JP2002353851A - High frequency signal processing circuit and wireless phone communication unit employing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency signal processing circuit that can obtain a high frequency side branch reception signal extracted waveform suitable for high quality processing for an operating frequency band extract signal, resulting in contributing to improvement of communication quality of a wireless phone communication unit. SOLUTION: A high frequency switch module 2 has a plurality of switch circuits 42A, 42B that switch connection to an antenna side input/output section ANT from reception output terminals RX1, RX2 for output of a branch reception signal with each frequency band from a branch circuit 44 having a high pass filter circuit 46 to reception circuits 36A, 36B of the wireless phone communication unit 1 and from transmission input terminals TX1, TX2 receiving a transmission output signal from transmission circuits 32A, 32B of the wireless phone communication unit 1. Further, a low pass filter circuit 43 for adjustment to reduce a signal component with a frequency being a predetermined frequency or over from the branched reception signal corresponding to the switch circuit 42B handling the signal branched by the high pass filter circuit 46 in the switch circuits 42A, 42B is placed between the high pass filter circuit 46 and the antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency signal processing circuit used for a radio telephone communication device and a radio telephone communication device used therefor. A wireless telephone communication device to which the present invention is applied means any device that performs two-way communication using a wireless telephone line network, such as a mobile phone or a PHS (Personal Computer).
al Handy phone System), as well as mobile phones with built-in terminal functions and, conversely, portable terminal devices such as portable computers with telephone line connection functions, and wireless telephone line connections The concept also includes a modem, a portable computer incorporating the modem, and the like.

[0002]

2. Description of the Related Art In the above-mentioned radio telephone communication apparatus, for example, a digital portable telephone, a high-frequency switch is used to switch between a connection between an antenna and a transmission circuit and a connection between an antenna and a reception circuit. In particular, in recent years, the number of spreads of digital mobile phones has been rapidly increasing, and new types of communication systems, such as GSM, DCS, PCS, PDS, and CDMA, have been developed and adopted one after another. Also, with the increase in the number of subscriber lines, the frequency band of radio waves to be used has been expanded from the initial several hundred MHz band to the GHz band, and various frequency bands are allocated according to communication systems.

[0003] By the way, the communication system of the digital portable telephone is often different depending on the communication company or country or region. For example, GSM is a generalized system in Europe. In the United States, a DCS that uses a similar system but uses a different frequency band is often used. In this case, a mobile phone compatible with DCS can be used without any problem in the United States where the system is generalized.
Cannot be used in mainstream Europe, and GSM-compatible phones cannot be used in the United States. This is very inconvenient for a user who frequently travels back and forth between areas using different communication systems because he must always carry two telephones. In addition, when different communication systems coexist in the same region, such as in Japan, there is a desire that the same user uses the different communication systems in order to take advantage of each communication system.

Therefore, in order to meet such needs,
Multi-band telephones that can handle transmission / reception systems in a plurality of different frequency bands with one telephone have been developed and are becoming popular. Such a multi-band telephone is provided with a duplexer that separates a received signal into signals of each frequency band. Of these, the demultiplexed reception signal in the highest frequency band (hereinafter, referred to as the high-frequency demultiplexed reception signal) is extracted by a high-pass filter circuit, and is further allocated to each scheme from the extracted demultiplexed reception signal. The signal of the used frequency band is extracted by the band-pass filter circuit. The allocated frequency band is generally set to a narrow band of about 50 to 75 MHz for effective use of radio wave resources, and a narrow band filter circuit suitable for the band is used for the band pass filter circuit.

[0005]

In the above conventional method,
From the high-frequency-side demultiplexed signal extracted by the high-pass filter circuit, a signal in the used frequency band is extracted by the narrow-band filter circuit. At this time, a signal component on the higher frequency side than the used frequency band in the demultiplexed received signal is extracted. (Residual signal component)
However, there is a problem that the waveform of the used frequency extraction signal is easily degraded and the noise is increased, and the communication quality is easily deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to obtain a high-frequency-side branching reception signal extraction waveform which is convenient for improving the quality of a frequency band extraction signal to be used, and which contributes to improvement in communication quality of a radio telephone communication apparatus. An object of the present invention is to provide a signal processing circuit and a wireless telephone communication device using the same.

[0007]

SUMMARY OF THE INVENTION A high frequency signal processing circuit according to the present invention is a high frequency signal processing circuit used in a radio telephone communication apparatus corresponding to a plurality of frequency bands, and solves the above-mentioned problems. In order to be connected to an antenna and used for input / output of an antenna reception signal and an antenna transmission signal, an antenna-side input / output terminal is connected to the antenna-side input / output terminal, and includes a high-pass filter circuit, A demultiplexing circuit that demultiplexes the received signal into a transmission and reception circuit system that individually processes a plurality of frequency bands,
A reception output terminal that is provided between a transmission / reception circuit corresponding to each of a plurality of frequency bands and outputs a branch reception signal from the branching circuit to a reception circuit side of the wireless telephone communication device; A plurality of switch circuits for switching a connection to an antenna-side input / output terminal with a transmission input terminal to which a transmission signal from the circuit is input; and a signal that is demultiplexed by a high-pass filter circuit in a demultiplexer circuit among the plurality of switch circuits. Circuit (hereinafter, referred to as a high-frequency switch circuit) and an antenna-side input / output terminal. An adjustment low-pass filter circuit for reducing a signal component.

A radio communication telephone apparatus according to the present invention includes a high-frequency signal processing circuit according to the present invention, an antenna connected to the antenna-side input / output terminal of the high-frequency signal processing circuit, and a reception output terminal. A low-pass filter for adjusting, comprising: a band-pass filter circuit for extracting a used frequency band from a received wave signal; a receiving circuit connected to a receiving output terminal; and a transmitting circuit connected to a transmitting input terminal. The circuit has a cutoff frequency on a higher frequency side than a pass band of a bandpass filter circuit for extracting a used frequency corresponding to the high-frequency side switch circuit (hereinafter, referred to as a bandpass filter circuit for extracting a high-frequency used frequency). Characterize.

According to the high-frequency signal processing circuit and the radio communication telephone device of the present invention, the adjustment low-pass filter circuit can reduce the signal components on the higher frequency side than the operating frequency band from the high-frequency side demultiplexed reception signal. . As a result, problems such as deterioration of the extracted waveform and increase in noise of the band pass filter circuit for extracting the higher frequency used due to the residual signal component are effectively suppressed, and the communication quality can be improved. Further, in the present invention, since the adjustment low-pass filter circuit is provided between the high-frequency side switch circuit and the antenna (antenna-side input terminal), the transmission signal from the transmission circuit is also adjusted by the adjustment low-pass filter circuit. Will pass through. Therefore, a signal component (residual signal component) on the higher frequency side than the used frequency band can be reduced from the transmission signal. In other words, a single low-pass filter circuit can attenuate both the transmission signal and the reception signal on the high frequency side, thereby contributing to a reduction in the number of components.

A low-pass filter on the transmission signal side (transmission-side low-pass filter) has conventionally been used for the purpose of, for example, removing background noise on the high-frequency side. It was provided between the area side switch circuit. However, in this configuration, the transmission-side low-pass filter is disposed at a position close to the input terminal of the transmission signal. Will be sent more. Therefore, noise and the like picked up by the wiring during this period cannot be removed by the transmitting low-pass filter. However, in the configuration of the present invention, since the adjustment low-pass filter circuit arranged so as to allow transmission signals to pass therethrough is located on the side closer to the antenna (antenna-side input terminal), the wiring distance becomes longer because of the transmission input terminal. Since the noise picked up by the wiring can be finally removed by the adjustment low-pass filter circuit at a time, the noise remaining in the transmission signal can be hardly generated.

The high-frequency signal processing circuit according to the present invention is characterized in that the components of the branching circuit and the plurality of switch circuits are formed by stacking a circuit pattern and a dielectric layer in a laminate.
The inner layer can be formed in the form of a component pattern constituting a circuit pattern. In this case, the antenna input / output terminal and the reception output terminal and the transmission input terminal of each switch circuit can be exposed on the surface of the laminate. As a result, the number of components can be reduced and component mounting can be simplified, and the overall circuit can be made more compact. Therefore, for example, it can be easily incorporated into a mobile phone having a limited internal space. Also, the components of the low-pass filter circuit for adjustment can be formed in the laminate in the form of component patterns constituting the circuit pattern, and similarly, the number of components can be reduced and the circuit configuration can be made compact. For all of the demultiplexing circuit, the plurality of switch circuits, and the low-pass filter circuit for adjustment, the effect of compactness can be maximized by forming the components inside the laminate.

Here, "the components of the demultiplexing circuit, the plurality of switch circuits, or the low-pass filter circuit for adjustment are internally layered in the laminate" does not necessarily mean that all of the components are internally layered. That is, some components whose inner layers are not suitable for the laminated body, such as semiconductor discrete components such as diodes and transistors, integrated circuits such as ICs and LSIs, and even capacitors with large capacitance,
It can be placed outside the laminate or mounted on the surface of the laminate.

For example, when the switch circuit is configured to include a diode and a strip resonator, the diode is surface-mounted on a laminate, and the strip resonator of the switch circuit, the demultiplexer circuit, and the adjustment low-pass filter circuit are laminated. By arranging it inside the body, the occupied space of the high-frequency signal processing circuit in the radiotelephone communication device is significantly greater than when the demultiplexing circuit, the low-pass filter circuit for adjustment, and the switch circuit are composed of individual chip components. Can be reduced.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating an electrical configuration of a dual-band digital mobile phone (hereinafter, also simply referred to as a mobile phone), which is an example of a wireless telephone communication device that handles a plurality of frequency bands. The mobile phone 1 uses I
/ O port 11 and CPU 12 and RO connected thereto
A control microprocessor 10 as a main control unit composed of an M13, a RAM 14 and the like, and its I / O port 1
Reference numeral 1 denotes a dial input unit 5 composed of a well-known ten-key type push button, an on-hook / off-hook switch 6 for switching the mobile phone 1 between an on-hook state and an off-hook state, and a band switch for switching a used frequency band. 7 is connected. The receiver 3 is connected via an amplifier 15 and a D / A converter 16, the transmitter 4 is connected via an amplifier 17 and an A / D converter 18, and a liquid crystal monitor (LCD) 19 controls a monitor control circuit 20. Each is connected to the I / O port 11 through the I / O port 11.

