JPH08116276A - Transmitter - Google Patents

Abstract

PURPOSE: To emit an output signal of a transmitter use power amplifier from an antenna efficiently. CONSTITUTION: A phase shift circuit 6 comprising a reactance element is provided between a power amplifier 1 and an antenna multicoupler 2. Furthermore, a phase shift circuit 7 comprising a reactance element is provided between a matching circuit 3 and the antenna multicoupler 2. The phase of a load impedance of the phase shifters 6, 7 is adjusted optimizingly so that the output and the efficiency of the power amplifier 1 are maximized with respect to a load of the power amplifier 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitter, and more particularly to improvement of transmission efficiency.

[0002]

2. Description of the Related Art Conventionally, a transmission circuit of a portable telephone device is generally provided with a matching circuit for matching the impedance between the antenna and other circuits as means for efficiently radiating power from the antenna. There is.

Therefore, FIG. 2 is a block diagram of a general transmitter. In FIG. 2, DC power is applied from the battery 5 to the power amplifier 1. The power amplifier 1 power-amplifies the transmission signal and supplies it to the antenna duplexer 2. The antenna duplexer 2 gives the power amplified transmission signal to the matching circuit 3.

The matching circuit 3 applies the transmission signal from the antenna duplexer 3 to the antenna 4 while performing impedance matching with the antenna 4. The antenna 4 radiates the given transmission signal as an electromagnetic wave.

[0005]

However, in response to the recent demand for downsizing and weight saving of portable telephone devices, downsizing of the battery 5 has been promoted. That is, even if the battery capacity becomes small, the radiation characteristic from the antenna 4 cannot be deteriorated. As a result, the power consumption increases only by matching with the matching circuit 3, and even if the maximum output of the power amplifier 1 is obtained, the optimum efficiency cannot be obtained, so that there is a problem that a battery having a small capacity cannot be used. .

In view of the above, it has been demanded to provide a transmitter capable of efficiently radiating and outputting the output signal of the power amplifier for transmission from the antenna.

[0007]

Therefore, the present invention comprises a power amplifier for power-amplifying a signal for transmission, and a matching circuit for giving an output signal from the power amplifier to the antenna by matching with the antenna. In a transmitting device that radiates and outputs from an antenna, the above-mentioned problems are solved by the following configuration.

That is, the line interposed between the power amplifier and the matching circuit is provided with a phase adjusting circuit for adjusting the phase of the load impedance when the matching device is viewed from the power amplifier.

[0009]

According to the present invention, the load of the power amplifier can be reduced by adjusting the phase of the load impedance of the line between the power amplifier and the matching circuit. By reducing the load in this way, the power amplifier can efficiently perform power amplification, can efficiently perform power amplification with low power consumption, and can achieve matching with a matching circuit. Furthermore, the signal from the power amplifier can be fed from the matching circuit to the antenna in the optimum line state.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a transmission device of this embodiment. In FIG. 1, the transmitter is a power amplifier 1,
It is composed of an antenna sharing device 2, a matching circuit 3, an antenna 4, a battery 5, and phase shift circuits 6 and 7. A characteristic of the configuration of this transmitter is that a phase shift circuit 6 including a reactance element is provided between the power amplifier 1 and the antenna duplexer 2. Further, it is also characteristic that a phase shift circuit 7 including a reactance element is provided between the antenna duplexer 2 and the matching circuit 3.

These phase shift circuits 6 and 7 are used for the power amplifier 1.
With respect to the load, the phase of the load impedance can be optimally adjusted so that the output and efficiency of the power amplifier 1 are maximized.

FIG. 3 is a circuit diagram showing the transmitter of FIG. 1 in more detail. In FIG. 3, the transmitter includes a power amplifier 1, an antenna duplexer 2, a matching circuit 3, and an antenna 4.
The phase shift circuits 6 and 7, the directional coupler 8, the stripline line 9, and the reed switch 10. The battery 5 for supplying power to the power amplifier 1 is omitted.

Further, the matching circuit 3 is composed of a capacitor C2 and coils L1 and L2. Capacitor C2
And the coil L2 are connected in parallel. The coil L1 is connected in series to the antenna 4.

A directional coupler 8 is connected to the output of the power amplifier 1 to which the transmission signal is applied, and a phase shift circuit 6 is connected to optimally adjust the phase of the load impedance. The directional coupler 8 is for taking out a part of the transmission signal and separating the transmission signal and the reception signal. The output of the directional coupler 8 is given to the antenna duplexer 2.

The aerial duplexer 2 connects a system from the output of the power amplifier 1 to the antenna 4 for a transmission signal and for a reception signal between a receiving circuit (not shown) and the antenna 4. It operates so as to connect the system. Therefore,
At the time of transmission, the transmission signal from the directional coupler 8 is given to the stripline line 9 and the phase shift circuit 7.

The stripline line 9 secures a predetermined inductance and a distributed capacitance with respect to a high frequency signal to adjust the impedance, and is provided between the antenna duplexer 2 and the matching circuit 3 via the reed switch 10. It is connected in series. The stripline line is, for example, a copper printed pattern having a width of about 0.2 mm and a length of about 25 mm and a characteristic impedance of 50 mm.
It is about Ω.

In particular, the phase shift circuit 7 connected so as to terminate at the output of the antenna duplexer 2 is seen from the power amplifier 1 at the output side of the antenna duplexer 2 in addition to the above-mentioned phase shift circuit 6. Connected to optimally adjust the phase of the load impedance.

The transmission signal whose impedance has been adjusted by the stripline line 9 is given to the capacitor C2 and the coils L1 and L2 of the matching circuit 3 via the reed switch 10. The capacitor C2 of the matching circuit 3 is the coil L2.
Are connected in parallel, and the coil L1 connected in series to the antenna 4 operates so as to achieve impedance matching with the antenna 4.

The matching circuit 3 applies a transmission signal whose impedance is matched to the antenna 4 and causes it to emit a radio wave. With such a configuration, it is possible to efficiently radiate radio waves by adjusting the phase of the load impedance by the phase shift circuits 6 and 7.

(Test / Evaluation of Transmitting Device): Next, the above-mentioned transmitting device was tested and evaluated. Therefore, FIG. 4 shows a test circuit diagram (part 1) of the transmitter used for the test. In FIG. 4, a point different from FIG. 3 described above is that the phase shift circuit 6 includes a capacitor C0.
Be connected. Further, as the phase shift circuit 7, the coil LDup out is connected to the output side of the directional coupler 8.

((Operation of Capacitor C0)): FIG.
(A), (b) is a graph showing the relationship of the consumption current of a transmitter with respect to the change of the capacitor C0. Capacitor C
0 capacitance is 0.3pF, 0.5pF, 0.8pF, 1p
f and the characteristics without the capacitor C0.
Further, the curve indicated by ♦ is the characteristic at the frequency f1 = 898 MHz. The curve marked with “black squares” is the characteristic at the frequency f2 = 915 MHz. The curve indicated by ▴ is the characteristic at the frequency f3 = 920 MHz.
The curve indicated by X is the characteristic at the frequency f4 = 925 MHz. Finally, the curve marked with a circle is the characteristic of the average value.

The graph of FIG. 5A shows a long antenna,
That is, it is a characteristic diagram when the antenna is extended. The graph of FIG. 5B is a characteristic diagram when the short antenna, that is, the antenna is stored. From these two graphs, it was found that the larger the value of the capacitor C0, the smaller the current consumption.

((Operation of coil LDup out)):
FIGS. 6A and 6B are graphs showing the relationship of the current consumption of the transmission device with respect to the change in the coil LDup out. The inductance of the coil LDup out is 20n
H. The characteristics are shown at 30 nH, 40 nH, and 50 nH. Furthermore, the curve marked with ◆ is frequency f1 = 898M
It is a characteristic in Hz. The curve marked with “black squares” is the characteristic at the frequency f2 = 915 MHz. The curve indicated by ▴ is the characteristic at the frequency f3 = 920 MHz. The curve indicated by X is the characteristic at the frequency f4 = 925 MHz. Finally, the curve marked with * is the characteristic of the average value.

The graph of FIG. 6A shows a long antenna,
That is, it is a characteristic diagram when the antenna is extended. It can be seen from this figure that although the frequency f1 is large overall, the change in the inductance of the coil LDup out has little effect on the current consumption. The graph of FIG. 6B is a characteristic diagram when the short antenna, that is, the antenna is stored. From this figure, the change in the inductance of the coil LDup out has an influence of about 50 mA depending on each frequency, and the smaller the inductance, the smaller the current consumption.

FIGS. 7A and 7B show the coil LDup o.
It is a graph showing the relationship of the radiation power of a transmitter with respect to the change of ut. The inductance of the coil LDup out represents the characteristics at 20 nH, 30 nH, 40 nH, and 50 nH. Furthermore, the curve marked with ◆ is frequency f1.
= 898 MHz. The curve marked with “black squares” is the characteristic at the frequency f3 = 920 MHz. The curve marked with ▴ is the characteristic at frequency f4 = 925 MHz. The curve marked with a cross is a characteristic of the average value.

The graph of FIG. 7A shows a long antenna,
That is, it is a characteristic diagram when the antenna is extended. From this figure, although the change is large at the frequency f1 as a whole, the change in the inductance of the coil LDup out affects the radiated power of about 1 dB at the frequencies f3, f4 and the inductances 20 to 40 nH. The graph of FIG. 7B is a characteristic diagram when the short antenna, that is, the antenna is stored. From this figure,
The change in the inductance of the coil LDup out is 1 at the frequencies f3 and f4 and the inductance of 20 to 40 nH.
It has an influence of about dB.

FIG. 8 is a diagram showing the relationship between the load phase and the current consumption of the power amplifier 1. In FIG. 8, phase-3
Current consumption 540-490 mA for 0 ° -250 ° is shown. In the phase −80 ° to −50 °, the current consumption is about 495 mA, which is a good value.

FIG. 9 is a diagram showing the relationship between the load phase and the radiated power for the power amplifier 1 of the embodiment. In this FIG.
Radiated power for phase -30 ° to 250 ° -13.5 ~
-14.9 dBm is shown. Phase -80 ° to -5
At 0 °, the radiated power is maximum at -13.5 dBm, and a good value is obtained.

Next, evaluation was performed using the test circuit (No. 2) of the transmitter shown in FIG. 10, the difference from the circuit of FIG. 3 described above is that the directional coupler 8 is connected to the output of the power amplifier 1, but the phase shift circuit is not connected. Further, instead of the antenna duplexer 2, the bandpass filter 11 is connected to the output of the directional coupler 8. Furthermore, a coil having an inductance of 30 nH is connected as a load to the output of the bandpass filter 11 as a phase shift circuit. The capacitor C2 of the matching circuit 3 was set to 1 pF.

FIG. 11 is a relationship diagram between the load phase and the current consumption in the test circuit of FIG. In this FIG.
The mark ● indicates the characteristic when the antenna is long, that is, the antenna 4 is extended, and the mark ○ indicates the characteristic when the short antenna is stored, that is, the characteristic. This characteristic has almost the same inclination as that in FIG.

FIG. 12 is a relationship diagram between the load phase and the radiated power in the test circuit of FIG. In FIG. 12,
The mark ● indicates the characteristic when the antenna is long, that is, the antenna 4 is extended, and the mark ○ indicates the characteristic when the short antenna is stored, that is, the characteristic. This characteristic has almost the same inclination as that in FIG. 9 described above.

FIG. 13 is a characteristic diagram of current consumption for the coil L2 of the matching circuit when the antenna of the test circuit of FIG. 10 is expanded. In FIG. 13, when the antenna is extended (long antenna), ● indicates a characteristic diagram when L1 = 15 nH, × indicates a characteristic diagram when L1 = 18 nH, and ▲ indicates a characteristic diagram when L1 = 21 nH. Characteristic diagram, ○ indicates L1 = 2
It is a characteristic view in case of 3nH. L2 was set to 7 to 11 nH.

FIG. 14 is a characteristic diagram of current consumption for the coil L2 of the matching circuit when the antenna of the test circuit of FIG. 10 is stored. In FIG. 13, when the antenna is stored (short antenna), the ● mark shows the characteristic diagram when L1 = 15 nH, the × mark shows the characteristic diagram when L1 = 18 nH, ▲
The mark shows the characteristic diagram when L1 = 21 nH, and the mark shows L1 =
It is a characteristic view in case of 23 nH. L2 was set to 7 to 11 nH.

According to FIGS. 13 and 14, it is preferable that L1 = 15 to 23 nH and L2 = 7 to 9 nH in order that the current consumption becomes 580 mA or less when the antenna is extended.

FIG. 15 is a characteristic diagram of radiation power to the coil L2 of the matching circuit when the antenna of the test circuit of FIG. 10 is expanded. In FIG. 15, when the antenna is extended (long antenna), ● indicates a characteristic diagram when L1 = 15nH, × indicates a characteristic diagram when L1 = 18nH, and ▲ indicates a L1 = 21nH characteristic diagram. Characteristic diagram, ○ indicates L1 = 2
It is a characteristic view in case of 3nH. L2 was set to 7 to 11 nH.

FIG. 16 is a characteristic diagram of the radiated power to the coil L2 of the matching circuit when the antenna of the test circuit of FIG. 10 is stored. In FIG. 16, when the antenna is stored (short antenna), ● indicates a characteristic diagram when L1 = 15 nH, × indicates a characteristic diagram when L1 = 18 nH, ▲
The mark shows the characteristic diagram when L1 = 21 nH, and the mark shows L1 =
It is a characteristic view in case of 23 nH. L2 was set to 7 to 11 nH.

According to FIG. 15 and FIG. 16 as described above, L1 = 15 to 23 nH, L in order to reduce the current consumption to 580 mA or less when the antenna is extended (see FIGS. 13 and 14).
2 = 7-9 nH is preferable, and the radiated power at this time is at least -14.8 dBm.

Therefore, the load phase of the power amplifier 1 satisfying the radiated power of -14.8 dBm or more is shown in FIG.
Since the characteristics of FIG. 12 are similar to those of FIGS. 8 and 9, the maximum output and the optimum efficiency are obtained in the load phase range of −80 ° to −50 ° from FIGS. 8 and 9.

As described above, a phase shift circuit using a reactance element is used on the output side of the power amplifier 1 and the antenna connection side of the antenna duplexer 2, and the matching circuit 3 is used to induce the load phase of the power amplifier 1. The property is to change the property or capacity.

(Effect of Embodiment) According to the transmitter of the above embodiments, the capacitor C0 is used as the phase shift circuit 6 and the coil LDup out is used as the phase shift circuit 7, and the circuit constant of the matching circuit 3 is optimally selected. Thus, the required load phase can be set arbitrarily.

That is, by changing the load phase by using a reactance element or the like in the phase shift circuits 6 and 7, it is possible to give an optimum load phase to the output of the power amplifier 1, and thereby to the power amplifier 1. Maximum output can be achieved with optimum efficiency.

By improving the transmission efficiency, the power consumption can be reduced, the required capacity for the battery 5 can be reduced, and a small battery can be used.

(Other Embodiments) (1) In the above embodiments, the matching circuit 3 has the circuit configuration shown in FIG. 3, but in addition to this, for example, the circuits shown in FIGS. It can also be a matching circuit having a configuration. The matching circuit of FIG. 17 is based on the coil L1 and the coil L2. The matching circuit of FIG. 18 is a T-type circuit including the coils L1 to L3.

(2) Further, the phase shift circuits 6 and 7 can be constituted by a series circuit or a parallel circuit including resistors, coils, capacitors and the like. It is also preferable to use a dielectric element to obtain the required inductance.

(3) Further, in the case of a mobile phone device, the antenna 4 is considered to be capable of improving operability and downsizing by using a retractable antenna.

(4) Furthermore, the matching circuit 3 may switch the matching state between when the antenna is extended and when it is stored, or may be provided with two types of matching circuits.

(5) Further, although the above embodiment has been described as a transmitting apparatus, since the antenna duplexer 2 is provided, the antenna 4 is used for both transmission and reception, and a receiving circuit is further provided to realize a transmission / reception apparatus. You can also

[0048]

As described above, the transmitter of the present invention is
Since the line interposed between the power amplifier and the matching circuit is equipped with a phase adjusting circuit that adjusts the phase of the load impedance when the matching device side is viewed from the power amplifier, the transmission signal can be efficiently radiated and output. It is possible.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a transmission device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional transmission device.

FIG. 3 is a detailed functional configuration diagram of the transmission device according to the embodiment.

FIG. 4 is an evaluation test circuit diagram (part 1) of the transmitter of the embodiment.
Is.

FIG. 5 is a characteristic diagram showing a relationship between load capacitance and current consumption for the power amplifier of the embodiment.

FIG. 6 is a load coil LDu for the power amplifier of the embodiment.
It is a characteristic view showing the relationship between the inductance of pout and consumption current.

FIG. 7 is a load coil LDu for the power amplifier of the embodiment.
It is a characteristic view showing the relationship between the inductance of pout and radiation power.

FIG. 8 is a relationship diagram between a load phase and a consumption current for the power amplifier of the embodiment.

FIG. 9 is a diagram showing a relationship between load phase and radiated power for the power amplifier of the embodiment.

FIG. 10 is an evaluation test circuit diagram (No. 2) of the transmitter of the embodiment.

FIG. 11 is a relationship diagram between the load phase and the consumed current according to the evaluation test circuit diagram (Part 2) of the example.

FIG. 12 is a relationship diagram between a load phase and radiation power according to an evaluation test circuit diagram (Part 2) of the example.

FIG. 13 is a characteristic diagram of current consumption with respect to the coil L2 of the matching circuit at the time of antenna extension in the evaluation test circuit diagram (part 2) of the example.

FIG. 14 is a characteristic diagram of current consumption with respect to the coil L2 of the matching circuit when the antenna is housed in the evaluation test circuit diagram (part 2) of the example.

FIG. 15 is a characteristic diagram of radiation power to the coil L2 of the matching circuit at the time of antenna extension in the evaluation test circuit diagram (part 2) of the example.

FIG. 16 is a characteristic diagram of radiation power to the coil L2 of the matching circuit when the antenna is housed in the evaluation test circuit diagram (part 2) of the example.

FIG. 17 is a circuit diagram (1) of a matching circuit according to another embodiment.

FIG. 18 is a circuit diagram (No. 2) of a matching circuit according to another embodiment.

[Explanation of symbols]

1 ... Power amplifier, 2 ... Antenna duplexer, 3 ... Matching circuit, 4
... antenna, 5 ... battery, 6, 7 ... phase shift circuit, 8 ... directional coupler, 9 ... stripline line, 10 ... reed switch.

Claims (1)

[Claims] 1. A transmission device comprising a power amplifier for power-amplifying a signal for transmission, and a matching circuit for matching the output signal from the power amplifier with the antenna and supplying the antenna to the antenna, wherein the transmitter radiates and outputs from the antenna. A transmission device comprising a phase adjusting circuit for adjusting a phase of a load impedance when a matching device side is viewed from the power amplifier, on a line interposed between the power amplifier and the matching circuit.