JP2000114804A - Antenna sharing device and communication equipment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a miniaturized antenna sharing device and communication equipment device capable of efficiently removing the higher harmonic waves in a transmission signal generated by a transmission/reception changeover switch. SOLUTION: This antenna device is provided with a frequency variable filter 13 for switching transmission and reception bands through voltage controlled PIN diodes D1-D3 and a transmission/reception changeover switch 14 connected to an input/output terminal at one end of this frequency variable filter 13. The frequency variable filter 13 couples three stages of resonators 24-26 through coupling capacitors C4 and C5. An input/output terminal P1 of the frequency variable filter 13 is electrically connected through a π-shaped LC circuit (low-pass filter) composed of a coupling coil L5 and capacitors C6 and C7 to the resonator 24. An input/output terminal P2 is electrically connected through a π-shaped LC circuit (low-pass filter) composed of a coupling coil L6 and capacitors C8 and C9 to the resonator 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna duplexer and a communication device used in, for example, a microwave band.

[0002]

2. Description of the Related Art One of mobile telephone systems is a time-division multiple access system (time-division multiple access system).
le access system). FIG.
FIG. 3 is an electric circuit block diagram of an RF transmitting / receiving part of the mobile phone 1 using this system. 10, 2 is an antenna element, 4 is a transmission / reception switch, 5 is a transmission filter, 6 is a reception filter, 7 is a transmission circuit, and 8 is a reception circuit. The transmission / reception switch 4 is often formed of a PIN diode or a GaAs switch IC or the like.

[0003]

However, FIG.
1 requires a transmission filter 5 and a reception filter 6, which hinders miniaturization and cost reduction of the mobile phone 1. Since the transmission / reception changeover switch 4 composed of a PIN diode or the like has nonlinearity, a high-output transmission signal
Thus, there is a problem that unnecessary harmonics such as a second harmonic and a third harmonic of a transmission signal are generated. For this reason, a low-pass filter or the like is externally attached to the antenna element 2 or the PIN
In the case of the transmission / reception changeover switch 4 composed of a diode, measures such as increasing the current consumption of the PIN diode have been taken. However, the former measure is mobile phone 1
The latter measure leads to battery consumption.

An object of the present invention is to provide a small antenna duplexer and a communication device capable of efficiently removing harmonics of a transmission signal generated by a transmission / reception switch.

[0005]

In order to achieve the above object, an antenna duplexer according to the present invention comprises:
And a second transmission / reception switch connected to an input / output terminal at one end of the variable frequency filter. Features. More specifically, the variable frequency filter includes a low-pass filter. As the reactance element,
A PIN diode, a field effect transistor, or the like is used. As the transmission / reception changeover switch, a switch composed of a PIN diode, a GaAs switch IC, or the like is used. As the resonator of the frequency variable filter, a dielectric resonator or the like is used.

[0006] With the above configuration, one frequency variable filter can be used as both a transmission filter and a reception filter, and the antenna duplexer can be reduced in size. Further, since the variable frequency filter includes a low-pass filter, unnecessary harmonics generated by distortion of the transmission signal are removed by the variable frequency filter.

In the antenna duplexer according to the present invention, each of the first and second bands of the variable frequency filter is divided into a plurality of frequency regions, and a reactance element is voltage-controlled to provide one of the plurality of frequency regions. Is selected. As a result, the interval (isolation) between the transmission band and the excess reception band of the duplexer can be widened, and the filter characteristics can be further improved.

Further, the communication device according to the present invention is provided with any one of the antenna duplexers having the above-described features, so that the size can be reduced and unnecessary harmonics generated by distortion of the transmission signal can be achieved. Can be removed.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of an antenna duplexer and a communication device according to the present invention will be described with reference to the accompanying drawings.

[First Embodiment, FIGS. 1 to 6] FIG. 1 is an electric circuit block diagram of an RF transmitting / receiving portion of a mobile phone 11 as a communication device. In FIG. 1, 12 is an antenna element, 15 is an antenna duplexer, 17 is a transmitting circuit, and 18 is a receiving circuit. The antenna duplexer 15 includes a variable frequency filter 13 and a transmission / reception switch 14.

