JP3351448B2 - Variable frequency band splitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication device in a microwave band, and more particularly to a duplexer used in a portable telephone.

[0002]

2. Description of the Related Art A 900 MHz band cellular telephone system, for example, E-TACS (Extended Total Access Comu) implemented as a car telephone / mobile telephone system in the United Kingdom.
Taking the specifications of the nications system) as an example, the frequency band is 872 to 9 for mobile transmission as shown in the frequency allocation of FIG.
05MHz (M), base transmission is 917 ~ 950MHz
(B) and has been specified, each have a transmission and reception bandwidth of 33MH z, adjacent channel spacing of a number of speech channels in the band is 25 kHz, the transmission and reception channels of simultaneous calls Ji
The frequency interval of the channel is specified as 45 MHz . During an actual call, one channel corresponding to each transmission and reception is used at an interval of 45 MHz. However, since it is not specified which channel to use according to the service area or the traffic situation, a mobile terminal such as a mobile phone performs both transmission and reception.
It is designed to accommodate to any channel in the bandwidth 33MHz of Re respectively. Therefore, the duplexer used for the antenna duplexer of the transceiver used for this,
It is composed of a combination of two filters each having a band on the other side as a stop band and a whole band having a width of 33 MHz as a pass band.

[0003]

However, the upper limit frequency of the transmission band (M) and the lower limit frequency of the reception band (B) are different from each other.
Since this filter has an interval of only 12 MHz, this filter is required to have a steep characteristic, and must be of a high order. For example,
BEF (band rejection filter) on the transmitting side filter and polarized BPF (band pass filter) on the receiving side, 4 mm
Even when a dielectric coaxial resonator having corners is used, the order of each of the five stages is required. FIG. 2 shows an example of characteristics of a conventional transmission-side band rejection filter. The insertion loss in the transmission band (M) of the transmission-side filter, which is particularly important for reducing power consumption, is 2.5 dB as shown in FIG. There is the disadvantage that 44% of the input power is consumed by this duplexer.

In a terminal of a cellular telephone system,
A long talk time due to miniaturization and low power consumption is a user's greatest demand, and realizing this is the biggest issue for a manufacturer. That is, reduction of the insertion loss of the duplexer is an urgent task. In the case of other cellular telephone systems, the problem is the same, although there are some differences in transmission / reception bandwidths and transmission / reception frequency intervals.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and has a small insertion loss, an excellent demultiplexing function for any channel in the transmission / reception band, and a low cost. It is an object of the present invention to provide a duplexer which is reduced.

[0006]

According to the present invention, there is provided a frequency band variable duplexer, comprising: a coupler to which a transmitting / receiving antenna is connected;
The signal of the transmission frequency band connected to the transmitter side of the coupler is
At a predetermined interval from the transmission frequency band
Of the same frequency band as the transmission frequency band
A transmission filter for blocking signals in a transmission frequency band;
Connected to the receiver side of the coupler,
Signal and block signals in the transmission frequency band.
And a reception filter for the transmission frequency band.
The transmission wave of one selected transmission channel and the transmission wave
Before selected to have a certain frequency spacing with the frequency
The reception wave of one reception channel within the reception frequency band is
A demultiplexer for demultiplexing, wherein the transmission frequency band and the reception frequency band are respectively divided into a plurality of sections corresponding to the same number.
Multiple transmission bandwidth divisions and multiple reception bandwidth divisions
Is set, and the transmission filter has a small number of movable settings.
At least one attenuation pole is used to divide the plurality of reception band sections.
A high-band stop band characteristic for blocking a signal in one of the reception band sections , and the low-band side of the high-band stop band is the one reception band.
One of the plurality of transmission band sections corresponding to the area section
It is set to have a low-pass band characteristic of passing a signal of the transmission baseband section with <br/>, and the transmitting said selected
By changing the frequency of the attenuation pole by the band control signal in accordance with said reception channel as the low
Pass band characteristics and the high frequency stop band characteristics and its relative circumferential
With the selected transmission channel while maintaining the wave number relationship
The one transmission band section in which each reception channel is located
And a low-pass band rejection filter configured to be variably set to one and the one reception band division .

Further, a transmission / reception shared antenna is connected.
A combiner, and a transmission frequency band connected to the transmitter side of the combiner.
Signal in the specified frequency band and a predetermined interval from the transmission frequency band.
And set to the lower frequency and equal to the transmission frequency band
Sending off for blocking the signal in the reception frequency band of the band
And a filter connected to a receiver side of the coupler.
Passing the signal in the wave number band and the signal in the transmission frequency band
A receiving filter for blocking the transmission frequency.
A transmission wave of one selected transmission channel within several bands,
Select so as to have a certain frequency interval with the frequency of the transmission wave.
Of one receiving channel in the selected receiving frequency band
A duplexer for splitting a received wave, wherein the same number of duplicates respectively correspond to the transmission frequency band and the reception frequency band.
Multiple transmission band divisions and multiple reception bands divided into several divisions
Shin band section and is defined, the transmission filter is moved set
The plurality of receivers are provided by at least one definable attenuation pole.
A low band stop band characteristic for blocking a signal in one reception band section of the reception band section , and a high band side of the low band stop band.
The plurality of transmission band divisions corresponding to one reception band division
One passing signals of the transmission band division is set to have a high-pass band characteristics, and the attenuation pole by the band control signal in accordance with said reception channel with the selected said transmission channel of , The high-pass band characteristic and the low-band stopband characteristic maintain the relative frequency relationship of the selected transmission band.
The one where the communication channel and the reception channel are respectively located
And a high-pass band rejection filter configured to be variably set to the transmission band division and the one reception band division .

[0008]

FIG. 3A is a structural example of a duplexer showing an embodiment of the present invention. The embodiment of FIG. 3A is a duplexer used for a mobile unit, 11 is a coupler, 12 is a transmission filter,
Reference numeral 13 denotes a reception filter. The transmission filter 12 is a frequency band variable BEF (variable BEF) that can variably set the frequency band with external band control signals V _CTL1 and V _CTL2 , instead of the conventional BEF.
It forms the main part of the present invention.

FIG. 3B shows band characteristics a ₁ , a ₂ , and band characteristics corresponding to band control signals V _CTL1 and V _CTL2 when the transmission band (M) and the reception band (B) are both divided into four sections . a ₃ ,
shows the a _4. 4A and 4B are diagrams illustrating examples of band characteristics, where FIG. 4A shows transmission characteristics and FIG. 4B shows reflection characteristics. Band (M),
When sending and receiving the channel of each segment (1) in the (B) is a band characteristic to a _1. Division (2), (3),
In the case of (4), the characteristics are controlled to characteristics a ₂ , a ₃ and a ₄ respectively. In other words, the low pass band characteristics and the high stop band characteristics
Selected transmission channel while maintaining its relative frequency relationship.
Channels and receive channels are variably set in their respective locations.
Is determined.

Although a specific circuit configuration of the transmission filter (variable BEF) 12 will be described later, a BEF using a diode as a switching element is used as a transmission-side filter for which loss reduction is one of the important purposes. For example, a 33 MHz transmission / reception band is divided into four bands.
Divided into (classification), giving the band control signal in conjunction with the traffic channel signal to the variable BEF 1 2. This band control signal V
_With the combination of _CTL1 and _VCTL2 , in this example, four frequency bands can be variably set corresponding to the communication channel.
According to the characteristics actually realized by realizing this, as shown in FIG. 4, the insertion loss of the pass band can be reduced to about 1 dB while the stop band attenuation is maintained as in the related art. The power consumption in this duplexer is 20% of the input power, which is less than half of the conventional example. Therefore, when the present invention is applied to a mobile phone or the like, an extremely long talk time can be obtained because the battery consumption is small.

FIG. 5 is a diagram showing an example of a specific circuit configuration of the band variable BEF of the transmission filter 12 according to the present invention. In the figure, 1
Is an input terminal to which a transmission unit (T _x ) is connected. An output terminal 2 is connected to the coupler 11 as shown in FIG. C ₁ and C ₂ are resonance capacitors, and Z ₁ and Z ₂ are distributed constant lines. C ₁ and Z ₁ and C ₂ and Z ₂ form a series resonance circuit, and are connected by a coupling coil L _4. ing. The two series resonance circuits are connected between the grounds as parallel arms, and form a stop band at different resonance frequencies .
The attenuation pole. L ₃ and L ₅ are coils for parallel resonance, and form a pass band by exhibiting parallel resonance with the low-frequency side capacitance components of the two series resonance circuits. That is, this filter is a low-pass filter based on the notch type BEF.

C ₃ , C ₄ , C ₇ , and C ₈ connected to the intermediate connection point of the two series resonance circuits are capacitors for changing the frequency of the attenuation pole, and are switching diodes D ₁ and D ₂ , respectively. , D ₃ , D _4, etc., are grounded. Diode D ₁ and the resistor R ₁ to the anode side of the D _2, the band control signal voltage V _CTL1 through R ₂ are adapted to be applied, the diode D ₁ by the band control signal voltage V _CTL1, D ₂ on / off By turning on / off the capacitors C ₃ and C ₄ ,
The resonance frequencies of the two series resonance circuits, that is, the two attenuation poles in the stop band can be simultaneously shifted. Also for the diodes D ₃ and D ₄ , the band control signal voltage V _CTL2
Similarly, by turning on / off by the capacitor C ₇ ,
C ₈ can be turned on / off. Capacitor C
₃ , C ₄ , C ₇ , and C ₈ are set to predetermined values,
By applying the band control signal voltages V _CTL1 and V _CTL2 as shown in FIG. 3 (B), four types of band characteristics a ₁ , a ₂ and a
_3, a ₄ to can be variably set. L ₁ and L in FIG.
₂ , L ₆ and L ₇ are diodes D ₁ , D ₂ , D ₃ and D ₄
This is a coil having an inductive reactance that cancels out the capacitive reactance described above, and is added to further ensure the frequency variable effect.

When the band characteristics are a ₂ , a ₃ and a ₄ excluding a ₁ , a forward current flows through the diode,
The current consumption increases during standby, but the transmission power is not output from the transmitter during standby. Therefore, it is possible to solve the problem by providing a means of flowing about several tens of μA to maintain the characteristics. The power handling capability, in this embodiment, when the characteristics to turn on the four diodes was a ₄ (current flows 2 mA), the input level is never saturated to more than + 34 dBm. When all diodes were turned off by applying a negative voltage, they did not saturate up to +28 dBm at -12 V and +32 dBm at -20 V, depending on the value of the reverse bias voltage. This is a sufficient power withstand performance for a mobile phone having an output of about 0.5 W.

The above embodiment is based on the UK mobile telephone / cellular telephone system E as described at the beginning of the description of the prior art.
-A configuration example that satisfies the TACS specification, for example,
When the present invention is applied to the specification of the Japanese digital cellular system (PDC), the transmission / reception interval is 130 MHz.
Since z is specified and the interval is wider than 45 MHz in the UK, the specification can be sufficiently satisfied with one attenuation pole. Therefore, construction of the BEF of the transmitting side shown in FIG. 5, it is possible to achieve the object of the present invention in the configuration of the left or right half excluding coupling coil L _4. It is clear that the operation in this case is exactly the same as in the above embodiment.

The variable frequency band BEF used in the embodiment of the present invention has a transmission frequency band and a reception frequency band, respectively.
Stop band in one of the four divided sections
It is a low-pass filter configuration that can variably set the characteristics and the passband characteristics while maintaining the relative frequency relationship .
If divided into division, when divided into three sections, 及
In the case of a high-pass filter configuration, as a frequency band variable filter, reference numbers P060057 (Japanese Patent Application No. 6-129863) and P06 on May 20, 1994.
0056 (Japanese Patent Application No. 6-129962) can be applied. Further, the BP of the receiving side
F may be configured in place of the variable band BEF.

[0016]

By implementing the present invention, the following effects can be obtained. (1) Insertion loss is less than half of the conventional example, and low power consumption can be achieved. (2) The order of the filter can be reduced, and the size and cost can be reduced. (3) When the present duplexer is used for a mobile phone, the talk time is greatly increased because the battery is not consumed much.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a frequency arrangement.

FIG. 2 is a diagram illustrating a conventional transmission filter characteristic example.

FIG. 3 is a configuration diagram showing an embodiment of the present invention.

FIG. 4 is a characteristic example diagram of a transmission filter which is a main part of the present invention.

FIG. 5 is a circuit example diagram of a transmission filter which is a main part of the present invention.

