JPH084238B2 - Surface acoustic wave demultiplexer module and radio - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a duplexer used in a wireless device that performs simultaneous transmission / reception communication, such as an automobile telephone, and is particularly suitable for downsizing using a surface acoustic wave filter. The present invention relates to a module configuration of a simple demultiplexer.

A module is an assembly circuit that is assembled from multiple parts and elements and is considered as a single component unit that fulfills a certain function. Normally, multiple ICs are packaged in one package. It is what

[Conventional technology]

FIG. 2 is a block diagram showing the configuration of a conventional car telephone (for example, described in “Car Phone” Moriji Kuwahara, edited by The Institute of Electronics and Communication Engineers, p275-p306).

In FIG. 2, 201 is an antenna, 204 is a transmission filter, 205 is a pre-reception filter, 206 is a transmission line of a branch circuit, 207 is a reception line of a branch circuit, 208 is a reception low noise amplifier, and 209 is a post-reception filter. , 210 is a receiving mixer (mixer), 211 is a receiving IF amplifier and demodulator, 212 is a baseband system circuit, 213 is a receiving speaker, 214 is a transmitting microphone, 215 is a voltage controlled oscillator for local oscillation, 216 Is a synthesizer logic circuit, 217 is an isolator, 218 is a coupler circuit for automatic transmission power control, 219 is a power amplifier, 220 is a logic circuit for automatic transmission power control, 221 is a voltage control oscillator for transmission, and 222 is a bandpass filter. Further, a portion surrounded by a solid line 202 constitutes a conventional demultiplexer, and a portion surrounded by a broken line 203 indicates a portion integrated as a surface acoustic wave demultiplexer module in the present invention described later.

As described above, in a transceiver for simultaneous transmission / reception, in order to use a single antenna for both transmission and reception, a weak reception signal is sent to the receiver and a large transmission signal is sent to the antenna by using the difference in frequency. The demultiplexer that distinguishes and transmits plays an important role.

[Problems to be solved by the invention]

The conventional duplexer 202 uses a filter in which a cavity resonator filled with a ceramic having a high relative dielectric constant is cascade-connected (4-5 as the transmission filter 204 and 5-6 as the reception filter 205 are cascade-connected). However, there is a problem that the volume becomes very large.

Further, since the cavity resonator used in the conventional demultiplexer has a very large volume, the reception low-noise amplifier 208 and the reception post-stage filter configured by the cavity resonator as described above are used.
The 209 (three cavity resonators connected in series) was configured as separate circuit elements, and these circuit elements were connected on the motherboard of the radio device.

Therefore, the volume of each circuit element is large, and the dead space accompanying the connection is large, which makes it difficult to reduce the size.

Therefore, miniaturization of the duplexer 202 including the low-noise amplifier 208 and the post-reception filter 209 has been a big issue particularly in portable telephones and the like, which are strongly demanded to be miniaturized.

The present invention has been made in order to solve the problems of the prior art as described above, and reduces the size of the entire duplexer including a branch circuit, a transmission filter, a reception pre-stage filter, a reception post-stage filter, and a low noise amplifier. It is an object of the present invention to provide a compact duplexer module that can be achieved and at the same time reduce the dead space and can be applied to a compact car telephone or the like.

[Means for solving problems]

To achieve the above object, in the present invention, using a surface acoustic wave filter as a transmitting and receiving filter, and
By integrating the surface acoustic wave filters for transmission, pre-reception stage and post-reception stage, reception low-noise amplifier, input / output terminal, antenna terminal, etc. on the same pedestal, the reception low-noise amplifier to the post-reception stage filter are integrated. The whole duplexer including it is configured to be integrated as one module.

[Action]

As described above, in the present invention, since the surface acoustic wave filter is used as the transmitting / receiving filter, the size of the filter itself is reduced to about several tens of minutes as compared with the filter using the conventional cavity resonator. In addition, because these surface acoustic wave filters are integrated on the same pedestal as the receiving low-noise amplifier and branch circuit, the dead space becomes smaller, and the size of the demultiplexer as a whole is significantly reduced than before. It becomes possible.

A surface acoustic wave filter was recently announced by one of the inventors of the present application (M, Hikita “Low loss SAW filter for antenn
a duplexer "1983 IEEE Ultrasonic Symposium Proc, p77
~ P82), the performance is almost the same as the cavity resonator type filter, and the volume can be reduced to about one tenth of that of the cavity resonator type filter. is there.

〔Example〕

FIG. 1 is a perspective view of an embodiment of the present invention, in which a portion surrounded by a broken line 203 in FIG. 2 is modularized.

In FIG. 1, a pedestal 101 to which each element is attached is, for example, an aluminum plate, and in this embodiment, 3.5 cm × 2.5 cm.
I used the one.

Further, the transmission surface acoustic wave filter 107, the reception front stage surface acoustic wave filter 108, the reception rear stage surface acoustic wave filter 109,
Each of them is mounted in a package having a diameter of about 8 mm, and is mounted in a hole formed in the pedestal 101 with the terminal side facing upward.

The branch circuit is formed by a microstrip line on the alumina branch circuit substrate 103, and the output terminal of the transmission surface acoustic wave filter 107 and the input terminal of the reception front surface acoustic wave filter 108 are connected to the branch circuit as shown in the figure. The corresponding terminals are fixed by soldering, and the antenna terminal 110 is taken out.

The reception low-noise amplifier is formed by a hybrid circuit on the alumina reception low-noise amplifier substrate 104, and the output terminal of the pre-reception surface acoustic wave filter and the input terminal of the post-reception surface acoustic wave filter are soldered to their corresponding terminals. It is fixed.

Reference numeral 113 is a power supply terminal for supplying power to the reception low noise amplifier.

Further, an alumina transmission input terminal substrate 106 is provided in front of the transmission surface acoustic wave filter 107, and is connected to the transmission input terminal 111 via a microstrip line.

This microstrip line is a simple LC low-pass filter for attenuating the second and third transmitted harmonics.

Similarly, in the latter stage of the reception latter stage surface acoustic wave filter 109,
A reception output terminal 112 is provided through a reception output terminal substrate 105 made of alumina.

The branch circuit and the reception low noise amplifier can be formed on the same alumina substrate by using the same process (for example, thick film printing process).

As described above, in the duplexer module of the present invention,
On a pedestal 101 such as an aluminum plate, a branch circuit formed on an alumina substrate, a reception low noise amplifier, a circuit for a transmission input terminal,
Three surface acoustic wave filters 107, 108 and 109 mounted with a circuit for receiving output terminals and mounted in a package are mounted on the base 101.
, And each terminal is fixed to the corresponding terminal of each circuit board, so that the entire duplexer including the receiving low-noise amplifier to the receiving post-stage filter is integrated on one pedestal.

Therefore, it is possible to reduce the size of the filter itself by using the surface acoustic wave filter and also to make the dead space due to mounting in the module so small that it can be ignored. Compared with this, the size of the entire module can be significantly reduced, which can greatly contribute to the downsizing of the entire wireless device.

 Next, another embodiment of the present invention will be described.

Generally, the surface acoustic wave filter needs to have an external matching circuit in order to cancel the electrostatic capacitance between the electrodes, which is essentially included in the transducer for exciting the surface acoustic wave.

In a high frequency surface acoustic wave filter of about 800 MHz used in a car telephone to which the present invention is applied, this matching circuit is often formed by a relatively simple circuit such as a short stub or a combination of a short stub and a line.

However, in the configuration in which the demultiplexer, the low noise amplifier, and the post-reception stage filter are independently combined on the motherboard of the wireless device like the conventional combination, the above matching circuit needs to be formed on the motherboard. In a portable telephone, which is particularly required to be downsized, the volume occupied by this matching circuit cannot be ignored, and the effect of volume reduction is small even if a small surface acoustic wave filter is used.

In that respect, in the case where a circuit board such as a branch circuit and a low noise amplifier is included in the duplexer module as in the present invention, a third circuit is provided.
It is possible to form matching circuits on those circuit boards as shown.

First, in FIG. 3A, an output matching circuit 307 of the transmitting surface acoustic wave filter 107 and an input matching circuit 308 of the pre-reception surface acoustic wave filter 108 are formed on the branch circuit substrate 103.

Incidentally, 305 is a transmission side line of the branch circuit, 306 is a reception side line of the branch circuit, 303 is a terminal for connecting the output terminal of the transmission surface acoustic wave filter 107, 304 is the reception front surface acoustic wave filter 108. It is a terminal for connecting an input terminal.

Next, FIG. 3B shows a receiving low noise amplifier substrate 104.
The output matching circuit 313 of the receiving front surface acoustic wave filter 108 is provided on the top.
And an input matching circuit 314 of the post-reception stage surface acoustic wave filter 109.

Reference numeral 315 is a reception low-noise amplifier circuit, 310 is a terminal to which the output terminal of the pre-reception surface acoustic wave filter 308 is connected, and 311 is a terminal to which the input terminal of the post-reception surface acoustic wave filter 109 is connected.

By simultaneously forming the matching circuit of the surface acoustic wave filter on the branch circuit substrate and the receiving low noise amplifier substrate as described above, it is possible to further reduce the size of the module.

Further, in the case of further miniaturization, the output matching circuit of the pre-reception surface acoustic wave filter and the input matching circuit of the post-reception surface acoustic wave filter and the matching circuit of the reception low noise amplifier are further shared to further increase the size. The effect of is obtained.

Next, in the above embodiments, the transmission filter,
I explained the module that integrated the branch circuit, pre-reception filter, reception low-noise amplifier, and post-reception post-filter, but about parts that can be formed by the same process using the same circuit board as the branch circuit and reception low-noise amplifier. In general, inclusion in the module makes a greater contribution to downsizing of the entire wireless device.

For example, referring to FIG.
Since the mixer 210 connected to the subsequent stage can be configured by a hybrid circuit using an alumina substrate similarly to the branch circuit, etc., this mixer is also integrated in the duplexer module. It is possible to further reduce the size of the entire wireless device.

 The same holds true for the sender.

Generally, in a so-called cellular radio such as a car telephone (portable telephone), it is necessary to switch the transmission power level in several steps according to a command from a base station.

This is automatically transmitted power control (APC = Automatic Power Con
This power control monitor circuit is the second
As shown in the figure, a part of the transmission power is taken out by the coupler 218 or the like, and is directly or detected and sent to the power control logic circuit 220.

Like the branch circuit, this monitor circuit is also generally formed on the alumina substrate by a microstrip line or the like, so that it can be included and integrated in the duplexer module.

FIG. 4 shows an embodiment in which the above monitor circuit is formed on the branch circuit substrate 103 and integrated in the duplexer module.

First, in FIG. 4 (A), a coupling line 408 that is electromagnetically coupled is provided close to the transmission side line 305 of the branch circuit on the branch circuit substrate 103, and a part of the transmission power is used for monitoring as a monitor. The terminal 405 is taken out of the module. 409 is a terminating resistor.

Next, in FIG. 4 (B), in addition to the coupled line 417, a detection diode 418 is further provided to detect the detection output outside the module.
That is, a DC level signal is transmitted.

In addition, 414 is a monitor terminal, 419 is a terminal resistor, 420 is a capacitor, and 421 is a resistor.

In addition to the above combinations, various methods are conceivable for the method of connection, the place of connection, and the method of taking out to the outside,
In any case, by providing the automatic transmission power control monitor circuit and its output terminal in the duplexer module, it is possible to further reduce the size of the entire radio device.

In the above description, the low noise amplifier, the mixer, and the like are shown as an example of a hybrid circuit, but the present invention can be similarly applied to the place of the monolithic amplifier or the monolithic mixer in which the circuit is monolithic. Can be done.

Further, the surface acoustic wave filter is treated as being mounted in the package, but when the surface mounting of the surface acoustic wave filter becomes possible due to improved reliability, it may be mounted as a chip.

〔The invention's effect〕

As described above, in the present invention, a surface acoustic wave filter that is significantly smaller than the conventional one is used as a filter, and a transmission filter, a branch circuit, a reception pre-stage filter, a reception low noise amplifier, a reception post-stage filter, etc. are integrated. Since it is modularized as, the filter itself can be miniaturized and the dead space between each element can be greatly reduced, which allows the duplexer module to be significantly smaller than before. Became.

Further, by providing a matching circuit of the surface acoustic wave filter on the substrate of the branch circuit or on the substrate of the receiving low noise amplifier, the size can be further reduced, and further, the output matching circuit of the receiving front surface acoustic wave filter and the above If the input matching circuit of the post-reception surface acoustic wave filter and the matching circuit of the receiving low-noise amplifier are shared, the size can be further reduced.

Also, in the case where the receiving mixer and the monitor circuit for automatic transmission power control are integrated as a duplexer module,
It is possible to obtain many excellent effects such as further miniaturization of the entire wireless device.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a conventional car telephone, and FIGS. 3 and 4 are other embodiments of the present invention. <Explanation of symbols> 101 ... Pedestal 102 ... Lid 103 ... Branch circuit board 104 ... Reception low noise amplifier board 105 ... Reception output terminal board 106 ... Transmission input terminal board 107 ... Transmission elasticity Surface acoustic wave filter 108 …… front receiving surface acoustic wave filter 109 …… rear receiving surface acoustic wave filter 110 …… antenna terminal 111 …… transmission input terminal 112 …… reception output terminal 113 …… power supply terminal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshikatsu Ishida 1410 Inada, Katsuta City, Ibaraki Prefecture Inside the Tokai Plant, Hitachi, Ltd. (56) References JP-A-58-197912 (JP, A) JP-A-59- 158117 (JP, A) JP-A-4-196827 (JP, A) Actually opened Sho 57-200943 (JP, U) Actually opened 61-100052 (JP, U)

Claims (9)

[Claims] 1. A transmission input terminal, a transmission surface acoustic wave filter, an output matching circuit of the transmission surface acoustic wave filter,
A branch circuit for coupling transmission / reception, an input matching circuit of the front-end surface acoustic wave filter, the front-end surface acoustic wave filter, an output matching circuit of the front-end surface acoustic wave filter, a reception low-noise amplifier, and a post-reception stage The input matching circuit of the surface acoustic wave filter, the reception post-stage surface acoustic wave filter, and the reception output terminal are arranged on the same pedestal, and they are connected in the above order, and the antenna is provided at the branch point of the branch circuit. And at least the branch circuit, the receiving low noise amplifier, the output matching circuit of the transmitting surface acoustic wave filter, the input matching circuit of the receiving front stage surface acoustic wave filter, and the output of the receiving front stage surface acoustic wave filter. A surface acoustic wave component characterized in that a matching circuit and an input matching circuit of the receiving surface acoustic wave filter are arranged on the pedestal through a substrate. Vessel module. 2. An output matching circuit of the pre-reception surface acoustic wave filter, an input matching circuit of the reception low noise amplifier, an input matching circuit of the reception rear surface acoustic wave filter, and an output matching circuit of the reception low noise amplifier. The surface acoustic wave demultiplexer module according to claim 1, which is common. 3. A receiving mixer provided on a substrate is disposed on the pedestal, and is connected to a subsequent stage of the receiving post-stage surface acoustic wave filter. The surface acoustic wave demultiplexer module according to item 2. 4. The surface acoustic wave demultiplexer module according to claim 3, wherein the receiving mixer is a monolithic mixer. 5. The elasticity according to any one of claims 1 to 4, wherein a monitor circuit for automatic transmission power control and an output terminal thereof are provided on a substrate of the branch circuit. Surface wave demultiplexer module. 6. The surface acoustic wave demultiplexer module according to claim 1, wherein the receiving low noise amplifier is a monolithic amplifier. 7. The surface acoustic wave demultiplexer module according to any one of claims 1 to 6, wherein the surface acoustic wave filter is mounted on a chip. 8. The surface acoustic wave demultiplexer module according to claim 1, wherein the base is made of aluminum and the substrate is made of alumina. 9. A radio equipment comprising the surface acoustic wave demultiplexer module according to any one of claims 1 to 8. Description: