JPH06244761A - Relay amplifier - Google Patents

Abstract

PURPOSE:To miniaturize and economize relay amplifiers distributed and arranged in automobile telephone and portable telephone systems, etc. CONSTITUTION:A down line amplifier circuit and an up line amplifier circuit connected between a base station side transmission/reception shared antenna connecting point 1 and a mobile station side transmission/reception shared antenna connecting point 2 are respectively constituted of input side filters 3 and 8 for suppressing the sneak path of opposite band signals, first amplifiers 4 and 9, intermediate filters 5 and 10 for making a noise figure small, second amplifiers 6 and 11 and output side filters 7 and 12 for which the attenuation of the opposite band signals is reduced. Thus, since the performance required for the filters are distributed to three filters, the standard of the respective filters is relaxed, a resonator with low non-load Q can be adopted and the amplifier is comprehensively miniaturized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless relay amplifying device which is distributed and arranged in, for example, a multistory parking lot, a tunnel, an underground shopping mall, etc. as a dead zone countermeasure for an automobile telephone system and a mobile telephone system.

[0002]

2. Description of the Related Art For example, in a car telephone system and a mobile telephone system, all communication between mobile stations and between a mobile station and a telephone of a public line is performed via a base station. The radio link frequencies of the base station and the mobile station are different from each other, and the downlink frequency band from the base station side to the mobile station (downband) and the uplink frequency band from the mobile station to the base station (uplink band) are predetermined. It is allocated at intervals. Such a base station,
A wireless relay amplifier installed in a dead zone where the radio waves between mobile stations do not reach, such as a tunnel or an underground parking lot, is equipped with a base station antenna and a mobile station antenna as transmitting and receiving antennas, respectively. It has a function of bidirectionally repeating and amplifying an upstream signal and suppresses intermodulation distortion due to simultaneous multi-frequency amplification.

FIG. 3 is a block diagram (A) of a main part of a conventional relay amplifier and a characteristic diagram (B) of the filter. In the figure, reference numerals 1 and 2 denote connection points with the shared antenna on the base station side and the shared antenna on the mobile station side, respectively. The downlink signal in the downlink band from the base station to the mobile station is selectively amplified by the downlink amplifier circuit, and the uplink signal in the uplink band from the mobile station to the base station is selectively amplified by the uplink amplifier circuit. The downlink amplification circuit is a downlink input side filter (Down-li
nk Input filter, hereinafter referred to as DI filter) 21,
Downlink signal amplifier (Down-link Amplifier: DA)
MP, hereinafter referred to as a downstream amplifier) 22, and a downlink output side filter (Down-link Output filter, hereinafter referred to as a DO filter) 23. The upstream amplification circuit includes an upstream input side filter (Up-link Input filter, hereinafter referred to as UI filter) 24, an upstream signal amplifier (Up-link Amplifier: U-AMP, hereinafter referred to as upstream amplifier) 25, an upstream output side. Filter (Up-li
nkOutput filter, hereinafter referred to as UO filter) 26. Down Amplifier 22 and Up Amplifier 2
Reference numeral 5 is a wide band amplifier with a small in-band deviation.

The characteristic D shown in FIG. 3B is the downlink D.
The filter characteristic of the I filter 21 and the DO filter 23 is shown, and the characteristic U shows the filter characteristic of the UI filter 24 and the UO filter 26 of the uplink. This filter characteristic D,
U is set so as to attenuate each other's pass band signals, and in particular, in the DO filter 23 and the UO filter 26 connected to the output side of the amplifier, the noise component of the other line band is shown by the broken line in the figure. As described above, the noise amount (NF) of the amplifier is deteriorated and the attenuation amount L ₀ is about 80.
It is set to dB or higher.

For example, the attenuation amount L ₀ for the DO filter 23 for suppressing the deterioration of the NF of the upstream amplifier 25 due to the noise sneaking into the upstream from the downstream DO filter 23 is calculated and set as follows. It The noise amount N _D in the downlink band generated in the downlink amplifier 22 is expressed by the following equation, where NF _{D is} the noise figure and G is the gain of the downlink amplifier 22. N _D = kTB · NF _D · G where k: Boltzmann's constant T: absolute temperature B: equivalent noise bandwidth In addition, the amount of noise N in the upstream band generated by the downstream amplifier 22.
_{The DU} is expressed by the following equation (1) when the attenuation amount of the upstream band of the DO filter 23 is L ₀ .

[0006]

[Equation 1] N _DU = kTB · NF _D · G / L ₀ (1) The input conversion noise amount in the upstream amplifier 25 is the sum of the noise generated by itself and the formula (1). , And the noise figure of the upstream amplifier 25 is NF _U , it is expressed by the following equation (2).

[0007]

(2) (kTB · NF _D · G / L ₀ ) + kTB · NF _U (2) Therefore, the noise figure NF of the uplink amplifier circuit is as follows (3)
It becomes an expression.

[0008]

[Equation 3]

Therefore, the noise figure NF _{U of the} upstream amplifier 25
Required attenuation amount L ₀ for suppressing deterioration of 0.5 dB or less
Ask for. For example, G = 70 dB, NF _U = 10 dB,
Let NF _D = 10 dB.

[0010]

[Equation 4] According to the conditions of the above equation, the values are arranged as follows and the values are as follows.

[0011]

[Equation 5] Therefore, the required attenuation amount L ₀ is about 80 dB.

Further, in the case of the above attenuation amount, if there is a gain in the loop shown by the one-dot chain line in FIG. Therefore, the margin for preventing unnecessary oscillation is set as follows. For example, as shown in FIG. 3A, assuming that the gains of the downstream amplifier 22 and the upstream amplifier 25 are 72 dB, and the in-band loss of the four upstream and downstream filters is 1 dB, the upstream amplifier circuit and the downstream amplifier circuit. The gain of each is 70 dB, and the attenuation of the input filter and the output filter is 8
Since it is 0 dB, the margin is -20 dB as in the following equation.
Becomes 70 dB + 70 dB-80 dB-80 dB =-
In order to further increase the margin by 20 dB, it is desirable that the amount of attenuation for the other band of the filter is 80 dB or more and the in-band loss is as small as possible.

[0013]

In the case of the conventional structure as described above, in consideration of a change in characteristics due to a change in ambient temperature and a secular change, the in-band loss is further small and the attenuation amount in the other band is large. A filter is needed. Therefore, there is a problem that the order of the filter becomes high, and the filter becomes large in size and expensive, which is a big limitation for downsizing the device. Therefore, if the filter is left as it is, there is a risk that third-order distortion is generated due to multi-frequency common amplification and intermodulation distortion is generated. If the supply power is increased to reduce the distortion generation amount, heat generation of the power source becomes a problem. There are restrictions such as.

It is an object of the present invention to provide a relay amplifying device which is downsized and economical while maintaining the performance required for the filter as described above.

[0015]

A relay amplifier of the present invention is a relay amplifier for bidirectionally relaying and amplifying a downlink signal from a base station to a mobile station and an uplink signal from a mobile station to a base station. Each of the downlink amplification circuit that selectively amplifies the downlink signal and the uplink amplification circuit that selectively amplifies the uplink signal connected between the transmission / reception shared antenna and the mobile station side transmission / reception shared antenna has two
One amplifier and three band pass filters, and the two amplifiers and the three band pass filters include an input side filter, a first amplifier, an intermediate filter, a second amplifier,
It is characterized in that the filters on the output side are connected in this order.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram (A) showing an embodiment of the present invention and a filter characteristic diagram (B). In the figure,
Reference numerals 1 and 2 are connection points with the antenna. The downlink amplification circuit has three BPFs (bandpass filters) 3.
5 and 7 and two amplifiers 4 and 6, and the upstream amplification circuit also includes three BPFs 8, 10, 12 and two amplifiers 9,
It is composed of 11.

Downlinks (Down-link) 3, 5 and 7 are input side filters (DI / F) and intermediate filters (DM /
F), an output side filter (DO / F), 4 is a preamplifier (DP / A: Down-link Pre-Amplifier), 6
Is the main amplifier (DM / A: Down-link Main Amplifie)
r). Similarly, 8, 1 of the uplink (Up-link)
Reference numerals 0 and 12 denote an input side filter (UI / F), an intermediate filter (UM / F), an output side filter (UO / F), and 9
Is a preamplifier (UP · A), 11 is a main amplifier (UM · A)
A).

As described above, the gist of the present invention is that the conventional amplifier is divided into the preamplifier and the main amplifier, and the intermediate filter is inserted therebetween, and the required performance for the conventional input side filter and output side filter is obtained. By sharing a part of the above with the intermediate filter, the overall size and cost are reduced.

The downlink will be described below. Since the intermediate filter 5 is provided in the middle of the two amplifiers, it has little influence on the noise figure and the output side distortion.
Like the characteristic DM · F shown by the broken line in (B), a loss in the pass band is allowed to some extent and the characteristics of the attenuation gradient are gentle, and an inexpensive dielectric filter can be used. Further, with such a configuration, noise to the uplink is reduced, so that the output side filter 7 may have a small attenuation gradient like the characteristic DO · F of FIG. 1 (B). Therefore,
Since the order of the output filters DO and F can be reduced, the in-band loss is reduced and the size is reduced. The input side filter 3 is a BPF having a steep characteristic DI · F with a large attenuation gradient even if the in-band loss increases a little because the main function is to suppress the oscillation due to the sneak of the upstream band signal. The above is a description of the downlink amplifier circuit, but the same applies to the uplink amplifier circuit if the uplink band is the pass band and the downlink band is the attenuation band.

Next, a noise figure (NF: Noise) indicating the degree of deterioration of the above-mentioned filter characteristics and signal-to-noise ratio (S / N).
Figure) will be described with specific numerical examples.
FIG. 2 is the same block diagram as the configuration example of the present invention in FIG. 1 (A).
The numerical examples of the noise figure (NF) are entered respectively. (1) First, the relative attenuation amount of the downstream intermediate filter 5 with respect to the upstream band is L _M dB (L _M = 40 dB in FIG. 1B).
Then, the NF of the uplink amplifier circuit is calculated. Up-band noise (out-of-band noise) N input to the down-link main amplifier 6
_{Since 1} is the output noise of the downlink preamplifier 4 attenuated by the intermediate filter 5, it is expressed by the following equation.

[0021]

[Equation 6] However, NFp is the noise figure of the preamplifier including the input filter 3 and the intermediate filter 5, Gp is the same gain, and L _M is the amount of attenuation in the upstream band of the intermediate filter 5 as described above.

The upstream band noise (out-of-band noise) N ₂ generated in the downstream main amplifier 6 is expressed by the following equation.

[0023]

[Equation 7] However, NF _M represents the noise figure of the main amplification section including the output filter 7, G _M represents the same gain, and L ₀ represents the attenuation amount of the output filter 7 in the upstream band. Therefore, the noise N ₃ upward band output from the downlink amplifier and the N ₁ main amplifier 6
Since it is obtained by adding the above N ₂ to the amplified one, it is expressed by the following equation.

[0024]

[Equation 8] Input noise N _{4 of} this noise N _{3 in} the upstream amplifier circuit
Is as follows.

[0025]

[Equation 9] Therefore, the noise figure NF of the desired uplink amplifier circuit is N
Since F = N ₄ / kTB, the following is obtained.

[0026]

[Equation 10]

(2) Next, L ₀ is calculated when the deterioration of NF _U of the upstream amplifier circuit is 0.5 dB or less. That is, the conditional expression is represented by the following expression.

[0028]

[Equation 11] NF ≦ NF _U · 10 ^{0.5 / 10} (5) Here, the insertion loss of each filter shown in FIG. 2 and shown in FIG. 1 (B) and the gain of the amplifier (Gp, G _M ), Noise figure (NF
Substituting the numerical values of p, NF _M ) into the equations (4) and (5) gives the following.

[0029]

[Equation 12]

From the above results, it is understood that the relative attenuation amount L ₀ of the downlink output side filter 7 with respect to the upstream band may be about 50 dB or more in consideration of temperature characteristics, secular change and the like.
Therefore, the characteristic of the output side filter 7 is as shown by the characteristic DO · F in FIG.

As described above, the characteristic D of the conventional output-side filter 23 shown in FIG. 3 and the output-side filter 7 having the configuration of the present invention shown in FIG. 1 when the deterioration of NF is 0.5 dB. Comparing the characteristics DO and F, it can be seen that the relative attenuation amount for the upstream band is 49.1 dB, which is 30.4 dB reduced in the present invention, whereas 79.1 dB was conventionally required. Therefore, the insertion loss becomes smaller because a filter with a smaller order than that of the conventional one is sufficient. When the loss is the same, a resonator having a small unloaded Q can be used, which greatly contributes to downsizing and economy. The same applies to the output filter on the uplink.

Next, regarding the input side filters 3 and 8, it is sufficient to suppress the oscillation due to the wraparound, and the attenuation amount of the input side filter is calculated by setting the margin for that, that is, the loop attenuation amount to 20 dB. Assuming that the upstream band attenuation of the downstream input side filter 3 is L _I (dB), from the characteristic DM · F, the characteristic DO · F of FIG. 1 (B) and the numerical example of FIG. L _I + 40-40-4 + 40
-50-1 = L _I -15 a (dB). On the other hand, since the amount of transmission on the uplink is 70 dB, the loop attenuation amount is 20
If dB is given, the following equation is obtained. −20 = L _I −15 + 70 ∴L _I = −75 dB Therefore, it is understood that the upstream band attenuation amount of the downstream line input side filter 3 may be 75 dB as shown in FIG. 1 (B). The same applies to the upstream input filter 8.

[0033]

As described in detail above, by implementing the present invention, the number of filters is greater than in the prior art, but the order of each can be reduced, so that the time for manufacturing and adjusting the filter is significantly shortened. . Moreover, since the no-load Q of the filter can be reduced, the size of the filter can be greatly reduced, which greatly contributes to downsizing of the entire apparatus and cost reduction, which is extremely effective in practice.

[Brief description of drawings]

FIG. 1 is a block diagram and a characteristic example diagram showing an embodiment of the present invention.

FIG. 2 is a specific numerical example diagram of FIG.

FIG. 3 is a block diagram and a characteristic example diagram of a conventional device.

[Explanation of symbols]

 1 Base station side connection point 2 Mobile station side connection point 3 Downlink input side filter 4 Downlink preamplifier 5 Downlink intermediate filter 6 Downlink main amplifier 7 Downlink output side filter 8 Uplink input side filter 9 Uplink front On-line amplifier 10 Uplink intermediate filter 11 Uplink main amplifier 12 Uplink output side filter 21 Downlink input side filter 22 Downlink amplifier 23 Downlink output side filter 24 Uplink input side filter 25 Uplink amplifier 26 Uplink output side filter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Sera 2-3-13 Toranomon, Minato-ku, Tokyo Kokusai Electric Co., Ltd.

Claims (1)

[Claims] 1. A relay amplification device for bidirectionally relaying and amplifying a downlink signal from a base station to a mobile station and an uplink signal from a mobile station to a base station, wherein a base station side transmission / reception shared antenna and a mobile station side transmission / reception shared antenna are provided. Each of a downlink amplification circuit for selectively amplifying the downlink signal and an uplink amplification circuit for selectively amplifying the uplink signal, which are connected in between, each include two amplifiers and three bandpass filters. And the three band-pass filters are an input side filter, a first amplifier, an intermediate filter, a second amplifier and an output side filter, which are connected in this order.