series of PWM signal generation means, switching means, and harmonic component removal means uses reference signals having opposite phases. In other words, noise components are canceled out and removed, and two or more sets of amplitude signal generation systems use reference signals that are out of phase with each other. Can be made.

  According to the power supply circuit for amplitude modulation of the present invention, by providing a plurality of series (n series) of switching means (switching circuit) and harmonic component removing means (filter circuit) in parallel, the current flowing through each switching element and inductance is obtained. It can be 1 / n. Thereby, since the current capacity of the switching element can be reduced, the parasitic capacity of the switching element can be reduced and the reactive current can be reduced. Furthermore, it is possible to reduce the power loss by reducing the ON resistance and inductance of the switching element and the DC resistance of the circuit to 1 / n. Further, the loss due to the influence of the direct current superimposition characteristic of the inductance can be reduced to 1 / n. As a result, it is possible to realize a power supply circuit for amplitude modulation of a high-frequency amplifier that operates with high amplitude, large current output and high efficiency.

  In addition, according to the power supply circuit for amplitude modulation of the present invention, the sampling frequency component that becomes a noise component is removed by synthesizing the amplitude modulation signals sampled by the reference signals having opposite phases to each other on the output side of the filter circuit. Therefore, a stable amplitude modulation signal with less noise can be supplied to the power supply of the high frequency amplifier. As a result, high-efficiency performance is required, and it can be applied to a power supply circuit for a high-frequency amplifier such as a communication device having strict specifications for transmission spurious. Further, according to the power supply circuit for amplitude modulation of the present invention, the PWM signal generating means (comparator), the switching means (switching circuit), and the second harmonic component removing means (filter circuit) are configured in a number of series, and By using a plurality of reference signals whose phases are shifted, the sampling accuracy of the amplitude signal can be further improved.

  The power supply circuit for amplitude modulation according to the present invention compares a reference triangular wave signal and an amplitude signal by a comparator, performs PWM control on the amplitude signal according to the amplitude, and performs voltage amplification to generate a desired PWM signal. is doing. Then, the switching circuit is turned on / off in accordance with the pulse width of the generated PWM signal to amplify the current, and then the harmonic component is removed by the filter circuit to reproduce the amplitude signal of the analog signal again. Supplying power. At this time, the current distribution is achieved by dividing the switching circuit and the filter circuit into two or more series. Thereby, the constant of each component per series can be reduced, and the current flowing through each series of switching elements and filter elements (inductance, etc.) can be reduced. Therefore, the reactive power can be reduced by reducing the parasitic capacitance caused by the miniaturization of the switching element, the inductance current can be reduced by reducing the inductance constituting the filter, and the ON resistance of the switching element and the DC resistance of the inductance can be reduced. be able to. Therefore, the parasitic capacitance per series is reduced and the efficiency is improved, and it is possible to operate with a current sufficiently smaller than the critical current of the inductance, and the loss due to the ON resistance of the switching element and the DC resistance of the inductance Can be reduced. As a result, even when a large current is output, it is possible to output a large amplitude signal and increase the efficiency.

  Hereinafter, some embodiments of the power supply circuit for amplitude modulation according to the present invention will be described in detail with reference to the drawings. In the drawings used in the embodiments, the same components are denoted by the same reference numerals, and redundant description is omitted as much as possible.

<Embodiment 1>
FIG. 1 is a circuit diagram of an amplitude modulation power supply circuit according to Embodiment 1 of the present invention. The power supply circuit for amplitude modulation is the power supply circuit for amplitude modulation 101 for power supply of the high-frequency amplifier 102 used in the above-described EER modulation system of FIG. 7, but the EER modulation system is a known technique as described above. The description is omitted.

