JPH02223255A - transmitting device - Google Patents

Abstract

PURPOSE:To transmit a signal having envelope fluctuation after amplifying with superior power efficiency without deteriorating spectrum outside the band area by generating two systems of frequency-modulated waves based on an inputted modulation signal, then, synthesizing them. CONSTITUTION:A signal wave including the signal wave having the envelope fluctuation is separated to the two systems of frequencymodulated waves, and a phase error generated by the difference of initial phases of frequency modulation means 22 and 23 is synthesized at a hybrid circuit 25 after correcting at correction circuits 26-29. Thereby, it is possible to comprise transmission equipment with transmission capability of superior power efficiency without increasing a circuit scale as keeping the spectrum outside the band area of the signal wave including the signal wave having the envelope fluctuation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmitting device used for digital wireless communication.

[Conventional technology]

Generally, in order to improve the power efficiency when amplifying a signal in a transmitting device, it is necessary to use a nonlinear amplifier that performs an amplification operation in a saturation region.

On the other hand, a normal signal is accompanied by a change in its envelope, and when such a signal is amplified by a nonlinear amplifier, waveform distortion occurs due to the nonlinearity of the amplifier.

When such waveform distortion occurs, the out-of-band spectral characteristics of the signal are significantly degraded, resulting in an increase in the required bandwidth.

Therefore, when amplifying a signal with envelope fluctuations as described above, avoid using a nonlinear amplifier in the saturation region, and try to lower the output to some extent and perform amplification in the region where the amplitude characteristics are linear. I have to. When amplifying a signal by taking output back-off in this manner, it is possible to amplify the signal while keeping the out-of-band spectrum of the signal well.

[Problem to be solved by the invention]

By the way, as a technique for amplifying a linearly modulated wave having envelope fluctuations without deteriorating the out-of-band spectrum and with good power efficiency, the present applicant has proposed Japanese Patent Application No. 11409/1986.
No. 8r amplifier 1 has already been proposed. This is a technique in which a linearly modulated wave is decomposed into two systems of constant envelope modulated waves, and these two systems of constant envelope modulated waves are amplified and then combined.

FIG. 5 shows a specific example of a transmitting device to which this technique is applied.

In the figure, a waveform generation circuit 51 generates two systems of orthogonal modulation signals based on the introduced linear modulation signal. Here, these two systems of orthogonal modulation signals are generated so that the introduced linear modulation signal is reproduced by combining them.

Each of the orthogonal modulators 52 and 53 modulates the carrier wave supplied from the oscillator 54 using the introduced orthogonal modulation signal, and outputs two systems of constant envelope modulated waves.

Each of the power amplifiers 55 and 56 operates in a saturation region (nonlinear region) where high power efficiency can be obtained;
Amplify each of the constant envelope modulated waves of the system. The outputs of the power amplifiers 55 and 56 are supplied to a 3 dB hybrid node 57 whose negative output end is terminated by a termination circuit 58 . A composite wave of the outputs of the power amplifiers 55 and 56 is output from the other output terminal of this 3 dB hybrid 57,
It is transmitted via antenna 59.

Although the technique described above is configured using two orthogonal modulators, a transmitter with a simpler configuration can be realized by using a frequency modulator instead of the orthogonal modulators.

However, in the technique described above, the phase difference α between the modulated waves corresponding to the two systems of modulated signals. It is assumed that the phase difference α between the two systems of modulated waves input to the synthesizer matches. Therefore, the phase difference α between these two. , α do not match, the input signal cannot be restored, which has the disadvantage that the out-of-band spectrum deteriorates.

By the way, the initial phases serving as the references of the two independent frequency modulators are different from each other. For this reason, a predetermined phase difference α. Two systems of frequency modulated waves S+(t), 5
When two systems of modulated signals corresponding to t(t) are supplied to these two frequency modulators, a frequency modulated wave S+m(t) is output from both frequency modulators.

The phase difference α of Sz*(t) generally does not match.

Also, even if the initial phases of these two frequency modulators are adjusted to have a predetermined relationship at the beginning,
Considering the accuracy of the frequency modulator, the output of both frequency modulators (frequency modulated wave S+a(t)).

The phase difference α of 5 in(t) is the above-mentioned phase difference α. And - it is difficult to make them lose.

The present invention was created in view of the above points, and provides a transmitting device that amplifies and transmits a signal having an envelope fluctuation with high power efficiency without deteriorating the out-of-band spectrum. The purpose is to

[Means to solve the problem]

FIG. 1 is a block diagram of a transmitting device according to the present invention.