As shown in FIG. 2, the variable frequency filter 13 includes resonators 24, 25, and 26 each having a coupling capacitor C.
4, and C5 are connected in three steps. The input / output terminal P1 of the variable frequency filter 13 is electrically connected to the resonator 24 via a π-type LC circuit (low-pass filter) composed of a coupling coil L5 and capacitors C6 and C7. Similarly, the input / output terminal P2 is electrically connected to the resonator 26 via a π-type LC circuit (low-pass filter) composed of a coupling coil L6 and capacitors C8 and C9. As described above, the frequency variable filter 13 includes the low-pass filter.

A PIN diode D1, which is a reactance element, is connected to one end of the resonator 24 via a band variable capacitor C1 with the cathode grounded.
Are electrically connected in parallel. Similarly, one end of the resonator 25 is connected via a band-variable capacitor C2 to
With the PIN diode D2 grounded at the cathode,
It is electrically connected to the resonator 25 in parallel. A PIN diode D3 is electrically connected to one end of the resonator 26 in parallel with the resonator 26 with a cathode grounded via a band variable capacitor C3.

The voltage control terminal CONT1 is connected to a control voltage supply resistor R1, a capacitor C10 and a choke coil L1.
, Is electrically connected to an intermediate connection point between the anode of the PIN diode D1 and the band variable capacitor C1. Similarly, the voltage control terminal CONT1 is connected to the control voltage supply resistor R1 and the capacitor C10 and the choke coil L2.
, And electrically connected to an intermediate connection point between the anode of the PIN diode D2 and the band variable capacitor C2, and further connected to the anode of the PIN diode D3 and the band via the control voltage supply resistor R1 and the capacitor C10 and the choke coil L3. It is electrically connected to the intermediate connection point of the variable capacitor C3.

As the resonators 24-26, for example, as shown in FIGS. 3 and 4, a λ / 4 dielectric resonator is used. FIG. 3 shows the resonator 24 as a representative example. The dielectric resonators 24 to 26 include a rectangular parallelepiped dielectric block 31 formed of a high dielectric constant material such as TiO ₂ ceramic, and resonator holes 32 a, 32 b, and 32 c provided in the dielectric block 31, respectively. An outer conductor 37 provided on the outer peripheral surface of the dielectric block 31;
Inner conductors 38 provided on the inner peripheral surfaces of 2b and 32c, respectively.
It is composed of The outer conductor 37 is a dielectric block 3
One of the open end faces 31a (hereinafter, referred to as open side end face 31a) is electrically opened (separated) from the inner conductor 38, and the other open end face 31b (hereinafter, referred to as short-circuit side end face 31b) has an inner end. The conductor 38 is electrically short-circuited (conductive). The dielectric resonator 24 includes a band variable capacitor C1 and a PIN diode D1 on the open side end face 31a.
Are electrically connected in a state where one end of the band variable capacitor C1 is connected to the inner conductor 38 and the cathode of the PIN diode D1 is connected to the ground, and the outer conductor 37 is connected to the ground at the short-circuit side end face 31b. Have been. FIG. 4 is a perspective view of the frequency variable filter 13 in which each component is mounted on the circuit board 40. Circuit board 4
The circuit pattern on 0 is not shown.

As shown in FIG. 5, the transmission / reception changeover switch 14 is constituted by PIN diodes D4 and D5. The cathode of the PIN diode D4 is electrically connected to the antenna terminal 14a via the coupling capacitor C11, and is electrically connected to the reception terminal 14c via the phase shifter 42 and the coupling capacitor C13. The anode of the PIN diode D4 is electrically connected to the transmission terminal 14b via the coupling capacitor C12.

The voltage control terminal CONT1, the control voltage supply resistor R1 and the capacitor C10 are shared with the variable frequency filter 13. Voltage control terminal CONT1
Is electrically connected to an intermediate connection point between the anode of the PIN diode D4 and the capacitor C12 via the control voltage supply resistor R1, the capacitor C10, and the phase shifter 41. Further, the PIN diode D5 has a cathode grounded and an anode electrically connected to an intermediate connection point between the phase shifter 42 and the capacitor C13. Here, the phase shifter 41,
Reference numeral 42 is, for example, a strip line.

