JP2004201123A - Amplitude modulation transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that distortion occurs in an amplitude modulation signal due to the error of a plurality of power amplifiers to an ideal value, in particular due to the deviation in a rise/fall time when the individual power amplifiers are switched about driving of the power amplifiers in a transmitter of an amplitude modulation system by digital modulation control. <P>SOLUTION: An amplitude modulation transmitter is provided with: a first amplifying part for amplifying the amplitude of a signal of a device on the basis of a first scale factor signal and outputting a first amplified signal; a driving part for amplifying the amplitude of the amplified signal on the basis of a second scale factor signal and driving the output signals of the first amplifying part and a second amplifying part with a rectangular wave; and a combining part for combining the first amplified signal with the second amplified signal and outputting the combined signal as an output signal. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an amplifier and a transmitter. In particular, the present invention relates to a modulation / demodulation type transmitter using digital modulation / demodulation control.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an amplitude adjustment method based on digital modulation / demodulation control, for example, there is a method disclosed in JP-A-2000-232380. In this method, a plurality of power amplifiers are directly turned “on” and “off” by digital signals, and all information (bits) of a modulation signal is modulated and amplified.
[0003]
A conventional transmitter and receiver of the modulation and demodulation method based on digital modulation and demodulation control will be described with reference to FIGS. In the conventional transmitting device 50, the input of the modulation signal (voice) is converted into a 12-bit digital signal by the A / D converter 1, and then the encoder 2 uses the MSB (Most Significant Bit) -side predetermined bit to transmit the PA1. 26 binary step PAs (binary power amplifiers) of PA1 / 2 to 1/64 using 26 big step PAs (equal output power amplifiers) 3 to 26 and predetermined bits on the LSB (Least Significant Bit) side 4 ON / OFF control. The EX (exciter PA) 6 amplifies the carrier signal of the frequency F0 output from the OSC (carrier oscillator) 5 to a predetermined level, and uses the carrier signal passed through the LC filter (notch filter) 10 to generate a big step PA ( An equal output power amplifier 3 and a binary step PA (binary power amplifier) 4 are driven. The power amplifier supplies the amplified output signal to the output synthesis unit 7.
[0004]
[Problems to be solved by the invention]
However, in the conventional amplitude modulation method based on digital modulation control, in order to drive the power amplifier directly with the carrier wave F0 output from the OSC in order to simplify the device and reduce the cost, the carrier wave F0 output from the OSC is required. (Square wave) needs to be amplified by the exciter PA, and it has to be passed through an LC filter in order to remove unnecessary high frequency components from the amplified carrier. However, this power amplifier drive signal is converted into a sine wave by passing through the LC filter. In the conventional method of directly driving a power amplifier with a sine wave, variations in individual amplifiers, in particular, variations in switching resistance / capacitance cause rise / fall time deviations in switching in individual power amplifiers. In addition, the driving method of the power amplifier using the sine wave has a problem that the amplitude modulation signal is distorted due to a large time lag due to a change in voltage. The error also changes due to power supply fluctuation, temperature change, aging, and the like.
[0005]
[Means for Solving the Problems]
[0006]
That is, according to the first embodiment of the present invention,
[0007]
In an amplitude modulation transmitting apparatus for amplifying a signal to be amplified based on a first magnification signal specifying an amplification factor of a signal to be amplified and a second magnification signal, an amplitude of the signal to be amplified is determined based on the first magnification signal. A first amplifier that outputs a first amplified signal to be amplified, a second amplifier that outputs a second amplified signal that amplifies the amplitude of the signal to be amplified based on the second magnification signal, and the first amplifier And a driving unit that drives the output signal of the second amplifying unit by a rectangular wave, and combines the first amplified signal, the second amplified signal, and the third amplified signal to generate an output signal of the amplifying device. And an output synthesizing unit.
[0008]
Note that the above summary of the present invention does not enumerate all the necessary features of the present invention, and a sub-combination of these features can also be an invention.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described through embodiments of the present invention. However, the following embodiments do not limit the invention according to the claims, and all of the combinations of the features described in the embodiments are not limited thereto. It is not always essential to the solution of the invention.
[0010]
A transmitter and receiver of a modulation / demodulation system based on digital modulation / demodulation control of the present invention will be described with reference to FIG. The transmitting device 100 is a transmitter that outputs an amplitude-modulated signal obtained by amplifying the amplitude of the signal to be amplified at an amplification rate based on the modulation signal, and includes a high-frequency oscillator 24 that generates a carrier signal, and the amplitude of the signal to be amplified. An A / D converter 20 that converts the digital signal into a plurality of bits; an encoder 21 that outputs the output signal of the A / D converter 20 and a switching signal of a first amplifier 22 and a second amplifier 23; A PA driver 25 for driving the first amplifier 22 and the second amplifier 23, an output synthesizer 26 (synthesis transformer) for voltage-synthesizing the outputs of the first amplifier 22 and the second amplifier 23, A band-pass filter 27 for removing unnecessary high-frequency components from the output from the output combining section 26;
[0011]
The first A / D converter 20 outputs a signal obtained by A / D-converting the modulated signal AMS to the encoder 20 as a magnification specifying signal MAS, which is a plurality of digital signals. In the present embodiment, the first A / D converter 10 outputs the upper 5 bits of the magnification designation signal MAS as the first magnification signal HBS and the lower 6 bits as the second magnification signal LBS.
[0012]
In the present embodiment, the encoder 20 receives the magnification signal MAS, which is an 11-bit digital signal, and sets the first operation signals (HBS-1 to HBS-26) using the upper 5 bits of the magnification signal as the first magnification signal. Output. When the number represented by the first magnification signal HBS is k (k is an integer satisfying 1 ≦ k ≦ 26), the encoder 20 outputs a logical value of 1 as the first operation signal (HBS-1 to HBS-k). Is output. When the number represented by the first magnification signal HBS is 0, the encoder 20 outputs a logical value 0 as the first operation signal (HBS-1 to HBS-26). The encoder 20 outputs a logical value 1 as the first operation signals (HBS-1 to HBS-9), for example, when the value indicated by the first magnification signal HBS as a binary number is “01001”.
[0013]
In the present embodiment, the encoder 20 receives the magnification signal MAS, which is a digital signal of 11 bits, and uses the lower 6 bits of the magnification signal as a second magnification signal to generate second operation signals (LBS-1 to LBS-6). Is output.
[0014]
The first amplifier 22 amplifies the amplitude of the carrier signal F0 based on the first magnification signal HBS, and outputs a first amplified signal BHS. The second amplifier 23 amplifies the amplitude of the carrier signal F0 based on the second magnification signal LBS, and outputs a second amplified signal BLS. The second amplifier 23 preferably outputs a second amplified signal BLS whose amplitude is smaller than the amplitude of the first amplified signal BHS.
[0015]
The first amplifying section 23 preferably includes a plurality of first amplifiers. In the present embodiment, the first amplifying unit 23 includes 26 first amplifiers (big steps PA). The first amplifiers (PA1 to PA26) are power amplifiers each having an equal amplification factor.
[0016]
Each of the first amplifiers receives one operation signal HBS from the plurality of first operation signals (HBS-1 to HBS-26) output from the encoder 20. The first amplifier 22 receives one first operation signal HBS and the carrier signal F0, and amplifies the amplitude of the carrier signal F0 at a predetermined amplification factor when the first operation signal HBS takes a predetermined logic value. It is preferable to output the first amplified signal BHS. The first amplifier PAm (m is an integer satisfying 1 ≦ m ≦ 26) is a first amplifier that amplifies the amplitude of the carrier signal F0 at a predetermined amplification factor when the first operation signal HBS-m is 1. Outputs the amplified signal BHS-m.
[0017]
The second amplifying unit 23 preferably has a plurality of second amplifiers 1/2 ⁿ PA (n is an integer satisfying 1 ≦ n ≦ 6). In the present embodiment, the second amplifying unit 23 includes six second amplifiers (binary steps PA) (1 / 2PA to 1 / 64PA). In the present embodiment, assuming that the amplification rate of the first amplifiers (PA1 to PA26) of the first amplifier unit 22 or the amplified output voltage is A, the second amplifier 1/2 ⁿ PA (n is 1 ≦ n ≦ 6). Is an integer satisfying A / 2 ⁿ ). That is, the second amplifier 1 / 2PA is A / 2, and the second amplifier 1 / 64PA is A / 64.
[0018]
Each of the second amplifiers 1/2 ⁿ PA receives one operation signal LBS from the plurality of second operation signals (LBS-1 to LBS-6) output from the encoder 21. The second amplifier 1/2 ⁿ PA preferably receives one second operation signal LBS and the carrier signal F0, and outputs a second amplified signal BLS obtained by amplifying the amplitude of the carrier signal F0 at a predetermined amplification factor. . When the second operation signal LBS-n is 1, the second amplifier 1/2 ⁿ PA (n is an integer satisfying 1 ≦ n ≦ 6) increases the amplitude of the carrier signal F0 at a predetermined amplification factor. It outputs the amplified first amplified signal BLS-n.
[0019]
In the modulation / demodulation method according to the digital modulation / demodulation control of the present invention, a driving method of the power amplification unit will be described with reference to FIG. The PA driving unit 25 performs driving by causing the first amplification unit (big step PA) 22 and the second amplification unit (binary step PA) 23 to perform a class D amplification operation. In the present embodiment, the carrier wave F0 (rectangular wave) output from the OSC 24 is converted into gate input signals having phases opposite to each other, input to the FET driver IC 29, and output the respective gate input signals to the gates of the FET Q8 and the FET Q9. The FETs Q8 and Q9 alternately perform ON / OFF operations in accordance with the input gate input signal, and perform a push-pull operation centering on the primary side middle point of the pulse transformer 32. By repeating the ON / OFF operation, the switching operations of the FETs Q10 to Q13 on the secondary side of the transformer are performed, and the D-class amplification operation is performed by a combination of the ON / OFF operations. The ON / OFF control of the BH signal output from the first amplifying unit 22 or the BL signal output from the second amplifying unit 23 is performed by inputting the first operation signal HB or the second operation signal LB output from the encoder 21 to the FET Q14. The switching operation is performed.
[0020]
The output combining unit 26 connects each of the first amplifiers (PA1 to PA26) and each of the second amplifiers (1 / 2PA to 1 / 64PA) by transformer coupling. The output synthesizing unit 60 outputs the first amplified signals (BHS-1 to BHS-26) output from the first amplifiers (32-1 to 32-26) and the second amplifier (342) via the transformer coupling. -1 to 342-6) to receive the second amplified signals (BLS-1 to BLS-6). The combining unit 206 grounds one end of both ends of the secondary side coil connected in series, and outputs a signal generated at the other end as an amplitude modulation signal AAS. The combining unit 206 may output the amplitude modulation signal AAS as an antenna output, for example.
[0021]
According to the present embodiment, the transmitter 100 removes the distortion of the amplitude modulation AAS in which the first amplified signal BHS output from the first amplifier 22 and the second amplified signal LBS output from the second amplifier 23 are combined. Compensation and stable transmission can be performed.
[0022]
Further, the transmitter 100 may be applied to a wireless transceiver. The wireless transceiver may be, for example, a base station or a mobile station. In this case, the wireless transceiver includes an antenna, a common unit, a receiving unit, and a transmitting unit. The common unit is electrically connected to the antenna, the receiving unit, and the transmitting unit, and eliminates an interaction between a transmission signal and a reception signal when the antenna transmits and receives a signal. The receiving unit is a demodulation circuit that demodulates a received signal. The transmitting unit is the transmitter 100. Also in this case, the radio transceiver can compensate for distortion generated in the amplitude modulation signal output from the transmission unit and perform stable transmission.
[0023]
As described above, the present invention has been described using the embodiment, but the technical scope of the present invention is not limited to the above embodiment. Various changes or improvements can be added to the above embodiment. It is apparent from the description of the appended claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.
【The invention's effect】
[0024]
As is apparent from the above description, according to the present invention, in the transmitter of the amplitude modulation system by the digital modulation control, the distortion generated in the amplitude modulation signal output from the transmitter can be reduced. In addition, by using a general-purpose FET-IC for driving the amplifier, the driving power of the power amplifier can be reduced.
[Brief description of the drawings]
FIG. 1 shows a configuration of a transmission device according to an embodiment of the present invention.
FIG. 2 shows a driving method of a power amplification unit according to the present invention.
FIG. 3 shows a configuration of a transmission device according to a conventional embodiment.
FIG. 4 shows a driving method of a conventional power amplifier.
[Explanation of symbols]
50,100: transmitting device, 1,20: first A / D converter, 2,21: encoder, 3,22: first amplifier (big step PA), 4,23: second amplifier (binary step PA), 5,24: Carrier oscillator, 6: Exciter PA, 7,26: Output synthesis unit (synthesis transformer), 8,27: Bandpass filter, 10: LC filter, 27: Bandpass filter, 25: PA drive unit

Claims (1)

In an amplitude modulation transmitting apparatus for amplifying a signal to be amplified based on a first magnification signal designating an amplification factor of a signal to be amplified and a second magnification signal,
A first amplification unit that outputs a first amplification signal that amplifies an amplitude of the amplified signal based on the first magnification signal;
A second amplifier that outputs a second amplified signal that amplifies the amplitude of the signal to be amplified based on the second magnification signal;
A drive unit that drives the output signal of the first amplification unit and the second amplification unit by a rectangular wave;
A combining unit that combines the first amplified signal, the second amplified signal, and the third amplified signal and outputs the combined signal as an output signal of the amplifying device;
An amplitude modulation transmission device comprising:

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