  In FIG. 1, an amplitude modulation power supply circuit includes a comparator (PWM signal generation means) 1 that generates PWM signals by performing PWM control using an amplitude signal and a triangular wave signal that is a reference for sampling the amplitude signal, and a PWM signal. The current of the PWM signal is extremely efficiently controlled by ON / OFF control according to the pulse width of the PWM signal, and the voltage amplifying unit 2 including a differential amplifier circuit of the amplifier 2a1 and the amplifier 2a2 that amplifies the signal to a desired voltage level. A switching circuit (switching means) 3 for performing amplification, and a filter circuit (harmonic component removing means) 4 for regenerating the amplitude signal input to the comparator 1 by converting the PWM signal output from the switching circuit 3 into an analog signal again. The load R1 is connected.

  The switching circuit 3 has a configuration in which switching circuits 3a, 3b, and 3n of a plurality of series (three series in the figure) are connected in parallel in a combination in which two switching elements are alternately turned ON / OFF. The combinations of the two switching elements in each of the switching circuits 3a, 3b, and 3n are the switching element 3a1 and the switching element 3a2, the switching element 3b1 and the switching element 3b2, and the switching element 3n1 and the switching element 3n2, respectively. The filter circuit 4 has a configuration in which the inductances L1, L2, and Ln are connected in parallel in a plurality of series (three series in the figure) corresponding to the switching circuits 3a, 3b, and 3n. Note that the capacitor C1 constituting the filter circuit 4 is common to each of the inductances L1, L2, and Ln and is constituted by one piece. In this way, the switching circuit 3 and the filter circuit 4 are connected in parallel across a plurality of series.

  Next, the operation of the amplitude modulation power supply circuit shown in FIG. 1 will be described. First, the comparator 1 receives an amplitude signal and a reference signal for sampling the amplitude signal, for example, a triangular wave signal. Note that the frequency of the triangular wave signal is sufficiently higher than the frequency of the amplitude signal. The comparator 1 compares the amplitudes of the amplitude signal and the triangular wave signal (that is, compares the potential levels of the two waveforms), and generates and outputs a PWM signal whose pulse width changes according to the magnitude. The PWM signal is input to the amplifier 2a1 and the amplifier 2a2 in the voltage amplifying unit 2, and a PWM signal divided into two with a phase difference of 180 ° is generated and amplified to a desired voltage required by the high-frequency amplifier. Further, the amplified PWM signal is inverted in each of the switching elements 3a1 and 3a2, the switching elements 3b1 and 3b2, and the switching elements 3n1 and 3n2 in the switching circuits 3a, 3b, and 3n, and the other is Output as normal.

  The switching circuits 3a, 3b, and 3n perform ON / OFF switching of the switching elements 3a1 and 3a2, the switching elements 3b1 and 3b2, and the switching elements 3n1 and 3n2, respectively, according to the High and Low of the PWM signal. Highly efficient current amplification is performed on the PWM signal. Further, the respective PWM signals amplified by the switching circuits 3a, 3b, and 3n are input to the filter circuit 4 including the inductances L1, L2, and L3 of each series and the common capacitor C1. Then, the filter circuit 4 removes the sampling component (that is, noise) depending on the triangular wave signal from each series of PWM signals, and reproduces the original amplitude signal, that is, the amplitude signal input to the comparator 1, and the load R 1. (That is, input to the power supply terminal of the high-frequency amplifier 102 in FIG. 7).

  At this time, if the total number of series of the switching circuit 3 and the filter circuit 4 is n, each series is connected in parallel, so that one series in each switching circuit 3a, 3b, 3n and inductance L1, L2, Ln. The amount of current flowing per hit is 1 / n of the total output current. Therefore, the upper limit value of the output current limited by the DC current superposition characteristics of the inductances L1, L2, and Ln is improved by n times compared to the case where the filter circuit 4 is configured in one series. In addition, since each switching circuit 3a, 3b, 3n and filter circuit 4 of each series are connected in parallel, the parasitic capacitance and ON resistance of each switching element are 1 / n, and the DC resistance of the inductance and The DC resistance of the circuit is also 1 / n. As a result, the reactive power due to the parasitic capacitance becomes 1 / n, and the power loss due to the resistance becomes 1 / n, thereby greatly improving the amplitude characteristic and the efficiency characteristic.

  Here, since switching elements having different current capacities can be used for some or all of the switching circuits 3a, 3b, 3n connected in parallel, in this case, switching elements having different current capacities according to the currents. Is selected, the DC current superimposition characteristics can be improved in the same manner as described above. Even when switching elements having different current capacities are selected in this way, the DC resistance value as a whole becomes the parallel resistance value of the DC resistance values of each series, so that the parasitic circuit is more parasitic than the case where the switching circuit is configured in one series. Capacitance and ON resistance are reduced. Therefore, loss due to parasitic capacitance and resistance is reduced, and therefore amplitude characteristics and efficiency characteristics are improved.

<Embodiment 2>
Next, an amplitude modulation power supply circuit according to Embodiment 2 of the present invention will be described. FIG. 2 is a circuit diagram of a power supply circuit for amplitude modulation according to the second embodiment of the present invention. In the second embodiment shown in FIG. 2, in addition to the configuration of FIG. 1, the control units (control means) 7a and 7b that can turn on / off the operating state and the non-operating state of each series of switching circuits 2a and 2b are provided for each series. It was set as the preparation for every. That is, as shown in FIG. 2, the series resistor R0 is inserted into the output circuit of the amplitude modulation power supply circuit, and the control units 7a and 7b detect the output current flowing through the series resistor R0 to detect the switching circuits 2a, It is configured to control the 2b parallel connection configuration.

  2, for the sake of simplicity of explanation, the switching circuit 3 and the filter circuit 4 shown in FIG. 1 are divided into two systems, and the voltage amplification unit 2 and the switching circuit 3 are collectively set as a switching circuit in a broad sense. The switching circuit 2a and the switching circuit 2b are used respectively. The switching circuit 2a includes amplifiers 2a1 and 2a2 and switching elements 3a1 and 3a2. The switching circuit 2b includes amplifiers 2b1 and 2b2 and switching elements 3b1 and 3b2.

  In FIG. 2, for example, a 1-watt FET is used for each switching element 3a1, 3a2 of the switching circuit 2a, and a 4-watt FET is used for each switching element 3b1, 3b2 of the switching circuit 2b. In this way, the amplitude characteristic and the efficiency characteristic can be improved by using the FETs having different rated capacities for each series of switching circuits.

  FIG. 3 is a characteristic diagram showing the amplitude characteristics of the amplitude modulation power supply circuit according to the second embodiment of the present invention. The horizontal axis represents the output current, and the vertical axis represents the output voltage corresponding to the amplitude. FIG. 4 is a characteristic diagram showing the efficiency characteristics of the amplitude modulation power supply circuit according to the second embodiment of the present invention, where the horizontal axis represents the output current and the vertical axis represents the efficiency. Hereinafter, the operation for realizing the improvement of the amplitude and the efficiency in the second embodiment will be described with reference to FIG. 2, FIG. 3, and FIG.

  The comparator 1 receives an amplitude signal and a triangular wave signal that serves as a reference signal for sampling the amplitude signal. The comparator 1 compares the magnitudes of the amplitudes of these two signal waveforms, and generates and outputs a PWM signal whose pulse width changes according to the magnitude. Further, high-efficiency amplification is performed by the switching circuits 2a and 2b. After the sampling component (noise) is removed by the filter circuit 4, the waveform of the amplitude signal is reproduced and output to the high-frequency amplifier.

  At this time, the control unit is connected to the output side of the amplitude modulation power supply circuit by a method such as inserting a series resistor R0 that does not cause power consumption or voltage drop to be a practical problem and detecting the voltage drop of the series resistor R0. 7a and the controller 7b detect the amount of output current. Then, the control unit 7a and the control unit 7b switch between the operating state and the non-operating state of the switching circuits 2a and 2b for each series according to the respective current detection levels.

  By performing such switching control by the control units 7a and 7b, the amplitude characteristic and the efficiency characteristic of the amplitude modulation power supply circuit can be changed according to the output current. For example, as shown in FIG. 3, when the input amplitude signal is small, that is, where the output current is small (0.05 A or less), the operation is performed with the characteristic (a) of 1 watt (W), and the output current value is medium. At a certain level (0.1 A or less), the operation is performed with the characteristic (b) of 4 W, and when the amplitude signal on the input side is large, that is, where the output current is large (0.1 A or more), the characteristic (c) of 1 W + 4 W is obtained. By always operating at a high output voltage, that is, a high amplitude characteristic can be maintained. Similarly, as shown in FIG. 4, when the amplitude signal on the input side is small, that is, where the output current is small (0.05 A or less), the operation is performed with the characteristic (a) of 1 W, and the output current value is medium. However, at (0.35 A or less), the operation is performed with the characteristic (b) of 4 W, and when the input side amplitude signal is large, that is, where the output current is large (0.35 A or more), the operation is performed with the characteristic (c) of 1 W + 4 W By doing so, high efficiency characteristics can always be maintained.

<Embodiment 3>
Next, an amplitude modulation power supply circuit according to Embodiment 3 of the present invention will be described. FIG. 5 is a circuit diagram of an amplitude modulation power supply circuit according to Embodiment 3 of the present invention. The third embodiment shown in FIG. 5 employs a configuration in which the voltage amplifying unit 2, the switching circuit 3, and the filter circuit 4 are arranged in two series in the configuration shown in FIG. 1, and an input-side comparator is arranged for each series. Yes. That is, as shown in FIG. 5, the first series includes a comparator 1a, a voltage amplifying unit 2a including amplifiers 2a1 and 2a2, a switching circuit 3a including switching elements 3a1 and 3a2, and a filter circuit 4 including an inductance L1. The second series includes a comparator 1b, a voltage amplifying unit 2b including amplifiers 2b1 and 2b2, a switching circuit 3b including switching elements 3b1 and 3b2, and a filter circuit 4 including an inductance L2.

  In other words, the comparators 1a and 1b, the switching circuits 2a and 2b, and the inductances L1 and L2 of the filter circuit 4 are arranged in two series in parallel, and an amplitude signal having the same amplitude and the same frequency is input to the two comparators 1a and 1b. Yes. However, the triangular wave signal, which is a reference signal for sampling the amplitude signal, is input so as to be opposite in phase between the two comparators 1a and 1b, and the PWM control is performed by the respective comparators 1a and 1b. ing.

  Next, the operation of the amplitude modulation power supply circuit shown in FIG. 5 will be described. First, amplitude signals having the same frequency and the same amplitude are input to the comparators 1a and 1b. On the other hand, the triangular wave signal serving as the reference signal is input to the comparator 1a and the comparator 1b in opposite phases. The comparator 1a and the comparator 1b respectively compare the amplitudes of the amplitude signal and the triangular wave signal, and output a PWM signal whose pulse width changes according to the magnitude. The PWM signal output from the comparator 1a is input to the amplifiers 2a1 and 2a2 in the voltage amplifier 2a, and the PWM signal output from the comparator 1b is input to the amplifiers 2b1 and 2b2 in the voltage amplifier 2b. Then, each of the voltage amplification units 2a and 2b performs voltage amplification to a desired level required by the high frequency amplification unit. Further, the PWM signals output from the voltage amplification units 2a and 2b are respectively input to the switching circuits 3a and 3b and amplified with high efficiency, and the sampling components are removed by the filter circuit 4 for each series. An amplitude modulation signal is synthesized on the output side.

  Here, in Embodiment 3, since the triangular wave signals having opposite phases to each other are input to the comparators 1a and 1b, the sampling component (F1) on the output side of the comparator 1a and the sampling component (F2) on the output side of the comparator 1b. As shown in the corresponding part of FIG. 5, the signals have opposite polarities at all frequencies (f1, 2f1, 3f1,... Nf1) other than the reference frequency f0. Accordingly, the amplified sampling component (F3) output from one series of switching circuits 3a and the amplified sampling component (F4) output from another series of switching circuits 3b are also shown in the corresponding portions of FIG. In this way, the signals have opposite polarities at all frequencies (f1, 2f1, 3f1,... Nf1) other than the reference frequency f0. Therefore, since two amplitude signals having sampling components (F3 and F4) having frequencies opposite to each other are synthesized on the output side of the filter circuit 4, out of the sampling components of both series, the frequencies having opposite polarities. Since the components (f1, 2f1, 3f1,..., Nf1) cancel each other, as a result, the sampling frequency component that becomes noise is reduced and the amplitude signal (F5) of the necessary frequency component f0 is output.

<Embodiment 4>
Next, an amplitude modulation power supply circuit according to Embodiment 4 of the present invention will be described. FIG. 6 is a circuit diagram of a power supply circuit for amplitude modulation according to the fourth embodiment of the present invention. In the fourth embodiment shown in FIG. 6, the comparators 1a and 1b, the voltage amplification circuits 2a and 2b, the switching circuits 3a and 3b, and the inductances L1 and L2 of the filter circuit 4 of the third embodiment shown in FIG. The configuration is such that two sets of connected circuits are connected in parallel. Of course, it is good also as a structure which connected 2 or more sets in parallel. In addition, in describing the operation unique to the fourth embodiment with reference to FIG. 6, if individual symbols are assigned to the respective groups (the first group and the second group), the codes become complicated. In FIG. 6, the first set and the second set are given the same reference numerals as in FIG.

  In FIG. 6, the operation in which the first group and the second group each output an amplitude signal is exactly the same as the content described in the third embodiment, and thus a duplicate description is omitted. In the fourth embodiment, triangular wave signals having opposite phases are input to the comparator 1a and the comparator 1b of the comparator 1ab of the first set 10, and the comparator 1a and the comparator 1b of the comparator 1ab of the second set 20 are reversed to each other. Inputting a phase triangular wave signal is exactly the same as in the third embodiment shown in FIG. The feature of the fourth embodiment is that the phase of the triangular wave signal is shifted between the comparators 1a and 1b of the first set 10 and the comparators 1a and 1b of the second set 20. For example, as shown in FIG. 6, a triangular wave signal having a phase of 0 ° and 180 ° is input to the comparator 1a of the first set 10, and 90 ° and the comparator 1b are input to the comparator 1a of the second set 20. A triangular wave signal having a phase of 270 ° is input.

  In this way, the triangular wave of the first set 10 and the second set 20 is shifted between the first set 10 and the second set 20 by shifting the phases of the triangular wave signals input to the comparators 1a and 1b. Since the amplitude signal sampled by the signal is synthesized by the filter circuit 4, as a result, the amplitude signal sampled by the double sampling point is synthesized. In other words, since the amplitude signals sampled at different sampling timings in the first set 10 and the second set 20 are synthesized on the output side of the filter circuit 4, the reproduced amplitude signals are equivalent. In other words, the signal sampled by the double sampling point is restored.

  Therefore, rather than sampling at the frequency of the triangular wave signal input to the pair of comparators 1a and 1b as shown in FIG. 5, the signals are input to the two sets of comparators 1a and 1b as shown in FIG. 6 at different frequencies. Sampling at the frequency of the triangular wave signal further improves the sampling accuracy. At this time, as described with reference to FIG. 5, since the triangular wave signals having opposite phases are input to the comparators 1a and 1b of the first set 10, the noise components of the sampling components cancel each other, and Since the opposite phase triangular wave signals are also input to the comparators 1a and 1b of the second set 20, the noise components of the sampling components cancel each other. As a result, in the fourth embodiment, it is possible to improve the sampling accuracy and output an amplitude signal in which the sampling component is suppressed, as in the case of increasing the frequency of the triangular wave signal.