Next, the operation and effect of the antenna duplexer 15 having the above configuration will be described. The antenna duplexer 15 outputs a transmission signal input from the transmission circuit 17 to the antenna element 12 and outputs a reception signal input from the antenna element 12 to the reception circuit 18.

The pass frequency of the frequency variable filter 13 is determined by a resonance system composed of the band variable capacitor C1 and the resonator 24, a band variable capacitor C2 and the resonator 25.
, And the resonance frequency of the resonance system including the variable-band capacitor C3 and the resonator 26. Then, when operating the transmission circuit 17, a positive voltage is applied as a control voltage to the voltage control terminal CONT1, and the PIN diodes D1 to D3 are turned on. Thereby, the band variable capacitors C1 to C3
Are grounded via the PIN diodes D1 to D3, respectively, and the frequency of the pass band of the filter 13 decreases. The low pass band of this frequency is assigned to the transmission signal (see FIG. 6).

On the other hand, when a positive voltage is applied to the voltage control terminal CONT1, the transmission / reception changeover switch 14 sets the PI
N diodes D4 and D5 are turned on. Therefore, the transmission terminal 14b is connected to the capacitor C12 and the PIN diode D
4, connected to the antenna terminal 14a via the capacitor C11, and an intermediate connection point between the phase shifter 42 and the capacitor C13 is grounded via the PIN diode D5. That is, the receiving terminal 14c is electrically separated from the antenna terminal 14a and the transmitting terminal 14b by the capacitor C13, and the switch 14 is switched to the transmitting side. As a result, the transmission signal output from the transmission circuit 17 is sent to the antenna element 12 via the switch 14 and the variable frequency filter 13. The sneaking of the transmission signal from the transmission circuit 17 to the reception circuit 18 is prevented by the isolation of the switch 14.

Conversely, when operating the receiving circuit 18,
A negative voltage is applied to the voltage control terminal CONT1 as a control voltage to turn off the PIN diodes D1 to D3. Instead of applying a negative voltage, the voltage control terminal C
The control circuit for supplying the control voltage to the ONT 1
0KΩ or higher impedance and voltage control terminal CO
By preventing the voltage from being applied to NT1, the control voltage may be set to 0V and the PIN diodes D1 to D3 may be turned off. Thereby, the band variable capacitor C
1 to C3 are in an open state, and the frequency of the pass band increases. The pass band having the higher frequency is assigned to the received signal (see FIG. 6).

On the other hand, when a negative voltage is applied to the voltage control terminal CONT1, the transmission / reception changeover switch 14 sets the PI
N diodes D4 and D5 are turned off. Therefore,
The antenna terminal 14a is connected to the capacitor C11 and the phase shifter 4
2. Connected to the receiving terminal 14c via the capacitor C13. That is, the transmission terminal 14b is connected to the PIN diode D
4, the switch 14 is electrically separated from the antenna terminal 14a and the reception terminal 14c, and the switch 14 is switched to the reception side. As a result, the received signal input from the antenna element 12 passes through the frequency variable filter 13 and the switch 14,
The signal is sent to the receiving circuit 18.

As described above, the filter 13 can have two different pass bands by grounding and opening the band variable capacitors C1 to C3 by voltage control. That is, one frequency variable filter 13 can be used as both a transmission filter and a reception filter, and the antenna duplexer 15 can be reduced in size.

Further, in this antenna duplexer 15, the variable frequency filter 13 is a low-pass filter composed of a coupling coil L5 and capacitors C6 and C7, and a low-pass filter composed of a coupling coil L6 and capacitors C8 and C9. Including filters. Thus, unnecessary harmonics such as the second harmonic and the third harmonic of the transmission signal generated by the transmission / reception switch 14 can be efficiently attenuated by the low-pass filter. As a result, problems such as an increase in the size of the device and an increase in current consumption due to the external attachment of the conventional low-pass filter can be solved.

