JP2005073199A - High-speed tuner antenna multiplexer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-speed tuner antenna multiplexer appropriate for spread spectrum communication or the like using frequency hopping, so that high-speed switching of a tuning frequency can be performed and one antenna can be concurrently shared among a plurality of high frequency channels having multi-frequency bands. <P>SOLUTION: The antenna multiplexer comprises a plurality of couplers each composed of 2-terminal (n) paired circuits (n≥1), one terminal of each of the plurality of couplers is commonly connected to the one antenna, and the other terminal is connected to a plurality of transmitters/receivers. A diode switch provided in each of 2-terminal (n) paired circuits is switched at high speed while being linked with a frequency hopping timing of a spread spectrum signal, an arbitrary serial resonance circuit is selected out of 2-terminal (n) paired circuits in accordance with a resonant frequency closest to the hopping frequency, and each of the plurality of transmitters/receivers is capable of using one antenna individually or concurrently with the other transmitter/receiver. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to sharing of multiple frequency bands in a communication antenna, and more particularly to high-speed tuning switching within a plurality of different frequency bands.

In the conventional example, there is a variable frequency band filter that includes one filter and obtains two different frequency band characteristics by switching the control voltage.
In FIG. 6, the variable frequency band filter includes two series resonant circuits of a capacitor C101 and a distributed constant line Z101 on the input terminal 101 side, and a capacitor C102 and a distributed constant line Z102 on the output terminal 102 side as parallel arms. The coils L103 and L105 are connected in parallel with each series resonance circuit, and the band-variable capacitors C103 and C104 are passed from the midpoint of the parallel arm of the band rejection filter having the resonance frequency of each series resonance circuit as the attenuation pole. Switching diodes D101 and D102 are respectively provided between the grounds. The frequency of the attenuation pole can be switched by turning on / off the control voltage Vctl applied to the anode side of each of the diodes D101 and D102 and connecting or disconnecting the capacitors C103 and C104 with respect to the respective series resonance circuits. It is a thing.

These prior arts relate to a filter used for a duplexer of a microwave radio communication device, and more particularly to a frequency band variable BEF (band rejection filter) that makes a pass band and a stop band variable. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 7-321509

In realizing a high-speed tuning antenna duplexer for simultaneously sharing a high-frequency channel signal having a plurality of frequency bands with a single communication antenna using a spread spectrum signal by frequency hopping as in the present invention, Such technical requirements need to be solved as a problem.
(1) As an example of the high-frequency antenna duplexer used in the system, there is one used in a time division multiplexing system in which high-frequency channel switching is performed by switching high-frequency relays at predetermined time intervals.
In order to realize multiplex communication having a plurality of high-frequency channels with one antenna by using time division (time slot), the high-frequency switching unit is a mechanical switch using a high-frequency coaxial relay or a high-speed electron using a pin diode. A circuit is constituted by a switch.
For example, when four high-frequency channels are provided for one antenna and each high-frequency channel is switched and shared in a predetermined time slot, when one high-frequency channel is selected, the other three high-frequency channels are opened. Since the state is set, the antenna is occupied only by the timing corresponding to the time slot of one selected high-frequency channel. However, since time division multiplexing is used, the occupation time of each high-frequency channel is limited to a predetermined time within the time division multiplexing time slot.
The problem here is that by switching the high frequency channel in synchronization with the time slot, the time of the other high frequency channel is occupied while the antenna is occupied at the time slot timing given to the selected high frequency channel. Since it is the slot timing, the antenna cannot be used.
Since the antenna cannot be shared at the same time, the antenna utilization efficiency is reduced to 1/4 in the case of four high-frequency channels. This is a problem that causes time constraints in the use of the antenna.
(2) A high-frequency antenna duplexer used for spread spectrum communication is used for a frequency division multiplex communication system or a frequency hopping spread spectrum communication system in which a high frequency band is divided into a predetermined number of frequencies.
High-frequency channel multiplexing, in which a plurality of high-frequency channels separated by a predetermined frequency bandwidth are arranged, is detuned at a frequency interval that does not cause frequency selection characteristics and interference between each high-frequency channel. A band-pass filter having such characteristics is provided, and the antenna is further shared.
A conventional bandpass filter that selects a frequency band of a high-frequency channel is, for example, a π-type filter having a cavity structure. On the other hand, since it is short-circuited, the antenna is reflected.
Thus, in the case of a system in which a bandpass filter having a π-type filter having a cavity structure is provided for four high-frequency channels and connected to one antenna, the passband of one selected high-frequency channel is selected. Since it is out of the band of the other three high-frequency channels that are not connected, the antenna connection circuit is short-circuited. As a result, the four high-frequency channels mean a short-circuit state, and any high-frequency channel causes an antenna mismatch state.
A conventional technique for avoiding this is to use a coupler in which a λ / 4 wavelength circuit is inserted between an antenna and a bandpass filter.
For example, when the impedance on the antenna side is viewed from the passband filter by inserting a coaxial line adjusted to a passband λ / 4 wavelength for each high frequency channel as a coupler between the antenna and the passband filter of each high frequency channel Since the frequency band other than the high-frequency channel is set to the out-of-band impedance ∞, impedance mismatch when a plurality of high-frequency channels are connected is avoided.
As a problem here, the λ / 4 line can be used only when the ratio band is several percent, and it is difficult to isolate the frequency bands. Further, in a circuit that switches the length of the coaxial line, the tracking performance of the operation speed is inferior, it is difficult to maintain the accuracy, and the circuit volume is increased.
Therefore, the coupler must be able to perform high-speed switching at a speed of several tens of nanoseconds so that frequency tuning can be applied to a spread spectrum signal, and can be realized with a small size.

  An object of the present invention is to provide a high-speed tuning antenna duplexer suitable for spread spectrum communication by frequency hopping, which can perform high-speed switching of the tuning frequency and can simultaneously share a high-frequency channel having a plurality of frequency bands with one antenna. Is to provide.

In order to achieve this object, a high-speed tuning antenna duplexer includes a plurality of transceivers sharing one antenna, and at least one of the plurality of transceivers transmits and receives a spread spectrum signal. Because
The antenna duplexer includes a plurality of couplers each composed of a two-terminal n-pair circuit in which n ≧ 1, and each one end of the plurality of couplers is commonly connected to the one antenna and each other end is Connected to each of the plurality of transceivers,
Each of the two-terminal n-pair circuits of the plurality of couplers includes a series resonance circuit of an inductor and a capacitor, and at least one of the inductor and the capacitor is switched by a diode switch to correspond to the plurality of spread spectrum signals. It is controlled to perform a selection operation that resonates at a desired resonance frequency,
The Q value of the series resonant circuit including the inductor and the capacitor is set smaller than the Q value of the bandpass filter in the transceiver connected to the coupler,
The diode switch provided in the two-terminal n-pair circuit is switched at high speed in conjunction with the frequency hopping timing of the spread spectrum signal, and corresponds to the resonance frequency closest to the hopping frequency. Any one of the series resonant circuits is selected, and the one antenna is configured such that any of the plurality of transceivers can be used individually or simultaneously with other transceivers.

By implementing the present invention, the following effects are obtained.
(1) Since a high-speed tuning antenna duplexer that can support a spread spectrum communication system using frequency hopping and can simultaneously share a high-frequency channel using a plurality of radio frequencies with one antenna is realized. It is economical in terms of price and system maintenance / maintenance costs.
(2) It can cope with a frequency division multiplex communication system or a frequency hopping communication system in which effective utilization of radio frequency resources can be expected.
(3) Since it corresponds to a high-speed frequency hopping operation, an antenna duplexer that is resistant to noise and interference on a wireless line is realized.
(4) When a variable filter as in Patent Document 1 is provided as a band-pass filter in a transceiver, the number of variable steps is, for example, 175, but on the other hand, band division per coupler in the present invention The number (number of series resonant circuits) is much smaller (eg 16).
As described above, it is clear that the present invention is extremely useful and exhibits special effects in the future where the effective utilization of radio frequency resources is expected.

  FIG. 1 is a system configuration diagram showing an embodiment of the present invention. Here, 1 is an antenna, 2 is a high-speed tuning antenna duplexer, 10, 20, 30, 40 are each couplers, 3 is a transceiver including a bandpass filter (BPF1), and 4 is a bandpass filter (BPF2). A transceiver 5 includes a bandpass filter (BPF3) and 6 includes a bandpass filter (BPF4).

The coupler (10) becomes one series resonance circuit between the capacitor (C1) common to (L11) and (L12) when the inductor (L11) or the inductor (L12) is switched and selected, that is, , (L11)-(C1) and (L12)-(C1) are two series resonant circuits configured as a two-terminal pair circuit (1a-1b), and in order to obtain a predetermined frequency tuning, either resonance A frequency is selected. Z _A and Z _B are impedance converters, and the inductor (L) and capacitor (C) can be easily manufactured by reducing the operating impedance of the series resonant circuit. The impedance converter is, for example, a broadband transmission line type transformer using a core material.
Similarly, in the coupler (20), the coupler (30), and the coupler (40), two series resonant circuits are each configured as a two-terminal pair circuit (Na-Nb). This is a circuit in which the resonance frequency is selected.
In this way, it is provided with four couplers (10, 20, 30, 40) each consisting of a two-terminal four-pair circuit, and one end (1a, 2a, 3a, 4a) of each coupler is commonly connected to the antenna 1, The other end (1b) is connected to the bandpass filter (BPF1), the other end (2b) is connected to the bandpass filter (BPF2), and the other end (3b) is further connected to the bandpass filter (BPF3). ) And the other end (4b) is connected to the band pass filter (BPF4), and the high frequency channel signals (CH1, CH2, CH3, CH4) are connected to the respective transceivers (3, 4, 5, 6). ) Connected as.

Next, in the coupler (10), the inductor (L11) is selected by turning on the diode switches (D11, D12) or the inductor (L12) by turning on the diode switches (D13, D14). Is selected, and the selected series resonance circuit is configured by the capacitor (C1).
Similarly, in the coupler (20), the coupler (30), and the coupler (40), each diode switch selects one of the series resonant circuits.

The Q value of the series resonant circuit including the inductor and the capacitor in each coupler is set to be smaller than the Q value of the band pass filter included in each transceiver connected to each coupler.
A series resonant circuit of an inductor and a capacitor is provided between the band pass filter and the antenna, and operates so as to be tuned and impedance matched to the system signal frequency passed through the entire pass band of the band pass filter.

  Therefore, a diode switch (D11 to D14) such as a pin diode that can turn on / off a high-frequency signal at high speed can switch a series resonance circuit of an inductor and a capacitor at high speed in conjunction with the frequency hopping timing of the spread spectrum signal. The resonance frequency closest to the hopping frequency to be frequency hopped in the bandwidth of the pass filter (BPF1) is selected.

One end (1a, 2a, 3a, 4a) of each of the couplers (10, 20, 30, 40) is commonly connected to the antenna 1, and each diode (D11, D13, D21, D23, D31, D33, D41, D43) are commonly connected to each anode, and a predetermined fixed bias voltage (VbiasA) is applied to the anode of the diode from this common connection point.
On the other hand, a predetermined fixed bias voltage (VbiasB) is applied to the anode of the diode at the connection point between the capacitor C1 and the anode of the diode (D12, D14).
Similarly, the connection point between the capacitor C2 and the anode of the diode (D22, D24), the connection point between the capacitor C3 and the anode of the diode (D32, D34), and the connection point of the capacitor C4 and the anode of the diode (D42, D44) A predetermined fixed bias voltage (VbiasB) is applied to the anode of each diode.
The predetermined fixed bias voltage (VbiasB) is DC cut from the subsequent circuits (BPF1 to BPF4) by the capacitors (C1, C2, C3, C4).

In the coupler 10, the cathode of the diode (D11) is connected to the cathode of the diode (D12) via the inductor (L11), and a control voltage (Vcont11) is given to this connection point. Vcont11) turns on the diodes (D11, D12) and switches on them to form a series resonant circuit of the inductor (L11) and the capacitor (C1), or the cathode of the diode (D13) passes through the inductor (L12). Is connected to the cathode of the diode (D14), and a control voltage (Vcont12) is applied to this connection point. The control voltage (Vcont12) gates on (switches on) the diodes (D13, D14) and turns on the inductor (L12). ) And a capacitor (C1) in series resonance circuit.
When the control voltages (Vcont11, Vcont12) do not give a predetermined control voltage, the switch state constituted by the diode switches (D11 to D14) is the OFF state, no series resonance circuit is formed, and the antenna And BPF1 are open and disconnected.
Similarly, in the coupler (20), the coupler (30), and the coupler (40), each pin diode can be turned on / off as a diode switch to form / not form a series resonance circuit.

In the above embodiment, two inductor and capacitor series resonant circuits to be switched are prepared per coupler, but a larger number of series resonant circuits can be prepared, and a selective operation with a predetermined control voltage can be performed. Needless to say.
The number of series resonant circuits required per coupler is determined by the balance between the load Q value of the series resonant circuit and the number of band divisions that are a plurality of high-frequency channels of the system shared by one antenna at the same time.
For example, for one high-frequency channel in a system using 225 MHz to 400 MHz (for example, high-frequency channel frequency 225 MHz, bandwidth 10 MHz), when the load Q value of the series resonance circuit of the inductor and the capacitor is 5, one The number of band divisions in the combiner can be up to 16. Therefore, the series resonance circuit of the inductor and the capacitor is determined to be 16.

  In addition, the number of couplers as antenna duplexers is determined by the relationship between the entire radio frequency bandwidth possessed as a system shared simultaneously using one antenna and the high frequency channel frequency bandwidth therein, so the necessary number Of course, it is not limited to the four couplers of this example, and it goes without saying that a large number of four or more can be achieved.

  Between the load Q value (Qfil) of the band-pass filter in the transceiver and the load Q (Qcom) of the series resonant circuit in the coupler, a magnitude relationship of “Qfil> Qcom” is secured, thereby ensuring the system. Have been adapted.

  The embodiment is a configuration of a series resonance circuit in which the inductor is switched by a pin diode and the capacitor is shared. Good.

The series resonant circuit of the coupler constituting the high-speed tuning antenna duplexer and the bandpass filter in the subsequent transmitter / receiver connected thereto operate in response to switching of the hopping frequency modulated by frequency hopping. In particular, the series resonance circuit of the coupler is impedance matched to the antenna and the band pass filter in the transceiver in the pass frequency band, so that the impedance is set to ∞ (circuit open state) outside the pass frequency band. .
Because of such characteristics, in the connection between the coupler and the band-pass filter (for example, four high-frequency channels) included in the transceiver, the coupler is connected from the input terminal of the first high-frequency channel band-pass filter (BPF1). The impedance viewed from the output terminal (1b) side of (10) passes a signal with no attenuation matched to a predetermined impedance in its own high frequency channel frequency band, but the fourth one from the other second high frequency channel. For the frequency band up to the high frequency channel, the impedance appears to be open and attenuates.
Therefore, the passband signal of the first high-frequency channel 1 (CH1) is not limited to the band signals of the other high-frequency channels (the example of FIG. 1) as long as the minimum detuning frequency is secured as the frequency interval between adjacent high-frequency channel bands. Then, it is not affected by CH2 to CH4).
For example, in a system in which a radio frequency band of 225 MHz to 400 MHz is divided into a plurality of high frequency channels and a plurality of high frequency channels are used at the same time, the detuning frequency is set to 15% of the ratio band (for example, ± 34 MHz with respect to 225 MHz), It has been confirmed by simulation that if the reflection at the detuning frequency (S parameter: S ₁₁ ) can be −10 dB or less, the return loss seen from the transceiver in all channels is −15 dB or less.
As shown in the frequency characteristic diagram example of FIG. 2, in the example of assignment of four high-frequency channels, CH1 = 225 MHz, CH2 = 260 MHz, CH3 = 300 MHz, and CH4 = 400 MHz. Solid characteristic curve Figure 2 shows the frequency characteristic of the high frequency channel (corresponding to S ₁₂ of S parameters), the broken line characteristic curve showing the frequency characteristics of the reflected wave (corresponding to S ₁₁ of S parameters).

  As shown in the example of FIG. 3, the coupler for matching the impedance of the base of the antenna and the input impedance of the band pass filter in the transceiver to a predetermined impedance is one of the L11-C1s in the coupler. The bandwidth (A) of the series resonance circuit characteristic and the bandwidth (B) of the other L12-C1 series resonance circuit characteristic are made larger than the bandwidth (W) of the BPF1 band-pass filter characteristic included in the transceiver. Thus, the spread spectrum signal (s1... Sk,... Sm... Sn) is efficiently passed without impairing the filter characteristics of the bandpass filters BPF1 to BPF4 required for each transceiver.

The number n of frequency switching steps of the band-pass filter is 175 as an example, and naturally, the number of frequency hopping is more than this (for example, the narrowest hopping interval is 25 kHz).
If the number of series resonance circuit circuits (number of band divisions) of the coupler is 16, 175 ÷ 16≈10, and the number of hoppings of 10 or more per one circuit of the series resonance circuit is accommodated. As described above, the series resonant circuit of the coupler is a high-speed tuned antenna duplexer that is switched following the hopping speed of frequency hopping and that corresponds to a spread spectrum signal by frequency hopping.

  Needless to say, a high-speed tuned antenna duplexer having a high-speed switching of the series resonance circuit is also used in a communication system other than the spread spectrum communication system using frequency hopping.

As shown in FIG. 4 as the second embodiment, the coupler (50) has, for example, a parallel circuit of an inductor (L51) and a capacitor (C51), and such unit parallel circuit has six circuits ( C51-L51, C52-L52,... C56-L56) are connected as a whole and configured as a two-terminal circuit of a series resonance circuit by Cc-Lc- (added value of selected L51 to L56).
In the unit parallel circuit, for example, when a control voltage (V51) is applied to the diode switch (D51), it is turned on, and a low-impedance capacitor (C51) is formed as a circuit to invalidate L51 having a predetermined inductance value. Otherwise, if the control voltage (V51) is not applied, it is turned OFF and the capacitor (C51) does not form a low impedance circuit, and performs a selection operation that makes L51 effective. The capacitor (C51) has a low impedance and a DC cut, prevents the control voltage (V51) from being short-circuited by the inductor (L51), and has a sufficiently small impedance for a high-frequency signal. Thus, C51 to C56 act as a bypass in each unit parallel circuit.
The six unit parallel circuits are independently turned ON / OFF by the control voltage (V51 to V56), so that the added value of L51 to L56 has 2 ⁶ = 64 combinations, and 64 tuning frequencies are obtained. A two-terminal circuit of a series resonance circuit is formed by Cc-Lc- (the added value of selected L51 to L56) that is switched at high speed.
FIG. 5 shows that for each level of 64 control voltage ON / OFF combinations, 64 set tuning frequencies can be obtained in the system frequency range of 225 MHz to 400 MHz.

Similarly, in the coupler (60), the coupler (70), and the coupler (80), each of the six series resonant circuits is configured as a two-terminal circuit, and each of the couplers is set in any of 64 ways. In this circuit, the tuning frequency is selected according to the resonance frequency.
Further, each of the six series resonant circuits included in the coupler (50) to the coupler (80) does not generate the same combination level of the same control voltage ON / OFF between the couplers (between multiple bands) at the same time. It is desirable to be controlled.
Therefore, a diode switch such as a pin diode that can turn on / off a high-frequency signal at high speed can switch a series resonance circuit of an inductor and a capacitor at high speed in conjunction with high-speed timing.

Table 1 shows a specification example of the high-speed tuning antenna duplexer in the second embodiment.

A constant design example of the high-speed tuning antenna duplexer in the second embodiment is shown in Formula 1.

As described above, an arbitrary series resonance circuit is selected in the coupler, and the same tuning frequency is not selected at the same time between any couplers. Therefore, the transmission / reception operation between the couplers may be any transmission / reception operation, Furthermore, the transceiver connected to the coupler may be in any transmission / reception switching operation.
That is, one antenna can be used by any of a plurality of transceivers individually or simultaneously with other transceivers.

  The present invention is applied to a mobile phone system using high-speed and high-frequency switching such as a spread spectrum communication system and a dedicated wireless communication system, and can be used for a communication business or the like.

It is a figure of the system configuration | structure of this invention, and a high-speed tuning antenna sharing device circuit. It is a frequency characteristic figure of the coupler circuit of this invention. It is a related conceptual diagram of the frequency characteristic of the radio frequency high frequency channel filter and coupler circuit of this invention. It is a figure of the coupler circuit of the 2nd Example of this invention. It is a figure of the coupler circuit of the 2nd Example of this invention. It is a circuit diagram of the frequency band variable filter of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Antenna duplexer 3-6 Transmitter / receiver 10, 20, 30, 40, 50, 60, 70, 80 Coupler 1a-4a, 1b-4b, 101, 102 Terminal BPF1-BPF4 Radio frequency high frequency channel filter C1- C4, C _C , C51 to C56, C101 to C106 Capacitors
CH1 to CH4 High frequency channel D11 to D14, D21 to D24, D31 to D34, D41 to D44, D51 to D56, D101, D102 Pin diode (switching diode)
_{L11, L12, L21, L22,} L31, L32, L41, L42, L C, L51~L56, L101~L105 inductor (coil)
VbiasA, VbiasB Bias voltage Vcont11, Vcont12, Vcont21, Vcont22, Vcont31, Vcont32, Vcont41, Vcont42, V51 to V56 Control voltage Z _A Impedance converter (for example, 50Ω → 12.5Ω)
Z _B impedance converter (eg 12.5Ω → 50Ω)
Z101, Z102 Distributed constant line

Claims (1)

A plurality of transceivers share one antenna, and at least one of the plurality of transceivers is an antenna duplexer for transmitting and receiving a spread spectrum signal,
The antenna duplexer includes a plurality of couplers each composed of a two-terminal n-pair circuit in which n ≧ 1, and each one end of the plurality of couplers is commonly connected to the one antenna and each other end is Connected to each of the plurality of transceivers,
Each of the two-terminal n-pair circuits of the plurality of couplers includes a series resonance circuit of an inductor and a capacitor, and at least one of the inductor and the capacitor is switched by a diode switch to correspond to the plurality of spread spectrum signals. It is controlled to perform a selection operation that resonates at a desired resonance frequency,
The Q value of the series resonant circuit including the inductor and the capacitor is set smaller than the Q value of the bandpass filter in the transceiver connected to the coupler,
The diode switch provided in the two-terminal n-pair circuit is switched at high speed in conjunction with the frequency hopping timing of the spread spectrum signal, and corresponds to the resonance frequency closest to the hopping frequency. Any one of the series resonant circuits is selected, and the one antenna is configured such that any of the plurality of transceivers can be used individually or simultaneously with other transceivers. High-speed tuning antenna duplexer.

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