  As described above, the amplitude modulation power supply circuit according to the present invention can supply a high-current, large-amplitude amplitude signal to a high-frequency amplifier with high efficiency and sufficiently suppress a sampling component that becomes a noise component. be able to. Therefore, the power supply circuit for amplitude modulation according to the present invention is applied to a high-frequency amplifier of a communication device such as a base station device or a terminal device in mobile communication that requires high efficiency performance and has strict specifications for transmission spurious. can do.

Circuit diagram of power supply circuit for amplitude modulation in Embodiment 1 of the present invention Circuit diagram of power supply circuit for amplitude modulation according to the second embodiment of the present invention The characteristic view which shows the amplitude characteristic of the power supply circuit for amplitude modulation in Embodiment 2 of this invention FIG. 7 is a characteristic diagram showing the efficiency characteristic of the amplitude modulation power supply circuit according to the second embodiment of the present invention. Circuit diagram of power supply circuit for amplitude modulation in Embodiment 3 of the present invention Circuit diagram of power supply circuit for amplitude modulation according to the fourth embodiment of the present invention Conceptual diagram showing the configuration of a general EER modulation system FIG. 7 is a circuit diagram showing the basic configuration of the amplitude modulation power supply circuit. Characteristic diagram showing DC current superposition characteristics in general inductance

Explanation of symbols

1, 1a, 1b, 1ab comparator (PWM signal generating means)
2, 2a, 2b Voltage amplification unit 3, 3a, 3b, 3n Switching circuit (switching means)
4 Filter circuit (Harmonic component removal means)
7a, 7b Control unit (control means)

Claims (4)

A power supply circuit for amplitude modulation for performing amplitude modulation by changing a power supply voltage of a high-frequency amplifier according to an amplitude signal of a baseband,
PWM signal generating means for comparing the potential level of the amplitude signal with the potential level of a reference signal for sampling the amplitude component of the amplitude signal, and generating a PWM signal;
Switching means for performing ON / OFF switching control according to the pulse width of the PWM signal generated by the PWM signal generating means, and amplifying the PWM signal;
A harmonic component removing means for removing the harmonic component of the amplified PWM signal and reproducing the amplitude signal of the analog signal;
2. The amplitude modulation power supply circuit according to claim 1, wherein the switching means and the harmonic component removing means are configured in two or more series with respect to one series of the PWM signal generating means. Furthermore, it comprises a control means for detecting the output current and controlling the operating state of the switching means of a plurality of series,
The control means individually switches the operation state and non-operation state of the plurality of series of the switching means for each series according to the detected output current, and variably controls the combination of the series of switching means in the operating state. The power supply circuit for amplitude modulation according to claim 1. A power supply circuit for amplitude modulation for performing amplitude modulation by changing a power supply voltage of a high-frequency amplifier according to an amplitude signal of a baseband,
PWM signal generating means for comparing the potential level of the amplitude signal with the potential level of a reference signal for sampling the amplitude component of the amplitude signal, and generating a PWM signal;
Switching means for performing ON / OFF switching control according to the pulse width of the PWM signal generated by the PWM signal generating means, and amplifying the PWM signal;
A harmonic component removing means for removing the harmonic component of the amplified PWM signal and reproducing the amplitude signal of the analog signal;
The PWM signal generating means, the switching means, and the harmonic component removing means are each composed of two series,
Two series of PWM signal generation means input the same amplitude signal and input the reference signals having opposite phases to each other to generate the PWM signal.   When the two series of PWM signal generation means, the two series of switching means, and the two series of harmonic component removal means are configured as a set of amplitude signal generation systems, a plurality of sets of the amplitude signal generation systems are arranged in parallel. 4. The power supply circuit for amplitude modulation according to claim 3, wherein the PWM signal generation means connected to each other and configured in each set of the amplitude signal generation systems inputs the phases of the amplitude signals shifted from each other. 5. .

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