A telephone connection circuit 9 is connected to the I / O port 11. The telephone connection circuit 9 includes a first modulation unit 32 corresponding to a lower frequency band of the two use frequency bands.
A, the first transmission unit 33A (these constitute a first transmission circuit), the first reception unit 35A and the first demodulation unit 36A (these constitute a first reception circuit), also corresponding to those on the high frequency side The second modulation unit 32B, the second transmission unit 33B (these constitute a second transmission circuit), the second reception unit 35B and the second demodulation unit 36B (these constitute a second reception circuit), and the communication carrier The frequency synthesizer 34 for synthesizing at a required frequency, the high-frequency signal processing circuit 2 of the present invention, the antenna 39 connected thereto, and the respective demultiplexers 44 (FIG. 2: described later) included in the high-frequency signal processing circuit 2 It is configured to include a working frequency extraction band-pass filter circuit 40A, 40B and the like for extracting a signal in a working frequency band from the wave reception signal. Although not shown, the telephone connection circuit 9 is not shown.
Also includes a control radio wave transmitter for handover.

The components of the telephone connection circuit 9 other than the high-frequency signal processing circuit 2 are well known and are not different from general digital mobile phones, and therefore detailed description is omitted. The basic operation of the mobile phone 1 is the same as that of the well-known one, but the outline is as follows.
That is, the voice input from the transmitter 4 is amplified by the amplifier 17, further digital-converted by the A / D converter 18, and then modulated by the modulator (32A or 32B) corresponding to the selected use frequency band. The signal is further combined and amplified with the carrier by the transmitting unit (33A or 33B) and transmitted from the high-frequency signal processing circuit 2 and the antenna 39.
On the other hand, the received radio wave is received by the receiving section (35A or 35B) corresponding to the selected use frequency band via the antenna 39 and the high-frequency signal processing circuit 2, and after the carrier component is removed, the demodulation section (36A or 36B). ) Is demodulated into a digital audio signal and output from the receiver 3 via the D / A converter 16 and the amplifier 15.

The high-frequency signal processing circuit 2 converts the reception signal and the transmission signal into switch control signals (VC1 to VC
4: Signal control is performed by the control microprocessor 10), and switching is performed in a time-division manner. On the other hand, the switching of the used frequency band is performed by the band changeover switch 7 in this embodiment.
Is performed by the control microprocessor 10, but a band scan may be performed using the frequency synthesizer 34 to automatically switch to a suitable frequency band. In the present embodiment, the first used frequency band (band) corresponds to a communication system of less than 1 GHz (for example, a GSM system using a 900 MHz band), and the second used frequency band of 1 GHz or more ( For example, it corresponds to the DCS1800 system using a 1.8 GHz band. The switching process performed by the control microprocessor 10 mainly includes the modulation sections 32A / 32B and the demodulation sections 36A in the I / O port 11.
/ 36B port switching processing and frequency synthesizer 3
4 is a process for switching the designated frequency to 4.

FIG. 2 is a block diagram showing an electrical configuration of the high-frequency signal processing circuit 2. As shown in FIG. The high-frequency signal processing circuit 2 is used by being connected to the antenna 39 as described above, and has an antenna-side input / output terminal ANT used for input / output of an antenna reception signal and an antenna transmission signal.
As shown in FIG. 10, the antenna reception signal () from the antenna-side input / output terminal ANT is supplied to the branching circuit 44 (FIG. 2) by the low-side branch reception signal () and the high-side branch reception signal () And split into two. Among them, the high-frequency-side demultiplexed reception signal is extracted and demultiplexed by the high-pass filter circuit 46 in FIG. 2, and the low-frequency-demultiplexed reception signal is similarly extracted and demultiplexed by the demultiplexer-side low-pass filter circuit 45. . In the present embodiment, each of the high-pass filter circuit 46 and the demultiplexer-side low-pass filter circuit 45 is configured by an analog filter circuit (here, an LC filter circuit that is an analog passive filter circuit).

The demultiplexed reception signal of each frequency band from the demultiplexing circuit 44 is switched between the transmission signal of each frequency band toward the antenna 39 by the corresponding switch circuits 42A and 42B. The switch circuits 42A and 42B transmit the low-frequency side demultiplexed reception signal and the high-frequency side reception signal to the reception circuit (reception units 35A / 35B and demodulation units 36A / 36B) side of the mobile phone (FIG. 1: wireless telephone communication device) 1. Output terminals RX1 and RX2 for outputting wave reception signals, respectively, and transmission circuits (modulation units 32A / 32B and transmission units 33A / 33) of the mobile phone 1.
B), a transmission input terminal TX1 to which a transmission signal is input.
TX2, and reception output terminals RX1 and RX2 and transmission input terminals TX1 and TX for the antenna-side input / output unit ANT.
2 is switched.

Then, corresponding to the high-frequency side switch circuit 42B of the switch circuits 42A and 42B, a signal having a frequency equal to or higher than a predetermined frequency is obtained from the divided reception signal in the frequency band handled by the high-frequency side switch circuit 42B. An adjustment low-pass filter circuit 43 for reducing components is provided. The arrangement position of the adjustment low-pass filter circuit 43 is between the high-frequency side switch circuit 42B and the antenna 39. As shown in FIG. 2, each of the reception output terminals RX1 and RX2 receives a frequency band (FIG. 1) from each of the split reception signals (FIG. 10).
0: -δ1, -δ2) are connected to the bandpass filter circuits 40A and 40B for extracting the used frequency. The adjustment low-pass filter circuit 43 is provided with a pass band of the band pass filter circuit 40B for use frequency extraction corresponding to the high-frequency side switch circuit 42B (FIG. 10: −δ).
It has a cut-off frequency fc on the higher frequency side than 2).

The low-frequency side transmission signal input from the first transmission unit 33A through the transmission input terminal TX1 is used to reduce the high-frequency side background noise by the first transmission filter circuit 41.
After being removed by A (configured by a low-pass filter circuit), the signal is input to the switch circuit 42A. The low-frequency side transmission signal input from the second transmission unit 33B via the transmission input terminal TX2 is also subjected to a high-frequency side background noise removal by the second transmission filter circuit 41B having the same configuration, and then the switch circuit 42B, the second transmission filter circuit 41B is omitted in this embodiment (see FIG. 3).

Demultiplexing circuit 44 and plural switch circuits 42
A and 42B are, as shown in FIG. 4 and FIG. 5, a laminated body 80 in which the component parts are formed by laminating a circuit pattern and a dielectric layer.
, The inner layer is embedded in the circuit pattern. On the surface of the laminate 80, the antenna-side input / output terminal ANT and the reception output terminals RX1 and RX2 and the transmission input terminals TX1 and TX of the switch circuits 42A and 42B are provided.
2 are exposed. As a result, the number of components is reduced and component mounting is simplified. In the present embodiment, the adjustment low-pass filter circuit 43 is also integrated with the laminate 80 (specifically, the demultiplexing circuit 4
4, the number of components is further reduced and the circuit configuration is made more compact.

FIG. 3 is a circuit diagram showing details of the high-frequency signal processing circuit 2. In the demultiplexing circuit 44, the demultiplexing circuit side low-pass filter circuit 45 includes a capacitor C107, which is a main part of the primary low-pass filter circuit function, and a capacitor C108 and a coil L106 inserted in parallel with the capacitor C107. The capacitor C108 and the coil L106 constitute an LC resonance type band-eliminating filter circuit that generates an attenuation pole on the higher frequency side than the pass band (that is, sharpens the attenuation characteristic of the filter circuit). In the present embodiment, it is necessary to separate the first use frequency band and the second use frequency band around 1 GHz, and the capacitances of the capacitors C107 and C108 and the inductance of the coil L106 also have cut-off frequencies and It is adjusted to obtain the attenuation pole position. Basically, the capacitance of the capacitor C107 is adjusted so that the impedance is sufficiently high in the pass band and sufficiently low on the high frequency side. Conversely, the coil L106 sufficiently performs the function of adjusting the attenuation pole,
In addition, the inductance is adjusted so that the impedance in the pass band is sufficiently low and the impedance is sufficiently high on the higher frequency side so as not to unnecessarily attenuate the signal in the pass band.

On the other hand, the high-pass filter circuit 46 includes a capacitor C20 which is a main part of the primary high-pass filter circuit function.
7, C208 and a capacitor C209 inserted in parallel with C208
And a coil L206. Capacitor C209 and coil L
206 is an L that causes an attenuation pole on the lower frequency side of the pass band.
A C resonance type band pass filter circuit is configured. The capacitance of the capacitors C207 and C208 is adjusted so that the impedance is sufficiently low in the pass band and sufficiently high on the lower frequency side. On the other hand, the coil L106 is
The inductance is adjusted so that the impedance is sufficiently high in the pass band and sufficiently low on the lower frequency side.

The first transmission filter circuit 41A (and the second transmission filter circuit 41B) also includes capacitors C101 to C101.
C105 (C201 to C205: FIG. 11) and coils L101 and L102
(L201, L202: FIG. 11), the configuration is the same as that of the low-pass filter circuit 45 on the branching circuit side. I have.

Next, since the first switch circuit 42A and the second switch circuit 42B have basically the same configuration, the first switch circuit 42A will be described as a representative example (see FIG. There are two switch circuits 42
A, 42B, capacitors C1, C2, C3, C4, C5
Are the capacitors C6, C7, C8, C9, C10 and the coil L
1, L104 corresponds to coils L3 and L204, diodes D1 and D2 correspond to diodes D3 and D4, and resistor R1 corresponds to resistor R2).

The first switch circuit 42A is basically configured as a diode switch having a built-in strip line resonator. The main part of the switch function is performed by the antenna input / output terminal AN when viewed from the transmission input terminal TX1.
T and the branch point A of the path toward the reception output terminal RX1
The switching diode D1 arranged above
And a coil L104 and a resonance diode D2 that constitute a stripline resonator and are disposed below the branch point A on the reception output terminal RX1 side.

The switching diode D1 is, for example, PI
It is composed of N diodes and functions as a high-frequency variable resistance element according to the applied level of a forward bias voltage. That is, the switch control signal terminals VC1, VC
2 (VC3, VC4 in the second switch circuit 42B),
When a signal voltage difference is given so that the VC1 side becomes a high voltage,
The switching diode D1 is in a low impedance state with respect to the high frequency, and the transmission input signal is allowed to flow to the antenna side input / output terminal ANT. At this time, VC1 and VC2 are set so that the junction capacitance of the resonance diode D2 becomes a value suitable for the resonance condition of the stripline resonator.
By adjusting the signal voltage difference between the input and output terminals, the impedance of the branch point A is increased by the operation of the resonator, and the transmission input signal is received by the reception output terminal RX1 (RX in the second switch circuit 42B).
2) It is prevented from flowing to the side. Note that the terminal VC2 may be grounded.

On the other hand, if the signal voltage difference between VC1 and VC2 is made sufficiently small, the switching diode D1 will be in a high impedance state with respect to the high frequency, and the transmission input signal will be prevented from flowing to the antenna input / output terminal ANT. At this time, since the strip line resonator including the coil L104 and the resonance diode D2 does not operate, the impedance at the branch point A decreases. As a result, the reception input signal from the antenna side input / output terminal ANT is allowed to flow to the reception output terminal RX1 via the branch point A. Thus, by adjusting the signal voltage difference between VC1 and VC2, the connection between the reception output unit RX and the transmission input unit TX1 with respect to the antenna-side input / output unit ANT can be switched.

The coil L provided on the terminal VC1 side
A choke coil 1 prevents a transmission input signal from flowing back to the VC1 side. Capacitors C2 and C5 are connected to terminal V
It is for removing noise of the switch control signal input to C1 and VC2. Further, capacitors C1, C3 and C4
Are for removing a DC component, but they are mounted on the surface of the laminated body 80 (or provided outside the laminated body 80, although they are inferior in the effect of saving space and reducing the number of assembling steps). ) Is also possible. On the other hand, the resistor R1
Since the change in resistance of the switching diode D1 is determined by the forward current value, the switch diode D1 is provided as an adjusting resistor for adapting the forward current value to the switching operation.

As shown in FIG. 5, the circuit elements shown in FIG. 3, except for a diode which is a semiconductor device, are formed in a laminate 80 by circuit patterns 53 to 55 composed of conductive layers (the inner layer is formed). ) Can be. For example, the resistor 55 can be formed by a meandering elongated conductor layer pattern as shown in FIG. As shown in FIG. 7, the capacitor 54 can be formed by facing electrode plates 55a and 55b with the dielectric layer 50 interposed therebetween. Further, the coil 53
Is a winding pattern 53a extending over a plurality of dielectric layers 50.
Are connected by interlayer vias 59. On the other hand,
The dielectric layer 50 is made of, for example, a ceramic such as a glass ceramic made of lead borosilicate glass and alumina. The laminate 80 is manufactured by a method in which a circuit pattern is printed on a ceramic green sheet as a raw material of the dielectric layer 50 by using a conductive paste to form a thick film, laminated, and fired. Since these are well-known techniques, detailed description will be omitted.

Elements that are difficult to realize by forming a circuit pattern by thick-film printing, such as a semiconductor device such as a diode, a large-capacity capacitor, or a resistance element having a high resistance value, as shown in FIG. (Alternatively, the external device 51 may be mounted on the main board separately from the stacked body 80, but may be mounted on the main board separately from the stacked body 80. Is desirably integrated with the laminate 80 as described above).

In this embodiment, as shown in FIG. 5, a coil 53 (L
201), the electrode plate 56 facing the coil 53 is provided on at least one side in the laminating direction of the laminated body 80, in this embodiment, on both sides. And those coils 5
A capacitor 54 (C11 to C13) constituting a component of the low-pass filter circuit 43 for adjustment is incorporated in the dielectric layer 50 located between the third electrode 3 and the electrode plate 56. In recent years, as for the laminated body 80 for a high frequency switch, the unification of the impedance has been promoted as a part of the integration of component standards, and the laminated body 8
It has become mandatory to match the overall impedance level of 0 to a specified value (for example, 50Ω). However, depending on the line width of the circuit pattern and the positional relationship between the fabricated element and the grounding electrode plate, parasitic capacitance may occur and impedance may increase. In particular, a high-capacitance parasitic capacitance is likely to occur between the coil 53 where the conductor distribution area tends to be large and the large-area electrode plate 56 used for grounding or the like. Therefore, in order to adjust the above impedance to a specified value, it is necessary to set the distance between the coil 53 and the electrode plate 56 to a certain value or more (for example, 150 μm or more) in order to reduce the parasitic capacitance. In this case, the dielectric layer 50 between the coil 53 and the electrode plate 56 becomes a dead space as it is, and
There is a problem that the size of 0 becomes large. this is,
This is clearly disadvantageous in the field of portable telephones, which tend to be miniaturized in recent years. Therefore, the adjustment low-pass filter circuit 4
If the capacitor 54 constituting the third component is incorporated in the dielectric layer 50, the occurrence of dead space is eliminated, and the size of the stacked body 80 can be reduced.

Returning to FIG. 2, the reception output terminals RX1 and RX2
The bandpass filter circuits 40A and 40B for use frequency extraction connected to are both configured as narrow band filter circuits including a surface acoustic wave resonator in the present embodiment. FIG. 9 shows an example of such a filter circuit, in which an interdigital transducer type (hereinafter abbreviated as IDT type) resonator is used as a surface acoustic wave resonator. The IDT resonator utilizes a resonance phenomenon caused by surface acoustic waves propagating while being reflected and transmitted over a large number of pairs of interdigital transducers formed on a piezoelectric ceramic plate. The bandpass filter circuit of the above shows a very sharp narrow band pass characteristic near the resonance frequency. Since the surface acoustic wave resonator and the filter circuit itself shown in FIG. 9 including the same are known in the literature (Proc. IEEE, 64, 5, p. 685 (1976)), a more detailed description will be given. Description is omitted. Note that, instead of the IDT resonator, a narrow band filter circuit using a cavity resonator may be used.

The bandpass filter circuit 40A for use frequency extraction constituted by such a narrow band filter circuit,
By 40B, as shown in FIGS. 10 and 10, a signal of a used frequency band having a narrow bandwidth δ1 or δ2 is extracted from each of the demultiplexed reception signals output to the reception output terminals RX1 and RX2. In the present embodiment, the second use frequency band on the high frequency side is a high frequency band of 1 GHz or more, the allocated bandwidth is very narrow, and the narrow band filter circuit used is also in the high frequency band of 1 GHz or more. The pass band width must be within the range of about 50 to 75 MHz. (If the pass band width is 50 MHz or less, it becomes difficult to extract a signal in the used frequency band with a margin.
Above 5 MHz leads to an increase in noise). But,
A narrow band filter using a surface acoustic wave of a piezoelectric ceramic may not be able to sufficiently remove a signal component (residual signal component) on a higher frequency side than a used frequency band in a divided signal. It is easy for the waveform of the band extraction signal to deteriorate and the noise to increase, leading to a decrease in communication quality.

Therefore, as shown in FIG. 10, the cut-off frequency fc (1.8 GHz band) set by the adjustment low-pass filter circuit 43 to at least twice the pass frequency (center value) of the band-pass filter circuit 40B. In the case where is used, after removing the signal component of 3.6 GHz or more in advance, and extracting the signal of the working frequency band as shown in the following, the above-mentioned problem can be effectively solved. .

Next, as shown in FIG. 3, the adjusting low-pass filter circuit 43 includes capacitors C11 to C13 and a coil L.
The configuration 200 is the same as that of the low-pass filter circuit 45 on the branching circuit side. Such an adjustment low-pass filter circuit 43 includes the high-frequency side switch circuit 42B and the antenna 3
9 (FIG. 2).
The transmission signal from 3B (FIG. 1) also passes through the adjustment low-pass filter circuit 43. Therefore, the adjustment low-pass filter circuit 43 also has the function of the first transmission filter 41A on the first transmission section 33A (FIG. 1) side. Therefore, in the present embodiment, attenuation between the high-frequency side component of the transmission signal and the transmission input terminal TX2 for inputting the transmission signal toward the high-frequency side switch circuit 42B is reduced. Applying a low-pass filter (that is, FIG. 2
The second transmission filter 41B) shown by a virtual line is not provided, and the number of parts is reduced.

By arranging the adjustment low-pass filter circuit 43 close to the antenna 39 as described above,
As already described in the section of "Means for Solving the Problems", an effect of making it difficult for the noise picked up by the wiring and the like in the device to remain in the transmission signal is obtained.

The adjustment low-pass filter circuit 43 is provided between the antenna 39 and the high-pass filter 46 (the antenna-side input / output terminal ANT and the high-pass filter 46).
(Or between the antenna-side input / output terminal ANT and the antenna 39 outside the laminate 80), but as in the above-described embodiment, the high-frequency side switch circuit 42B and the high-pass filter 46 The following effects are produced by providing between them. That is, the branching circuit side low-pass filter circuit 45 and the high-pass filter circuit 46
Is an LC filter designed for demultiplexing, circuit constants are designed so that overlapping of passbands is minimized. In other words, in FIG. 3, the pass characteristic to the ground side in the branching circuit side low-pass filter circuit 45 is represented by:
The constants of each coil and capacitor are determined so that the passing characteristic of the high-pass filter circuit 46 to the switch 42B side is substantially equal. This means that the input impedances of the respective filter circuits 45 and 46 are substantially equal to each other as viewed from the branch point JA to the two filter circuits 45 and 46.

Here, if the adjustment low-pass filter circuit 43 is disposed between the high-pass filter circuit 46 and the switch 42B as shown in FIG. 3, the influence of the impedance change due to the addition of the adjustment low-pass filter circuit 43 will be eliminated. It becomes difficult to reach the branch point JA. As a result, the levels of the demultiplexed signals directed to the demultiplexer-side low-pass filter circuit 45 and the high-pass filter circuit 46 can be made uniform, and the problem that the sensitivity varies depending on the band used is less likely to occur. On the other hand, the adjustment low-pass filter circuit 43
Is disposed between the high-pass filter circuit 46 and the antenna 39, the influence of the impedance change thereby greatly affects the branch point JA. Therefore, it is necessary to separately change the circuit specifications for impedance adjustment.

Another characteristic of FIG. 3 is that the adjustment low-pass filter circuit 43 and the high-pass filter circuit 46 are directly connected without any intervening other circuit elements. By doing so, the wiring distance between the two circuits 43 and 46 is reduced, and the effect of the wiring on the filter characteristics of the parasitic capacitance and the parasitic inductance can be greatly reduced.

As described above, the adjustment low-pass filter circuit 4
The component 3 is internally layered in the form of a component pattern incorporated in the circuit pattern in the laminate 80 shown in FIGS. Further, the adjustment low-pass filter circuit 4
3 and the high-pass filter circuit 46 are also provided in the above-described laminated body 80.
The inner layer is formed in the form of a component pattern incorporated in the circuit pattern. In this case, as described above, by connecting the low-pass filter circuit 43 for adjustment and the high-pass filter circuit 46 directly, it is possible to share a part of the component pattern of the low-pass filter circuit for adjustment and the high-pass filter circuit. This can contribute to the compactness and high integration of the stacked body 80.

When the two filter circuits 45 and 46 are composed of LC filters as described above, the characteristic of the cascade connection between the LC low-pass filter and the LC high-pass filter is that the capacitor C12 included in the adjustment low-pass filter circuit 45 has , A capacitor C207 included in the high-pass filter circuit 46 is connected in series adjacent to each other. When this is incorporated in the laminate 80, as shown in FIG.
The pattern of the electrode plates E4 and E5 on the adjacent side of 207 is a common electrode plate pattern EB located between the two dielectric layers 50, while the remaining electrode plate patterns E6 and E3 are May be disposed so as to face the common electrode plate pattern EB. By doing so, the number of electrodes of the capacitor that consumes a large amount of substrate area can be reduced, and the effect of making the laminate 80 compact or highly integrated can be enhanced. In the present embodiment, the electrode plates E1 to E4 of the two capacitors C208 and C207 connected in series included in the high-pass filter circuit 46 are also set to E.
2 and E3 are similarly shared in the form of a single electrode plate EA.

In FIG. 3, the transmission input terminal TX2
An element for adjusting the input impedance of the transmission input terminal TX2, such as a coil or a capacitor, can be provided between the high frequency side switch circuit 42B and the high frequency side switch circuit 42B. On the other hand,
As shown in FIG. 11, in order to further increase the attenuation on the high frequency side of the transmission signal, the transmission side low-pass filter circuit 41B is also provided between the transmission input terminal TX2 and the high band side switch circuit 42B.
Can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a mobile phone showing one embodiment of a wireless telephone communication device of the present invention.

FIG. 2 is a block diagram of the high-frequency signal processing circuit.

FIG. 3 is a circuit diagram showing details of the high-frequency signal processing circuit of FIG. 2;

FIG. 4 is a perspective view showing an example of the appearance of a high-frequency signal processing circuit configured as a laminate.

FIG. 5 is a schematic cross-sectional view illustrating an example of the structure of a laminate.

FIG. 6 is a schematic view showing a state of forming a resistor in a laminate.

FIG. 7 is a schematic view showing a manner of forming a capacitor.

FIG. 8 is a schematic view showing a manner of forming a coil.

FIG. 9 is a diagram showing an example of a narrow-band filter circuit including a surface acoustic wave resonator.

FIG. 10 is a diagram illustrating the operation of the high-frequency signal processing circuit according to the present invention.

FIG. 11 is a diagram showing a modification of the circuit in FIG. 3;

FIG. 12 is a view for explaining the concept of sharing an electrode plate of a capacitor connected in series between a cascade-connected LC low-pass filter and an LC high-pass filter.

