JPH01300628A - Antenna common use circuit - Google Patents

Abstract

PURPOSE:To attain power saving by connecting diode group comprising plural diodes with the same polarity entirely in series with a DC circuit of two antenna common use circuits selectively respectively. CONSTITUTION:Diodes 66-71 selecting one of antenna common use filters 6, 7 are provided and a diode group 72 comprising three diodes (66, 68, 70) or over is conductive when the antenna common use filter 6 is selected and a diode group 73 comprising three diodes (67, 69, 71) or over is conductive when the antenna common use filter 7 is selected. The plural diodes 66-712 are connected with same polarity in series with the DC circuit entirely. Thus, in the case of selecting one of the two antenna common use filters 6, 7, flowing current is equal to a current by one diode. Thus, the power consumption is saved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an antenna sharing circuit for a wireless communication device that performs simultaneous transmission and reception, and particularly relates to an antenna sharing circuit configured to select and use two antenna sharing filters. .

[Conventional technology]

FIG. 3 shows a conventional antenna sharing circuit.

1 is a transmitting filter, and 2 is a receiving filter, each of which has a transmitting band and a receiving band as passbands. A transmitter is connected to terminal 3, a receiver is connected to terminal 4, and the antenna connected to terminal 5 is shared.

The frequency characteristics of the transmit filter 1 and the receive filter 2 at this time are shown by solid lines in FIG.

Here, as shown in FIG. 4, let us consider a case where the transmission band and the reception band are respectively expanded as BTXO''BTX31 BRXO''BRX3. When expanding the bandwidth in the same system 1 Normally, the transmission and reception interval is constant, so
The interval between the transmission and reception bands becomes narrow as a-+l).

On the other hand, assuming that the performance required of the system and wireless equipment remains the same even in the expanded band.

The passing loss of the transmitting filter and the amount of attenuation in the receiving band, the passing loss of the receiving filter and the amount of attenuation in the transmitting band are I
T, IR and LT t LR must be constant.

In such a case, the frequency characteristics required of the duplexer are as shown by the broken line in FIG. As is clear from the figure, the transmission filter and the reception filter require steeper attenuation characteristics, and as a result, a greater number of stages are required. Increasing the number of stages increases the passing loss within the band, so in order to reduce this it is necessary to increase the Q value of the resonant element, but this is accompanied by an increase in the volume of the resonant element in boat fishing.

In this way, when attempting to support a wider band with one antenna common filter as shown in FIG.

The volume of the antenna shared circuit increases for two reasons: firstly, the number of stages of resonant elements increases, and secondly, the volume of each resonant element increases. in this case.

The degree of volume increase depends on parameters such as the degree of band expansion, the transmission/reception interval, and the performance required of the system, but it may become an impediment in implementation in portable wireless devices and the like.

The method taken in such a case is shown in FIGS. 6 and 7. Both methods are as shown in FIG.

The expanded band is divided and assigned to two shared antenna filters, which are then selected and used by a switch. It is shown that when the band is divided in this way, it is possible to reduce the size of one antenna common filter rather than widening the band. Now assume that the bandwidth is doubled. Assume that the number of stages of the transmission filter and reception filter before expansion is five stages each, and the volume of each stage is a. Then.

What is the volume of the shared antenna filter before expansion?

5a+5a=10a.

Next, suppose that if a single antenna common filter is used to widen the band, the number of stages will need to be increased by three stages.

In this case, the transmit filter and the receive filter each have a configuration of eight stages. When increasing from 5 stages to 8 stages, approximately three times the Q value is required to maintain the same passing loss. Since Q is approximately proportional to the volume of the resonant element, the volume of the resonant element becomes Sa. In other words, when one antenna common filter is made to have a wide band.

8 X-a+8X-a=-a=25.6 a
−(1).

On the other hand, the total volume of the individual antenna common filters in the method of dividing the band into two is:

2x(5a+5a)=20a (2)
becomes. Comparing (1) and (2), it can be seen that the volume of 9 is 28% smaller in (2). In addition, when considering the fact that the more stages there are, the more difficult it becomes to adjust the filter as a practical problem, it is clear that the methods shown in FIGS. 6 and 7 are more advantageous than the method shown in FIG. 3. Now, FIG. 6 shows a method in which the antenna common filter is switched using a mechanical switch such as a high frequency relay, and FIG. 7 shows a method in which the antenna common filter is switched using an electronic switch such as a PIN diode.

However, either method has problems as described below.

[Problem to be solved by the invention]

In the case of the mechanical switch shown in Figure 6, 3
Switches 8, 9, and 10 are required.

If the volume is large, the advantage of miniaturization by dividing the band is lost. Also, the response speed of relays is relatively slow, which can cause system problems.

The direct current flowing through the three relays becomes a major hindrance in terms of power supply in the case of portable wireless devices that require power saving.

On the other hand, in the case of FIG. 7, since a diode is used, the increase in volume is relatively small and the response speed can be increased. However, it is necessary to constantly flow the sum of the forward currents of at least three diodes (diodes 11 to 13 and diodes 14 to 16).

Power consumption is still a design issue.

[Means to solve the problem]

In order to solve the problems of the prior art explained above.

The antenna sharing circuit of the present invention includes a first antenna sharing filter and a second antenna sharing filter.

One of the first and second antenna common filters is selected by a diode switching circuit to connect the transmitter and receiver to the antenna, and conducts when the first antenna common filter is selected. A plurality of diodes are connected in series with the same polarity in the DC circuit, and the plurality of diodes that conduct when the second antenna common filter is selected are also connected in series with the same polarity in the DC circuit. do.

〔Example〕

FIG. 1 shows one embodiment of the present invention, and the same parts as in FIG. 7 are given the same numbers. The diodes for selecting one of the antenna common filters 6 and 7 are 66-71, and the DC bias circuits for these diodes are RF choke coils 39-46 and 56-58. It is isolated from the RF circuit by RF bypass capacitors 47-50 and 59-61, and is connected to terminals 3, 4.5 via DC blocking capacitors 51-55.

The method of connecting the diodes 66 to 71 and the bias circuit according to the present invention are not necessarily uniquely determined as in this embodiment, and the bias circuit may also use a distributed constant circuit such as a strip line instead of an RF choke coil. .

FIG. 2 shows an example of a direct current connection relationship of switching diodes according to the present invention.

Here, the group of three or more diodes 72 (diodes 66, 68, 70 in FIG. 1) are diodes that are conductive when the antenna common filter 6 is selected.

Furthermore, a group of three or more diodes 73 (diodes 67, 69, 71 in FIG. 1) are diodes that become conductive when the antenna common filter 7 is selected.

The reason we chose three or more here is that when one diode's resistance to high frequencies is not large enough when it is in the off state, two diodes are used.
This is because it can be handled in the same way when using more than one in series.

In FIG. 2, the terminal 63 is always connected to a high potential via a resistor 74, and the terminal 65 is always connected to a low potential, here GND, via a resistor 62. In the example of FIG. 2, the diode group 73 is made conductive by setting the control terminal 64 to a potential of NO.

That is, the antenna common filter 7 is selected. Also, by setting the control terminal 64 to a low potential, the diode group 72
is conductive, that is, the antenna common filter 6 is selected.

Here, the resistors 62 and 74 are used for the purpose of controlling the current flowing through the diode.

〔Effect of the invention〕

As explained above, in the present invention, diode groups each consisting of a plurality of diodes are selectively connected to two antenna common circuits in series with direction and polarity using a DC circuit. As a result, the current that flows when one of the two antenna common filters is selected is equal to the current for one diode.

Power consumption can be significantly reduced. Further, by providing a control terminal for selecting two antenna common filters, an inverter or the like is not required, and selection can be easily made using only one control signal. Furthermore, since an electronic switch using a diode is used, the volume can be reduced and the response speed can be increased.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 shows an example of the connection of switching diodes according to the invention, Fig. 3 shows the configuration of a general transmitting/receiving filter, and Figs. FIG. 5 shows an antenna common circuit 6 according to a conventional example and the present invention.
The frequency characteristic diagram in FIG. 6 shows a conventional technique in which two common antenna filters are used and one is selected by a mechanical switch. FIG. 7 shows a conventional technique in which two common antenna filters are used and selected by a diode switch. In the figure, 6 and 7 are antenna common filters, 6T. 7T is a transmitting/receiving filter, and 6R and 7R are receiving filters. Fig. 3 Fig. 4 Fig. 5 He-→ To-← BTX3 BRX3 Fig. 6 Fig. 7

Claims (1)

[Claims] 1. It includes a first antenna common filter and a second antenna common filter, and one of the first and second antenna common filters is selected by a diode switching circuit to connect a transmitter and a receiver to the antenna. In the antenna common circuit configured to connect, all of the plurality of diodes that conduct when selecting the first antenna common filter are connected in series with the same polarity in the DC circuit, and the second antenna common filter is connected in series. An antenna common circuit characterized in that all of the plurality of diodes that conduct when being selected are also connected in series with the same polarity in a DC circuit.