[Second Embodiment, FIG. 7] FIG. 7 shows a variable frequency filter 13A of an antenna duplexer according to a second embodiment. This variable frequency filter 13A includes:
The frequency variable filter 13 of the first embodiment is the same as the one using the field effect transistors 51, 52 and 53 instead of the PIN diodes D1, D2 and D3. However, only on the input / output terminal P1 side,
A low-pass filter (specifically, a low-pass filter including a coupling coil L5 and capacitors C6 and C7) is provided. With this low-pass filter, unnecessary harmonics of the transmission signal generated by the transmission / reception switch 14 can be attenuated. The input / output terminal P2 is electrically connected to the resonator 26 via the coupling capacitor C21. Variable frequency filter 13 having the above configuration
The antenna duplexer provided with A has the same effect as the antenna duplexer 15 of the first embodiment.

[Third Embodiment, FIGS. 8 and 9] The antenna duplexer of the third embodiment divides a transmission band (or a reception band) into a plurality of frequency regions (in the third embodiment, the frequency band is divided into two frequency regions). In this case, any one of the divided frequency ranges can be selected. The antenna duplexer needs to sharply attenuate the frequency regions near the transmission band and the reception band to ensure isolation between the transmission band and the reception band. For this reason,
Usually, measures such as sacrificing insertion loss or increasing the number of coupling stages of the resonator have been taken. The antenna duplexer according to the third embodiment can increase the interval (isolation) between the transmission band and the reception band by selecting one from each of the frequency regions separated from the transmission band and the reception band. As a result, there is no need to sharply attenuate the frequency regions near the transmission band and the reception band, and the filter characteristics of the antenna duplexer can be improved.

FIG. 8 shows a variable frequency filter 61 of the antenna duplexer according to the third embodiment. In the frequency variable filter 61, the resonators 62 and 63 are coupled in two stages via a coupling capacitor C37. The input / output terminal P1 of the variable frequency filter 61 is electrically connected to the resonator 62 via a π-type LC circuit (low-pass filter) composed of a coupling coil L16 and capacitors C38 and C39. Similarly, the input / output terminal P2 is connected to the coupling coil L
17 and a π-type L composed of capacitors C40 and C41
It is electrically connected to the resonator 63 via a C circuit (low-pass filter).

A PIN is connected to one end of the resonator 62 via capacitors C31, C32, and C33 for changing the band, respectively.
Diodes D10, D11 and D12 are electrically connected in parallel to the resonator 62 with the cathode grounded. Similarly, one end of the resonator 63 is connected to the PI through a band variable capacitor C34, C35, C36, respectively.
N diodes D13, D14 and D15 are electrically connected in parallel to the resonator 63 with the cathode grounded.

The voltage control terminal CONT1 is connected to a control voltage supply resistor R2, a capacitor C42 and a choke coil L1.
0, is electrically connected to an intermediate connection point between the anode of the PIN diode D10 and the band variable capacitor C31, and is connected to the PIN diode D13 via the control voltage supply resistor R2 and the capacitor C42 and the choke coil L13.
Is electrically connected to an intermediate connection point between the anode and the band variable capacitor C34. The voltage control terminal CONT2 is
It is electrically connected to the intermediate connection point between the anode of the PIN diode D11 and the band variable capacitor C32 through the control voltage supply resistor R3 and the capacitor C43 and the choke coil L11.
43 and an intermediate connection point between the anode of the PIN diode D14 and the band variable capacitor C35 via the choke coil L14. Voltage control terminal CONT
3 is a PIN diode D12 via a control voltage supply resistor R4 and a capacitor C44 and a choke coil L12.
The anode of the PIN diode D15 and the band-variable capacitor C36 are electrically connected to an intermediate connection point between the anode of the PIN diode D15 and the control voltage supply resistor R4 and the capacitor C44 and the choke coil L15.
Is electrically connected to the intermediate connection point.

The frequency variable filter 61 having the above-described structure and the transmission / reception switch 14 shown in FIG.
The operation and effect of the antenna duplexer having the following will be described.