[Explanation of symbols]

1 Digital cellular phone (wireless telephone communication device) 32A, 32B Modulation unit (transmission circuit) 33A, 33B Transmission unit (transmission circuit) 35A, 35B Receiver (reception circuit) 36A, 36B Demodulation unit (reception circuit) 39 Antenna 40A, 40B Bandpass filter circuits for use frequency extraction 41A, 41B Input low-pass filter circuits 42A, 42B Switch circuit 43 Adjustment low-pass filter circuit 44 Demultiplexer circuit 46 High-pass filter circuit 50 Dielectric layer 56 Electrode plate 80 Laminated body RX1, RX2 Reception Output terminal TX1, TX2 Transmission input terminal ANT Antenna-side input / output terminal C12 Capacitor C207 Capacitor E4, E5 Electrode plate EB Common electrode plate pattern E6, E3 Remaining electrode plate pattern

Claims (10)

[Claims] 1. A high-frequency signal processing circuit used in a wireless telephone communication device corresponding to a plurality of frequency bands, which is used by being connected to an antenna, and is commonly used for input / output of an antenna reception signal and an antenna transmission signal. An antenna-side input / output terminal, a branching circuit that is connected to the antenna-side input / output terminal and that includes a high-pass filter circuit, and that branches a reception signal into a transmission / reception circuit system that individually processes the plurality of frequency bands; A receiving circuit that is provided between the branching circuit and a transmitting / receiving circuit corresponding to each of the plurality of frequency bands and outputs a branching reception signal from the branching circuit to a receiving circuit side of the wireless telephone communication device; A plurality of switches for switching connection between an output terminal and a transmission input terminal to which a transmission signal from a transmission circuit of the wireless telephone communication device is input, with respect to the antenna-side input / output terminal. And a switch circuit (hereinafter, referred to as a high-frequency switch circuit) that handles a signal demultiplexed by the high-pass filter circuit in the demultiplexer circuit, among the plurality of switch circuits, and an antenna-side input / output terminal. A low-pass filter circuit for adjusting, from a signal in a frequency band handled by the high-frequency side switch circuit, a signal component on a higher frequency side than a used frequency band. Processing circuit. 2. The high-frequency signal processing circuit according to claim 1, wherein the adjustment low-pass filter circuit is provided between the high-frequency side switch circuit and the high-pass filter. 3. The high-frequency signal processing circuit according to claim 2, wherein the adjustment low-pass filter circuit and the high-pass filter circuit are directly connected without interposing other circuit elements. 4. A laminated body in which a circuit pattern and a dielectric layer are laminated, wherein components of the branching circuit and the plurality of switch circuits are formed in an inner layer in the form of a component pattern constituting the circuit pattern. 4. The high-frequency signal processing circuit according to claim 1, wherein the antenna-side input / output terminal and a reception output terminal and a transmission input terminal of each switch circuit are exposed on a surface of the laminate. 5. The high-frequency device according to claim 1, wherein the component parts of the adjustment low-pass filter circuit are formed in the laminated body in the form of a component pattern constituting the circuit pattern. Signal processing circuit. 6. The adjusting low-pass filter circuit and the high-pass filter circuit, which are directly connected without passing through another circuit element, are internally layered in the laminate in a form incorporated in the circuit pattern, and 6. The high-frequency signal processing circuit according to claim 5, wherein a part of a component pattern of the adjustment low-pass filter circuit and a part of the component pattern of the high-pass filter circuit are shared. 7. A capacitor included in the adjustment low-pass filter circuit and a capacitor included in the high-pass filter circuit are connected in series adjacent to each other, and the electrode plate pattern on the adjacent side of the capacitors is
7. The high-frequency device according to claim 6, wherein the common electrode plate pattern is located between two dielectric layers, and the remaining electrode plate pattern is arranged to face the common electrode plate pattern with each dielectric layer interposed therebetween. Signal processing circuit. 8. A low-pass filter that attenuates a high-frequency component of the transmission signal between the high-frequency side switch circuit and a transmission input terminal for inputting a transmission signal toward the high-frequency side switch circuit. The high-frequency signal processing circuit according to any one of claims 1 to 7, wherein the circuit is not provided. 9. The high-frequency signal processing circuit according to claim 1, an antenna connected to the antenna-side input / output terminal of the high-frequency signal processing circuit, and a reception output terminal. A band-pass filter circuit for extracting a used frequency band from the divided reception signal, a reception circuit connected to the reception output terminal, and a transmission circuit connected to the transmission input terminal. The adjustment low-pass filter circuit has a higher frequency side than a pass band of the operating frequency extracting band-pass filter circuit (hereinafter, referred to as a high-frequency operating frequency extracting band-pass filter circuit) corresponding to the high-frequency side switch circuit. A wireless telephone communication device having a cut-off frequency. 10. The bandpass filter circuit for extracting a high-frequency-side use frequency, which is 50 to 7 in a frequency range of 1 GHz or more.
The wireless telephone communication device according to claim 9, wherein the wireless telephone communication device is a narrow-band filter circuit including a surface acoustic wave resonator having a pass bandwidth of 5 MHz.