In the figure, the waveform generating means is configured such that a modulation signal is introduced and two
A first modulated signal and a second modulated signal corresponding to each of the frequency modulated waves of the systems and a first phase difference signal indicating a phase difference between the two systems of frequency modulated waves are output.

The first frequency modulation means receives the first modulation signal as input and outputs a first modulation wave corresponding to the first modulation signal.

The correction means corrects the second modulation signal.

The second frequency modulation means receives the output of the correction means as an input, and
A second modulated wave corresponding to this is output.

The combining means adds the two frequency modulated waves output from both frequency modulating means.

The transmitting means transmits the output signal of the combining means.

The phase difference detection means detects the phase difference between the two frequency modulated waves and outputs a second phase difference signal.

The comparison means compares the first phase difference signal and the second phase difference signal to detect a phase error occurring between the two phase differences.

Therefore, the overall configuration is such that the second modulation signal is corrected by the correction means based on the phase error detected by the comparison means.

[For production]

The waveform generation means generates a first modulation signal and a second modulation signal corresponding to two systems of frequency modulated waves based on the introduced modulation signal. Here, the first modulation signal and the second modulation signal are generated so that the input modulation signal is reproduced by combining them.

Further, the waveform generation means generates a first phase difference signal indicating a phase difference between two systems of frequency modulated waves corresponding to the first modulation signal and the second modulation signal, and supplies the first phase difference signal to the comparison means.

The two frequency modulation means each perform frequency modulation based on a corresponding modulation signal, and output two systems of frequency modulated waves. These two systems of constant envelope modulated waves are added by the combining means, and the output signal of this combining means is transmitted by the transmitting means.

Further, the phase difference detection means detects the phase difference between the outputs of the two frequency modulation means, and a second phase difference signal corresponding to this phase difference is generated and supplied to the comparison means.

The comparison means compares the first phase difference signal and the second phase difference signal, and detects a phase error occurring between the two phase differences. Based on this phase error, the correction means
The second modulation signal is corrected so that the phase difference between the two systems of frequency modulated waves and the phase difference between the outputs of the two frequency modulation means have a predetermined relationship.

In the present invention, by generating two systems of frequency modulated waves based on the input modulated signal and then combining them,
A waveform similar to that obtained when a signal obtained by modulating a carrier wave with an input modulation signal is linearly amplified is obtained.

Also, based on the phase error detected by the comparison means,
The second modulation signal is corrected by the correction means. This makes it possible to correct the phase error that occurs between the phase difference between the two systems of frequency modulated waves and the phase difference between the outputs of the two frequency modulation means, so that the signal is accurately restored by the combining means.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows the configuration of a transmitting device in an embodiment of the present invention.

FIG. 4 shows the configuration of a transmitter according to another embodiment to which the present invention is applied.

In FIG. 2, a modulation signal corresponding to a signal wave 5(t) expressed as in equation (1) is introduced into the waveform generation circuit 21.

5(1)=R(t) cos (ωt+φ(t))
(1) Based on this modulation signal, the waveform generation circuit 21 calculates the time differential φ of the phases φ1(t) and φ2(t) of the two systems of frequency modulated waves S+(t) and 5z(t), respectively.
+(1), φ2(t), and generate modulation signals V,(t), Vz(t) proportional to this.

However, these two systems of frequency modulated waves 5t(t), 32(
1) is a 90° hybrid used as a synthesizer.
It is expressed as Equations (2) and (3) in consideration of delay characteristics (described later).

S+(t)=Acos (ωt+φ+(1))
... (2) 5, (t) = Ac o s (
ω +φ2(t)+π/2 )... (3) Also, two systems of frequency modulated waves S+(t), 5t(t)
The respective phases φ+(1), φ2(t) and amplitude A satisfy the relationships shown in equations (4) and (5).

φ(1) = (φg(t) +φ, (t))/2 ・
... (4) R(t) =2Acos C(φ2(
t)-φ, o))/F) In Fig. 3, modulated waves 5(t) and 2
The relationship between the frequency modulated waves 5t(t) and 5t(t) of the system is shown.

In the figure, S z(t) <−q. , is the frequency modulated wave 52(t) delayed by 90@.

These two systems of frequency modulated waves 5t(t) and 5z(
1) by a hybrid having a 90@ delay characteristic, it is possible to reproduce the signal wave 5(t).

The modulated signal V, (t
) is supplied to the voltage controlled oscillator 22, and the modulation signal L(t)
is corrected by the correction circuit 29 and then supplied to the voltage controlled oscillator 23.

Further, the phase difference output circuit 24 outputs these modulation signals v+(
t), the phase difference α between the two systems of frequency modulated waves S+(t) and 5t(t), based on Vz(t). Find this phase difference α. The phase difference signal po(t) corresponding to
Output.