The passing frequency of the variable frequency filter 61 is controlled by a resonance system composed of the band variable capacitors C31, C32, C33 and the resonator 62, and by the band variable capacitors C34, C35, C36 and the resonator 63. It is determined by the respective resonance frequency of the resonance system configured. When the transmission circuit 17 shown in FIG. 1 is operated, a positive voltage is applied to each of the voltage control terminals CONT1, CONT2, and CONT3, and the PIN diodes D10 to D10 are applied.
15 is turned on. As a result, the band variable capacitors C31 to C36 are respectively connected to the PIN diodes D10
To D15, and the frequency of the pass band of the filter 61 becomes the lowest. The lowest pass band of this frequency is assigned to the transmission signal (see the solid line 71a in FIG. 9). Further, a positive voltage is applied to the voltage control terminals CONT1 and CONT2 to apply PIN diodes D10, D11, D13, D
14 is turned on, and a negative voltage is applied to the voltage control terminal CONT3 to turn off the PIN diodes D12 and D15. Thereby, the band variable capacitors C31, C32, C34, and C35 are grounded, respectively.
Since the band variable capacitors C33 and C36 are open, the frequency of the pass band of the filter 61 becomes the second lowest. This second lowest passband is also assigned to the transmitted signal (see dotted line 71b in FIG. 9).

On the other hand, when a positive voltage is applied to the voltage control terminals CONT1, CONT2, and CONT3, and when the voltage control terminal CONT
1, a positive voltage is applied to CONT2 and CONT
3, when a negative voltage is applied, the PIN diode D
4, D5 are set to the ON state. As a result, the switch 14 switches to the transmission side, and the transmission circuit 17
Is transmitted to the antenna element 12 via the switch 14 and the variable frequency filter 61.

Conversely, when operating the receiving circuit 18 shown in FIG. 1, a negative voltage is applied to each of the voltage control terminals CONT1, CONT2 and CONT3 to turn off the PIN diodes D10 to D15. Thereby,
The band variable capacitors C31 to C36 are in an open state, and the frequency of the pass band of the filter 61 is the highest.
The highest passband of this frequency is assigned to the received signal (see the solid line 71d in FIG. 9). Further, the voltage control terminal CO
A negative voltage is applied to NT1 and OCNT2 to turn off the PIN diodes D10, D11, D13 and D14, and a positive voltage is applied to the voltage control terminal CONT3 to turn on the PIN diodes D12 and D15.
Thereby, the band variable capacitors C31, C32, C
34 and C35 are respectively opened, the band variable capacitors C33 and C36 are grounded, and the frequency of the pass band of the filter 61 becomes the second height. This second highest passband is also assigned to the transmitted signal (dotted line 7 in FIG. 9).
1c).

On the other hand, the transmission / reception changeover switch 14 operates when a negative voltage is applied to the voltage control terminals CONT1, CONT2 and CONT3, and when the voltage control terminal CONT
1, a negative voltage is applied to CONT2, and CONT
3, when a positive voltage is applied, the PIN diode D
4, D5 are set to the OFF state. As a result, the switch 14 is switched to the receiving side, and the received signal from the antenna element 12 is
The signal is sent to the receiving circuit 18 via the switch 1.

As described above, the filter 61 can have a transmission band and a reception band by grounding and opening each of the band variable capacitors C31 to C36 by voltage control, and can have a transmission band and a reception band. The pass frequency can be varied in two steps even within the band, and the interval (isolation) between the transmission band and the reception band
Can be expanded. Further, in the antenna duplexer according to the third embodiment, the variable frequency filter 61 includes a low-pass filter including a coupling coil L16 and capacitors C38 and C39, a coupling coil L17 and a capacitor C17.
40 and a low-pass filter constituted by C41. Thus, unnecessary harmonics such as the second harmonic and the third harmonic of the transmission signal generated by the transmission / reception switch 14 can be efficiently attenuated by the low-pass filter. As a result, problems such as an increase in the size of the device and an increase in current consumption due to the external attachment of the conventional low-pass filter can be solved.

[Other Embodiments] The antenna duplexer and the communication device according to the present invention are not limited to the above-described embodiment, but can be variously modified within the scope of the gist.

The antenna duplexer of the above embodiment is formed of a single dielectric block, but is not necessarily limited to this. For example, a dielectric block divided for each resonator hole may be connected. Further, the resonator hole may be a step-type hole having a large-diameter hole and a small-diameter hole communicating with the large-diameter hole, in addition to the straight type having a constant hole diameter. In addition, the resonator of the frequency variable filter may be a microstrip line or an LC resonance circuit combining an inductor element and a capacitor element, in addition to the dielectric resonator.
Further, in the above embodiment, the transmission / reception changeover switch is configured by combining PIN diodes as shown in FIG. 5, but the present invention is not limited to this, and a well-known GaAs switch IC may be used.

