ES2287964T3 - SWITCHING CIRCUIT AND COMPOSITE SWITCHING DEVICE. - Google Patents

Abstract

A composite switching circuit (30) for alternating and electrically connecting a first circuit (Tx) to a third circuit (ANT) or a second circuit (Rx) to a third circuit (ANT). The composite switching circuit (30) incorporates a low pass filter (LPF) circuit in the switching circuit part of the composite switching circuit (30) so as to create a highly symmetrical circuit configuration. The composite switching circuit (30) is disposed on a plurality of dielectric substrates (22-28) of an integral multilayer body (2) to provide a miniaturized composite switching device. Since the composite switching device that includes the composite switching circuit (30) with a symmetrical circuit configuration shows low insertion loss and high performance over a wide frequency range, the composite switching device is advantageously used to form a part of a radio transceiver such as a cellular radiotelephone.

Description

Switching circuit and device Compound switching

Background of the invention

The present invention relates to a circuit switching, and particularly to a switching circuit compound comprising a diode switching circuit that incorporates a low pass filter circuit to be used as a high frequency switching circuit of a digital cellular radiotelephone, etc., with a view to switching alternatively transmission paths to transmit or receive Communications signals The present invention also relates to a switching device composed of a multilayer body integral that includes the compound switching circuit.

A switching circuit for a radiotelephone digital cell phone, etc., is used to connect alternately  a receiver circuit to an antenna or a transmitter circuit to the antenna. In a radiotelephone that uses a system with diversity of reception, the switching circuit also connects alternatively a receiver circuit to a first antenna or the receiver circuit to a second antenna. Probably in one base station for a radiocommunication system that uses a system with transmission diversity, the switching circuit It is also used to alternately connect a circuit transmitter to a first antenna or the transmitter circuit to a second antenna

On a radiotelephone that has an external port to connect a car power supply, etc., the circuit switching is also used to switch a path to a internal circuit and a path to the external port. In addition, the switching circuit is used to switch a plurality of base station channels for the system Radiocommunications

Fig. 11 is a schematic diagram of a circuit showing a conventional switching circuit given to know in published Japanese patent no. 6-197040. In Fig. 11, the switching circuit alternatively connect a Tx transmitter circuit to an ANT antenna or an Rx receiver circuit to the ANT antenna. The transmitter circuit Tx is connected to an anode of a first diode D101 through a first capacitor C101. A cathode of the first diode D101 is connected to the ANT antenna through a third C103 capacitor. The antenna ANT is also connected to an Rx receiver circuit through a third capacitor C103, a second transmission line SL2 and a fourth capacitor C104 connected in series. An anode of the first diode D101 is grounded through a first line of SL1 transmission and a second C102 capacitor connected in series. In addition, a control circuit T1 is connected to a formed node between the first transmission line SL1 and the second capacitor C102 through a resistor R101. An anode of a second diode D102 is connected to a node formed between the second line of transmission SL2 and the fourth capacitor C104, and a cathode thereof It is grounded. Transmission lines and some of the capacitors are arranged on a plurality of substrates of a dielectric laminated body, and diodes, resistance and rest of the capacitors are mounted on a surface upper laminated body.

When using the switching circuit a filtering circuit, switching circuit and circuit filtered form separately and then connect between yes. For this reason, an extensive mounting area is necessary, and requires an additional circuit for the adaptation of impedances

To solve the previous problem, the document EP 0 785 590 A discloses a composite device that includes a switching circuit and a filtering circuit. This device presents the characteristics included in the first part of the claim 1. An equivalent circuit is shown in Fig. 12 of the composite device. In Fig. 12, by means of a block shown in dashed lines a circuit part of filtered out. The filtering circuit is positioned to interconnect a Tx transmitter circuit and switching circuit. In Fig. 13 an equivalent circuit is shown when the transmitter circuit Tx It is electrically connected to the ANT antenna. In the circuit equivalent, diodes D201 and D202 are not shown since the they are in their position by the DC current and in a Low impedance state to form short circuits.

As can be seen from Fig. 13, a conventional circuit formed simply by the filtering circuit connection to switching circuit lacks of symmetry in the configuration of the circuit to present some sufficient frequency characteristics only in one band narrow frequency. A band switching circuit narrow presents a reduced performance considering the full use of the assigned frequency band for a communications system, and is deficient in terms of productivity due to product variability.

Objective and summary of the invention

Therefore, one of the objectives of the present invention is to provide a switching circuit Composite, broadband, with high configuration symmetry of the circuit and a compound switching device miniaturized of an integral multilayer structure that includes the Compound switching circuit.

This objective is achieved with the circuit defined in claim 1.

As a result of intense research carried out taking into account the previous objectives, the inventors have observed that the symmetry in the configuration of the circuit can be increased by providing a filtering circuit low-pass between a diode and a transmission line in a switching circuit instead of simply connecting the low pass filtering circuit to the circuit switching, thereby reducing the level of loss of insertion and guaranteeing a high performance of the circuit switching in a wider frequency band compared with conventionally known switching circuits.

The subordinate claims are set forth Preferred embodiments of the invention.

Brief description of the drawings

Fig. 1 is a perspective view that shows a switching device composed of the present invention;

Fig. 2 is a perspective view that shows the respective substrates that make up the body integral multilayer of the composite switching device shown in Fig. 1;

Fig. 3 is a schematic diagram of a circuit showing an equivalent circuit of a circuit radio transceiver that includes a circuit compound switching of the present invention;

Fig. 4 is a schematic diagram of a circuit showing an equivalent circuit of Fig. 3, in the which the transmitter circuit Tx is electrically connected to the ANT antenna;

Fig. 5 is a schematic diagram of a circuit showing an equivalent circuit of a circuit radio transceiver that includes another circuit of compound switching of the present invention;

Fig. 6A is a graph showing the loss of insertion at a frequency of up to 5.5 GHz measured on the composite switching device of the present invention;

Fig. 6B is a graph showing the band of enlarged passage of Fig. 6A;

Fig. 7 is a schematic diagram of a circuit showing an equivalent circuit of the filtering part  low-pass switching circuit composed of the present invention;

Fig. 8 is a perspective view that shows the respective substrates that constitute a body integral multilayer in which another circuit of compound switching of the present invention;

Fig. 9 is a schematic diagram of a circuit showing an equivalent circuit of a circuit transceiver that includes the composite switching circuit disposed on the integral multilayer body of Fig. 8;

Fig. 10 is a schematic diagram of a circuit that shows a partial equivalent circuit of still another composite switching circuit of the present invention;

Fig. 11 is a schematic diagram of a circuit showing an equivalent circuit of a circuit conventional switching;

Fig. 12 is a schematic diagram of a circuit that shows an equivalent circuit of another circuit of conventional switching; Y

Fig. 13 is a schematic diagram of a circuit showing an equivalent circuit of the circuit conventional switching of Fig. 12, in which the circuit Tx transmitter is electrically connected to the ANT antenna.

Description of the preferred embodiments

As summarized above, the Compound switching circuit of the present invention is a switching circuit incorporating a filtering circuit low-pass, and it can be operated to alternately and electrically connect a first circuit to a third circuit or a second circuit to the third circuit. In a of the preferred embodiments, the switching circuit compound can be a switching circuit of an antenna in the which the first circuit is a transmitter circuit, the second circuit is a receiver circuit, and the third circuit is a antenna. The present invention will be described in more detail with with respect to said switching circuit of an antenna. However, it should be considered as illustrative of one of the various preferred embodiments of the present invention.

In the present invention, a circuit of switching incorporates a circuit corresponding to a circuit of low-pass filtering to form a single circuit of compound switching The compound switching circuit can be arranged on a plurality of dielectric substrates for form a miniaturized composite switching device of a integral multilayer body.

An equivalent circuit is shown in Fig. 3 of a radio transceiver circuit that includes a Compound switching circuit of the present invention. At equivalent circuit, the first circuit is a transmitter circuit Tx, the second circuit is an Rx receiver circuit, and the third circuit is an ANT antenna. A compound switching circuit 30 inside a block indicated by a dashed line It includes a first track that interconnects the Tx transmitter circuit and the ANT antenna and a second path that interconnects the circuit Rx receiver and ANT antenna. The first path includes a first diode D1 and a first transmission line L1, being connected a first lateral part of the first diode D1 to the antenna ANT and being connected a first side part of the first line of transmission L1 to a node between a second side part of the first diode D1 and the transmitter circuit Tx in a configuration in derivation. The second track includes a second transmission line L2 and a second diode D2, a first part being connected side of the second transmission line L2 to the ANT antenna and a first lateral part of the second diode D2 being connected to a node between a second side part of the second line of L2 transmission and the Rx receiver circuit in a configuration in derivation.

The filtering circuit LPF low pass inside an indicated block with a dashed line is incorporated into the circuit of switching to interconnect the second side part of the first diode D1 and the first side part of the first line of transmission connected in branch L1, to form in this way the Compound switching circuit of the present invention. Such as shown in Fig. 3, the filtering circuit LPF low-pass usually comprises a line of L3 transmission, a C4 capacitor in parallel with the line of L3 transmission and C2 and C3 capacitors that form each of them a way of derivation to earth.

In addition, as seen from Fig. 3, a second side part of the transmission line L1 is grounded through a capacitor C14, and a first CONT1 control circuit is connected bypass between the first transmission line L1 and capacitor C14 through a resistance R1. CONT1 can be omitted, and if omitted, the first Transmission line L1 can be connected directly to ground. In addition, a second lateral part of the second diode D2 is grounded through a capacitor C1, and a second CONT2 control circuit is connected bypass between the second diode D2 and capacitor C1 through a resistor R2. The control circuits control whether the Tx transmitter circuit (first circuit) or the receiver circuit Rx (second circuit) is electrically connected to the ANT antenna (third circuit) polarizing diodes D1 and D2. To each input / output terminal of the Tx transmitter circuit, the Rx receiver circuit and the antenna ANT, a DC, C11, C12 or C13 suppression capacitor is connected to let only high signals pass through it frequency.

In the present invention, the circuit of low pass filtering is not simply connected a switching circuit, but is incorporated into the circuit switching, more specifically, is incorporated between the second side part of the first diode D1 and the first side part of the first transmission line connected at branch L1. In Fig. 4 an equivalent circuit of Fig. 3 is shown when the circuit  Tx transmitter is electrically connected to the ANT antenna. In the Fig. 4, diodes D1 and D2 are not shown since they are found in a state of high conduction, low impedance, for form short circuits

As seen from Fig. 4, the Compound switching circuit of the present invention is highly symmetric in terms of circuit configuration. TO know, the transmitter circuit Tx, the capacitor C11, the line of transmission L1 and capacitor C14 are positioned symmetrically with the ANT antenna, the C13 capacitor, the line of transmission L2 and capacitor C1 (C12), respectively, with with respect to the low pass filter circuit central. With such symmetry in the configuration of the circuit, the composite switching circuit of the present invention has a lower level of insertion loss and some sufficient characteristics in a wider frequency band in comparison with conventional switching circuits.

An equivalent circuit is shown in Fig. 5 of another composite switching circuit 50 of the present invention. The equivalent circuit of Fig. 5 is similar to that of the Fig. 3, although in it the first and second diodes D1 and D2 they are connected inversely with respect to the anode and cathode. When the Tx transmitter circuit is electrically connected to the ANT antenna, the circuit of Fig. 5 has the same circuit equivalent shown in Fig. 4. Namely, the circuit of Compound switching of Fig. 5 also shows high symmetry regarding the configuration of the circuit, and presents a lower level of insertion loss and features enough in a wider frequency band compared to conventional switching circuits.

It has been experimentally confirmed that the equivalent circuit of Fig. 3 has a lower level of loss insertion and satisfactory insulation compared to the equivalent circuit of Fig. 5.

Fig. 1 is a perspective view that shows a switching device composed of the present invention. The substrates are shown in perspective in Fig. 2 which constitute the integral multilayer body of the device Compound switching of Fig. 1, and in Fig. 3 a equivalent circuit of a compound switching circuit disposed on a plurality of dielectric substrates of the switching device composed of Figs. 1 and 2.

As seen from Fig. 1, the composite switching device comprises an element semiconductor 1 containing two diodes and a multilayer body integral 2 of a plurality of dielectric substrates. In the Figs. 1 and 2, the part indicating the electrodes is shown by a scratch

In Fig. 3, the switching circuit compound of the present invention comprises the elements contained inside block 30 indicated by a line of dashes, and the capacitors C11, C12, C13, C14 and the resistors R1 and R2 outside block 30 are elements external which can be formed on a circuit board in which is mounted the compound switching device, or is can be arranged on dielectric substrates or surface upper multilayer integral body.

As seen from Fig. 2, the switching device composed of the embodiment comprises a lower dielectric substrate 21, the substrates interiors 22 to 28 and an upper dielectric substrate 29.

On the upper surface of the substrate lower dielectric 21, a first ground electrode 31 is formed, from which conductive electrodes extend to connect to external electrodes T2, T7 and T8 on the surface side of the integral multilayer body 2.

On the upper surface of the substrate dielectric 22 laminated on the lower dielectric substrate 21, a capacitive electrode 41 is formed in opposition to the first electrode ground 31 to form capacitor C1. A conductive electrode extending from capacitive electrode 41 is connected to a external electrode T4. Although in this embodiment the capacitor C1 is formed inside the multilayer body integral, it can be formed externally, for example, on the upper surface of the upper dielectric substrate 29 or above the circuit board on which the device is mounted compound switching

On the dielectric substrate 22, they are laminated dielectric substrates 23 and 24 having electrodes that They form the transmission lines. A spiral linear electrode 11 in the dielectric substrate 23 is connected to a linear electrode coiled 12 on the dielectric substrate 24 through an electrode through hole 51 to form the transmission line L1. Two conductive electrodes extend from linear electrodes coiled 11 and 12 to connect respectively to the electrodes external T3 and T6. A spiral linear electrode 13 in the substrate dielectric 23 is connected to a spiral linear electrode 14 in the dielectric substrate 24 through a hole electrode intern 52 to form the transmission line L2. Two electrodes conductors extend from spiral linear electrodes 13 and 14 to connect respectively to the external electrodes T5 and T1

On the upper surface of a substrate dielectric 25 laminated on the dielectric substrate 24, has been formed a second ground electrode 32. Three electrodes conductors extend from the second ground electrode 32 to connect respectively to external electrodes T2, T7 and T8

On the dielectric substrate 25, it has been laminated a dielectric substrate 26. On the upper surface of the dielectric substrate 26, a capacitive electrode 42 is formed in opposition to the second ground electrode 32 to form the capacitor C2 of the low-pass filter circuit. Also on the dielectric substrate 26 an electrode is formed capacitive 43 as opposed to the second ground electrode 32 for form the capacitor C3 of the filtering circuit low pass From capacitive electrode 42, it extends a conductive electrode to connect to the electrode external T3.

On the upper surface of a substrate dielectric 27 a capacitive electrode 44 is formed in opposition to the capacitive electrode 42 of the dielectric substrate 26 to form the capacitor C4 of the low-pass filter circuit. The capacitive electrode 44 is connected to the capacitive electrode 43 in the dielectric substrate 26 through a through hole 53.

On the upper surface of the substrate dielectric 28, a spiral linear electrode 15 is formed which forms  the transmission line L3 of the filtering circuit low pass One end of the linear electrode in spiral is connected to the external electrode T3, and the end opposite is connected to capacitive electrodes 44 and 43 a through through holes 54 and 53.

On the upper surface of the substrate upper dielectric 29, configuration electrodes are formed 16 and 17. The configuration electrode 16 is connected to the hole through 54 on the dielectric substrate 28 through a hole through 55. The configuration electrode 17 serves as a mark. On the upper surface of the upper dielectric substrate 29, is additionally form configuration electrodes for connect to external electrodes T1, T4, T5 and T6.

A switching device occurred. composed with the previous construction using a material dielectric that had a dielectric constant of approximately 8. The dielectric material was achieved to adopt a form of sheet (dielectric substrates) by means of a scraper blade and respective configuration electrodes were formed on dielectric sheets by screen printing of a electrically conductive material such as Ag. Substrates dielectrics that had electrodes on them Printed settings were laminated, compressed and cooked to get an integrated multilayer body. After cooking, on the lateral surface and upper body surface integral multilayer external electrodes T1 to T8 were formed and The configuration electrodes. Finally the element semiconductor 1 containing the first and second diodes D1 and D2 were mounted on the upper surface of the integral multilayer body of so that the first diode D1 was connected to the electrode of configuration 16 and external electrodes T5, and the second diode D2 was connected to external electrodes T1 and T4, respectively, to obtain a switching device composed of the present invention of a size having a length / width of 4.5 mm / 3.2 mm and a thickness of 2 mm.

In the compound switching device obtained in this way, the filtering circuit low-pass comprising the capacitors C2, C3 and C4 and the transmission line L3 was inserted between the anode part of the first diode D1 and the first lateral part of the line of transmission connected in branch L1.

The radio transceiver circuit of Fig. 3 is obtained by connecting the transmitter circuit Tx to the external electrode T3 through capacitor C11, connecting the ANT antenna to external electrode T5 through capacitor C13, connecting the receiver circuit Rx to the external electrode T1 through of capacitor 12, connecting the first control circuit CONT1 to the external electrode T6 through resistor R1, connecting the capacitor C14 to the external electrode T6 to form a path to ground, and connecting the second control circuit CONT2 to the external electrode T4 through resistor R2.

In Fig. 6A the insertion loss is shown at a frequency of up to 5.5 GHz measured on the device Compound switching obtained above. In Fig. 6B, shows an enlarged representation of the pass band (0.5 to 1.5 GHz) of Fig. 6A. As can be best seen from the Fig. 6B, the composite switching device had a insertion loss of a value as low as 1 dB or smaller in a frequency range of 900 ± 250 MHz. Of this mode, the switching circuit composed of the form of preferred embodiment of the present invention is excellent in as for the minimization of insertion loss. Also how do I know can reduce geometric dimensions, only one  small space in the mounting of the switching device compound of the present invention on a circuit board, thereby reducing the size of a transceiver of radiocommunications such as a cellular radiotelephone. He Compound switching device of the present invention is used suitably in a frequency range of approximately 800 MHz to several gigabytes of hertz.

In the previous embodiment, the first and the second transmission lines L1 and L2 were arranged between the first ground electrode 31 and the second ground electrode 32, and a substantial part of the switching circuit element is disposes closer to the mounting surface than the part of the low pass filter circuit. With a construction of this type, the second ground electrode 32 that form the grounded capacitors C2 and C3 with the opposing capacitive electrodes 42 and 43 may have a part conductive, that is, the external electrode T2 in the form of previous embodiment, to connect to a ground terminal of a circuit board on which the device is mounted compound switching The external electrode T2 functions as a linear electrode which can be considered as coils L4 and L5, as shown by an equivalent circuit of the Fig. 7, connected to capacitors C2 and C3 in series. In a equivalent circuit of this type, harmonics can be reduced effectively through serial resonance between the capacitor C2 with coil L4, and capacitor C3 with coil L5

For this reason, in the present invention, it is preferable that the first and second transmission lines L1 and L2 are arranged between two ground electrodes, and that the low pass filtering circuit capacitor se form by means of the ground electrode on the lines of L1 and L2 transmission and capacitive electrode on and in opposition to the ground electrode. With such a construction, you can obtain a miniaturized composite switching device of a high performance.

In the previous embodiment, the lines of transmission L1 and L2 were formed by linear electrodes in spiral printed on two dielectric substrates successively adjacent. Getting the linear electrodes to be in spiral and partially overlapping on linear electrodes in the two dielectric substrates, the length was reduced of linear electrodes.

Fig. 8 is a perspective view that shows the respective substrates that constitute a body integral multilayer in which another circuit of Compound switching 90 of the present invention. In Fig. 9, shows an equivalent circuit that includes the circuit of Compound switching 90. The equivalent circuit of Fig. 9 is similar to that of Fig. 2, although a additional capacitor C5 between the filtering circuit low-pass and first transmission line connected at branch L1 to form a branch line at land. The capacitor C5 is formed by means of a first electrode of earth 31 on a dielectric substrate 21 and an electrode capacitive 45 on a dielectric substrate 22 which is connected to a T3 electrode. As the third to ninth substrates to from the bottom of Fig. 8 are respectively same as the dielectric substrates 23 to 29 of Fig. 2, in this case and in Fig. 8 the description of these substrates is omitted.

A switching device occurred. compound that included the previous compound switching circuit in the same way as described above, and it was confirmed that it presented the same performance as in the form of previous embodiment.

As shown in Fig. 10, instead of capacitor C5, an additional capacitor C6 can be connected. By incorporating the capacitor C5 shown in Fig. 9 or the capacitor C6 shown in Fig. 10, can be reduced effectively the linear length of the first transmission line L1.

As described above, according to the present invention, a switching circuit can be obtained composed of small dimensions, in which a low-pass filtering circuit, with a high performance. Additionally, a device can be obtained from miniaturized composite switching that includes the circuit Compound switching in the form of an integral multilayer body arranging the compound switching circuit on a plurality of dielectric substrates. Switching circuit compound and the compound switching device of the present invention have sufficient characteristics in a range wide frequency, a much smaller insertion loss and a considerable effect of harmonic suppression.

Although the present invention has been described in relationship with an operational composite switching circuit for alternatively connect the transmitter circuit to the antenna and the receiver circuit to the antenna, it should be understood that the circuits to be switched by the switching circuit compound of the present invention are not specifically limited to The mentioned circuits.

Claims (9)

1. Compound switching circuit (30) for alternatively and electrically connect a transmitter circuit (Tx) or a receiver circuit (Rx) to an antenna (ANT), comprising: a first way that interconnects the circuit transmitter (Tx) and antenna (ANT), the first path comprising a first diode (D1) and a first transmission line (L1), the first diode (D1) presenting a terminal connected to the antenna (ANT), presenting the first transmission line (L1) one of its ends connected to a node formed between the transmitter circuit (Tx) and the other terminal of the first diode (D1) and its other end grounded, a second way that interconnects the circuit receiver (Rx) and antenna (ANT), the second way comprising a second transmission line (L2) and a second diode (D2), being connected one end of the second transmission line (L2) to the antenna (ANT), presenting the second diode (D2) one of its terminals connected to a node formed between the other end of the second transmission line (L2) and the receiver circuit (Rx) and its another grounded terminal, and a filtering circuit low-pass (LPF) arranged on the first track and that It comprises a transmission line (L3) and capacitors, characterized in that the low-pass filtering circuit (LPF) interconnects said other terminal of the first diode (D1) and said one end of the first transmission line (L1). 2. Circuit according to claim 1, wherein said a terminal of the first diode is the anode thereof, and said A terminal of the second diode is its anode. 3. Circuit according to claim 1, wherein said a terminal of the first diode is the cathode thereof, and said A terminal of the second diode is its cathode. 4. Compound switching device that comprises the compound switching circuit (30) according to any  of claims 1 to 3 arranged on a plurality of dielectric substrates of an integral multilayer body (2), in the that at least the first transmission line (L1), the second transmission line (L2) and a part of the filtering circuit low-pass (LPF) are arranged on at least an inner dielectric substrate (22 to 28) in the multilayer body integral (2). 5. Device according to claim 4, in the that the first and second diodes (D1, D2) are arranged on an upper surface of the integral multilayer body (2). 6. Device according to claim 4 or 5, in the one that the first and the second transmission lines (L1, L2) arranged on interior dielectric substrates (22 to 28) in the integral multilayer body (2) are positioned between two ground electrodes (31, 32) arranged on substrates respective dielectrics (21, 25), and in which a capacitor (C2) of the low-pass filter circuit (LPF) by means of the aforementioned (32) between said two electrodes of land (31, 32) between which the first and second transmission lines (L1, L2) and an electrode (42) arranged on a dielectric substrate (26) positioned above said upper ground electrode (32) and in opposition to it. 7. Device according to claim 6, in the that the electrodes (32, 42) that form the plates of said capacitor (C2) of the low-pass filter circuit (LPF) are arranged respectively on substrates dielectrics (25, 26) positioned on the upper side of the first and second transmission lines (L1, L2) with respect to a Mounting surface of the composite switching device. 8. Device according to any of the claims 4 to 7, wherein the first and second lines of transmission (L1, L2) are formed by configurations of electrodes (11 to 14) spirally. 9. Device according to claim 2 or according any of claims 4 to 8 subordinate to the claim 2, wherein a control circuit (CONT2) is connected to the anode of the second diode (D2) and a voltage is applied between the anodes of the first and second diodes (D1, D2).