Both type pressure controlled oscillators 22 and 23 perform frequency modulation according to the supplied modulation signals, and generate frequency modulated waves S+
, (t), St, (t) are output and supplied to each of the two input terminals of the 3 dB hybrid 25.

The 3dB hybrid 25 synthesizes the frequency modulated wave S+m(t) introduced into each of the two input terminals and the frequency modulated wave SZ,(t) whose phase is delayed by 90 @, and outputs it as an output signal wave. Output. This is called the 90° delay characteristic of the hybrid.

This output signal wave is transmitted via an antenna 31 connected to one of the output terminals of the 3 dB hybrid node 25. The other end of the 3 dB hybrid 25 is terminated by a termination circuit 30.

Further, in the multiplier 26, this frequency modulated wave 81m (t
) by the frequency modulated wave St, (t), and the multiplier 26
By passing the output through a low-pass filter, a phase difference signal P(t) corresponding to the phase difference α between the two systems of frequency modulated waves S+m(t) and Szm(t) is generated and supplied to the comparison circuit 28. be done.

The comparison circuit 28 calculates the phase difference α. The phase difference signal Pa corresponding to
(t) and a phase difference signal P(t) corresponding to the phase difference α are compared to detect a phase error, and a correction signal corresponding to this phase error is supplied to the correction circuit 24.

The correction circuit 24 corrects the modulation signal Vz(t) according to this correction signal so that the two phase difference signals match.

In this way, the phase error due to the difference in the initial phase of the voltage controlled oscillators 22.23 can be corrected, so that the frequency modulated waves SIm(t), Sz, (t) generated by the voltage controlled oscillators 22.23 The phase difference α is the phase difference α. It is possible to match the .

Since the voltage controlled oscillators 22 and 23 operate with high efficiency in principle, by combining their outputs with the 3 dB hybrid 25, the signal wave corresponding to the introduced modulation signal is generated while keeping the out-of-band spectrum good. 5(t) can be amplified with high power efficiency and transmitted as an output signal.

In addition, the voltage controlled oscillator has a relatively small circuit configuration and is low cost, so it can be used as a transmitting device that transmits a signal wave with a low-cost envelope fluctuation without increasing the circuit configuration of the transmitting device. It can be realized.

In addition, as shown in FIG.
5 and the frequency of the oscillator 34 is added to perform frequency conversion.

The present invention can also be applied to a configuration in which the outputs of the voltage controlled oscillators 22 and 23 are amplified using highly efficient power amplifiers.

〔Effect of the invention〕

As described above, according to the present invention, a signal wave including a signal wave having an envelope fluctuation is decomposed into two systems of frequency modulated waves,
After correcting the phase error caused by the difference in the initial phase of each frequency modulation means, the signals are combined. Thereby, it is possible to configure a transmitting device that can transmit signal waves including signal waves having envelope fluctuations while maintaining a good out-of-band spectrum and with high power efficiency without increasing the circuit scale.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a transmitting device according to the present invention, FIG. 2 is a configuration diagram of a transmitting device according to an embodiment of the present invention, FIG. 3 is an explanatory diagram of frequency modulated waves, and FIG. 4 is another embodiment of the present invention. FIG. 5 is a block diagram of a conventional transmitting device. In the figure, 21.51 is a waveform generation circuit, 22.23 is a voltage controlled oscillator, 24 is a phase difference output circuit, 25.57 is a 3dB hybrid, 26 is a multiplier, 27 is a low-pass filter, 28 is a comparison circuit, and 29 is a 30° 31° 32° 34° 52° 55° is a termination circuit, is an antenna, is a mixer, is an oscillator, is a quadrature modulator, and is a power amplifier. Diagram

Claims (1)

[Claims] (1) A modulated signal is introduced, and a first modulated signal and a second modulated signal corresponding to each of the two systems of frequency modulated waves and a first phase difference signal indicating the phase difference between the two systems of frequency modulated waves are output. a first frequency modulation means for inputting the first modulation signal and outputting a first modulation wave corresponding to the first modulation signal; a correction means for correcting the second modulation signal; and an output of the correction means. As input, the corresponding second
a second frequency modulating means for outputting a modulated wave; a combining means for adding two frequency modulated waves output from both of the frequency modulating means; a transmitting means for transmitting an output signal of the combining means;
a phase difference detection means for detecting a phase difference between two frequency modulated waves and outputting a second phase difference signal; and a comparison means for detecting a phase error occurring between the two, and the second modulation signal is configured to be corrected by the correction means based on the phase error detected by the comparison means. Transmitting device.