[Explanation of symbols]

Reference Signs List 1 input terminal 2 output terminal 11 coupler 12 transmission filter 13 reception filter C ₁ , C ₂ resonance capacitors C ₃ , C ₄ , C ₇ , C ₈ band variable capacitors C ₅ , C ₆ , C ₉ , C ₁₀ capacitors L ₁ , L ₂ , L ₃ , L ₅ , L ₆ , L ₇ coil L ₄ coupling coil Z ₁ , Z ₂ distributed constant line D ₁ , D ₂ , D ₃ , D ₄ switching diode V _CTL1 control voltage R ₁ , R ₂ , R ₃ , R ₄ Control voltage supply resistors Q ₁ , Q ₂ FET

Continued on the front page (72) Inventor Kazuo Murata 3-14-20 Higashinakano, Nakano-ku, Tokyo International Electric Company (72) Inventor Fujio Ishibashi 3-14-20 Higashinakano, Nakano-ku, Tokyo International Electric Stock In-house (72) Inventor Hirohisa Takahashi 3--14-20 Higashinakano, Nakano-ku, Tokyo International Electric Co., Ltd.

Claims (2)

(57) [Claims] 1. A coupler to which a transmitting / receiving antenna is connected.
And a signal in a transmission frequency band connected to the transmitter side of the coupler.
Signal at a predetermined interval from the transmission frequency band.
A band set to the higher wave number and equivalent to the transmission frequency band
Transmit filter to block signals in different receive frequency bands
And the reception frequency band connected to the receiver side of the coupler.
Band signal and block the transmission frequency band signal
And a reception filter for transmitting the transmission frequency band.
A transmission wave of one selected transmission channel in
Selected to have a certain frequency spacing with the wave frequency
Received wave of one receiving channel within the receiving frequency band
A demultiplexer for demultiplexing the door, said the transmission frequency band and the reception frequency band respectively
Multiple transmission bands divided into the same number of corresponding sections
A band section and a plurality of reception band sections are defined, and the transmission filter is configured to control one of the plurality of reception band sections by at least one movable and configurable attenuation pole.
And the high-frequency stop band characteristics to prevent signal reception baseband section, one transmission band District of the plurality of transmit baseband section that lower-frequency side of the high band stop band corresponding to the single reception band segment
It is set to have a low-pass band characteristic to pass the partial signal, and said transmission channel and before said selected
By changing the frequency of the attenuation pole by a band control signal corresponding to the reception channel , the low-pass band characteristic is changed.
And the selected transmission channel and reception channel while maintaining the relative frequency relationship between the transmission and reception characteristics.
The one transmission band segment and the one
A variable band splitter characterized by being a low-pass band rejection filter configured to be variably set to a reception band division of (1). 2. A coupler to which a transmitting / receiving antenna is connected.
And a signal in a transmission frequency band connected to the transmitter side of the coupler.
Signal at a predetermined interval from the transmission frequency band.
A band set to the lower wave number and equivalent to the transmission frequency band
Transmit filter to block signals in different receive frequency bands
And the reception frequency band connected to the receiver side of the coupler.
Band signal and block the transmission frequency band signal
And a reception filter for transmitting the transmission frequency band.
A transmission wave of one selected transmission channel in
Selected to have a certain frequency spacing with the wave frequency
Received wave of one receiving channel within the receiving frequency band
A demultiplexer for demultiplexing the door, said the transmission frequency band and the reception frequency band respectively
Multiple transmission bands divided into the same number of corresponding sections
And a plurality of reception band sections are defined, and the transmission filter is configured to control one of the plurality of reception band sections by at least one movable and configurable attenuation pole.
A high-pass band characteristic for blocking the signal reception baseband section, one transmission band District of the plurality of transmit baseband section that the high-frequency side of the low band stop band corresponding to the single reception band segment
It is set to have a high-pass band characteristic to pass the partial signal, and said transmission channel and before said selected
By changing the frequency of the attenuation pole by the band control signal corresponding to the serial reception channels, the high pass band JP
And the selected transmission channel and reception channel while maintaining the relative frequency relationship between the transmission and reception characteristics.
The one transmission band segment and the one
A variable band splitter characterized by being a high-pass type band rejection filter configured to be variably set to a reception band division of (1).