[0037]

As is apparent from the above description, according to the present invention, a variable frequency filter in which the first band and the second band are switched by a voltage-controllable reactance element, By providing a transmission / reception switch connected to the input / output terminal at one end, a single frequency variable filter can be used as both a transmission filter and a reception filter, and the antenna duplexer can be reduced in size. it can. Further, since the variable frequency filter includes a low-pass filter, unnecessary harmonics generated by distortion of the transmission signal can be removed by the variable frequency filter. As a result,
Problems such as an increase in the size of the device and an increase in current consumption due to the external attachment of the conventional low-pass filter can be solved.

Further, the first and second bands of the frequency variable filter are divided into a plurality of frequency regions, respectively, and the reactance element is voltage-controlled to select one of the plurality of frequency regions. , The interval (isolation) between the transmission band and the reception excess band can be widened, and the filter characteristics are further improved.

[Brief description of the drawings]

FIG. 1 is an electric circuit block diagram showing an embodiment of a communication device according to the present invention.

FIG. 2 is an electric circuit diagram showing a variable frequency filter used in the antenna duplexer shown in FIG.

FIG. 3 is a sectional view showing an example of a resonator used in the frequency variable filter shown in FIG. 2;

FIG. 4 is a perspective view showing a mounting structure of the frequency variable filter shown in FIG. 2;

FIG. 5 is an electric circuit diagram showing a transmission / reception changeover switch used in the antenna duplexer shown in FIG. 1;

FIG. 6 is a graph showing filter characteristics of the duplexer shown in FIG. 1;

FIG. 7 is an electric circuit diagram showing a variable frequency filter used in another antenna duplexer according to the present invention.

FIG. 8 is an electric circuit diagram showing a variable frequency filter used in yet another antenna duplexer according to the present invention.

FIG. 9 is a graph showing filter characteristics of the duplexer shown in FIG. 8;

FIG. 10 is an electric circuit block diagram showing a conventional communication device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Mobile telephone (communication apparatus) 12 ... Antenna element 13, 13A ... Variable frequency filter 14 ... Transmission / reception changeover switch 15 ... Antenna duplexer 17 ... Transmission circuit 18 ... Receiving circuit 24-26 ... Dielectric resonator 31 ... Dielectric Body blocks 32a to 32c resonator holes 37 outer conductors 38 inner conductors 51 to 53 field effect transistors (reactance elements) 61 frequency variable filters 62, 63 resonators C6 to C9, C38 to C41 capacitors L5, L6, L16, L17 ... coupling coil D1 to D3, D10 to D15 ... PIN diode (reactance element) D4, D5 ... PIN diode

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J006 HA04 HA15 HA34 HD07 JA01 JA03 JA05 JA31 KA01 KA24 LA03 LA21 MA07 MA12 NA05 NB07 NC01 5K011 AA06 DA22 DA27 KA02 KA03

Claims (9)

[Claims] 1. A variable frequency filter for switching between a first band and a second band by a voltage-controllable reactance element, and a transmission / reception switch connected to an input / output terminal at one end of the variable frequency filter. An antenna duplexer comprising: 2. The antenna duplexer according to claim 1, wherein said variable frequency filter includes a low-pass filter. 3. The method according to claim 1, wherein the first and second bands of the frequency variable filter are divided into a plurality of frequency regions, respectively, and the reactance element is voltage-controlled to select one of the plurality of frequency regions. The antenna duplexer according to claim 1 or 2, wherein 4. The duplexer according to claim 1, wherein the resonator of the variable frequency filter is a dielectric resonator. 5. The antenna duplexer according to claim 1, wherein the reactance element is a PIN diode. 6. The antenna duplexer according to claim 1, wherein said reactance element is a field effect transistor. 7. The transmission / reception switch according to claim 1, wherein the transmission / reception changeover switch comprises a PIN diode.
An antenna duplexer according to claim 6. 8. The transmission / reception switch is GaAs.
7. The antenna duplexer according to claim 1, wherein the antenna duplexer is a switch IC. 9. A communication device comprising any one of the antenna duplexers according to claim 1. Description: