JPS6143888B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an amplifier circuit that can pass signals with low loss even when power is cut off.

Low-consumption wireless devices are used that reduce the power consumption of the wireless device by lowering its transmission output under certain conditions.

There are various possible specific conditions for such low consumption wireless devices. For example: (1) When it is determined that there is sufficient fading margin based on fading information from the opposite station, and the transmission power is reduced within that range.

(2) When attempting to reduce the transmission power of the backup route to the extent that the line status can be monitored in a backup route using a route backup method that preserves the backup route in hot standby mode.

(3) In a battery-powered wireless device, when it is desired to reduce the transmission power even if the S/N ratio is made to some extent due to a drop in battery voltage.

etc. are possible.

In such a case, transmission power is lowered in order to reduce power consumption, but interruption of transmission must be avoided. As a means for such a case, a switching system as shown in FIG. 1 has been conventionally used.

In FIG. 1, a radio frequency (RF) signal input from an input terminal 1 is normally input to a pass-through amplifier 3 via a switch 2, where it is amplified as required and output.
It is output from the output terminal 5 via the switch 4.
Now, when attempting to lower the transmission output as described above, the switchers 2 and 4 are respectively switched to the line 6 side. As a result, the signal from input terminal 1 is output to output terminal 5 without being amplified, and the transmission power is reduced. At this time, the power supply power that had been supplied to the amplifier 3 from the power supply terminal 7 is no longer supplied to the amplifier 3 because the power supply switch 8 is opened in synchronization with the switching of the switches 2 and 4 to the line 6 side. Thus, the purpose of reducing power consumption can be achieved.

This method of reducing transmission power using a switch requires the signal path switch to be able to pass the RF signal with low loss, which results in a complicated structure and an increase in price. , not necessarily desirable.

Furthermore, in order to easily perform such switching of RF signals, an amplifier circuit as shown in FIG. 2 can be considered. In FIG. 2, during normal operation, the RF signal input from the input terminal 11 is applied to the port _13-1 of the circulator 12, transferred inside the circulator in the direction of the arrow, and then sent to the port _13-2.
output from the pass-through amplifier 15 via line 14.
Enter. During normal operation, power switch 1
6 is closed, and the required power is applied to the pass-through amplifier 15 from the power supply terminal 17.

The pass-through amplifier 15 has an input impedance of the line 14 when the power is applied.
The output impedances are matched to the lines 18, respectively, and perform amplification with a constant amplification degree. Therefore, the RF signal applied to the pass-through amplifier 15 is amplified as required and outputted, inputted to the port _20-1 of the circulator 19 via the line 18, and transferred in the direction of the arrow within the circulator to the port 20-1.
- Output from ₂ and appear on terminal 21.

On the other hand, the switch 16 opens and the pass-through amplifier 15
When no power is applied to lines 14 and 18, the input and output impedances of pass-through amplifier 15 are significantly different from the impedances of lines 14 and 18, respectively. Therefore, the RF signal applied to the input of the pass-through amplifier 15 via the line 14 is reflected due to impedance mismatching and is sent via the line 14 again to the port 13 of the circulator 12.
₂ , is transferred through the circulator, is output from port _13-3 , and is added to isolator 22. The isolator 22 allows the input signal to pass through with low loss, and the output is input to the port _20-3 of the circulator 19, transferred through the circulator, output from the port _20-1 , and then sent to the output side of the pass-through amplifier 15 via the line 18. Added. On the output side of the pass-through amplifier 15, the signal is reflected due to impedance mismatching, passes through the line 18 again, enters the port _20-1 of the circulator 19, and is transferred within the circulator to the port 20-1.
₂ and appears at the output terminal 21.

In this way, when power is applied to the pass-through amplifier 15, the signal from the input terminal 11 is amplified as required and outputted to the output terminal 21, and when no power is applied, the signal from the input terminal 11 is amplified as required and outputted to the output terminal 21. The signal can be passed to the output terminal 21 with low loss without being amplified. At this time, the power to the pass-through amplifier 15 is cut off, so power consumption is reduced.

Note that, for example, the isolator 22 in FIG.
There is impedance mismatching between the load (not shown) connected to the circulator 19 and a part of the output power is passed from the port 20-3 of the circulator ₁₉ to the port _13-3 of the circulator 12 to the pass-through amplifier 15. This is to prevent unstable operation such as feedback to the input side and an oscillation state.

Generally, the input/output impedance of an amplifier changes when the power is turned off, resulting in a mismatch with the line impedance, but this may not always be sufficient. An object of the present invention is to provide an amplifier circuit that can ensure mismatching of input and output impedances of such an amplifier and can switch RF signals more efficiently. A detailed explanation will be given below based on examples.

Figures 3 and 4 show an example of a configuration in which the amplifier circuit shown in Figure 2 is provided with a circuit that actively changes the input/output impedance of the pass-through amplifier by connecting or disconnecting the power supply. be. In the figure, parts indicated by the same drawing numbers as in FIG. 2 represent the same components. In Figure 3,
The pass-through amplifier 15 has PIN diodes 32 and 33 connected to its input and output terminals, respectively, and when the amplifier 15 is in the operating state by connecting the switch 34, the switch 35, 36 is disconnected, the resistance values of the PIN diodes 32 and 33 are sufficiently high, and the amplifier 15 matches the lines 14 and 18, respectively, with the disconnected PIN diodes 32 and 33 connected to its input and output terminals. are doing.

On the other hand, when the switch 34 is open and the amplifier 15 is in an inactive state, the interlocking switch 3
5 and 36 are connected to PIN diodes 32 and 33
As the required current flows through the line, its low resistance value decreases significantly, so that the input and output terminal impedance of the pass-through amplifier 15 becomes mismatched with respect to the lines 14 and 18.

Further, in FIG. 4, the pass-through amplifier 15 has varactor diodes 37 and 38 connected to its input and output terminals, and when the power supply switch 16 is connected, the amplifier 15 is in an operating state, and the varactor diode 3
A reverse bias is applied to lines 7 and 38 so that their capacitance values are small, and the input and output terminal impedances of amplifier 15 are matched to lines 14 and 18.

On the other hand, when the switch 16 is opened and the amplifier 15 becomes inactive, the barrack diodes 37, 3
8 also loses its reverse bias, its capacitance value becomes significantly large, and the impedance at the input and output terminals of the pass-through amplifier 15 becomes mismatched with respect to the lines 14 and 18.

As explained above, according to the amplifier circuit of the present invention, without using a changeover switch in the signal path, it operates normally and performs amplification when power is applied, and does not perform amplification when power is turned off, but the input signal can be passed through with low loss, which provides convenience in terms of the configuration of the amplifier device.

In addition, in the amplifier circuit of the present invention, since a circuit is provided at the input/output terminal of the pass-through amplifier to make its impedance mismatched with the line only when the power is cut off, the input/output terminal impedance of the amplifier is ensured by cutting off the power. It is possible to switch the RF signal by making it mismatched. Therefore, no feedback is applied to the signal transmission system passing through the isolator, which is effective in improving the characteristics of the circuit.

The amplifier circuit of the present invention is suitable for use in a low-consumption wireless device that reduces the power consumption of the wireless device by lowering the transmission output under specific conditions. It is possible to apply it when it is necessary to do so.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional switching system, FIG. 2 is a block diagram showing the configuration of an amplifier circuit, and FIGS. 3 and 4 are block diagrams each showing a configuration example of a pass-through amplifier in the amplifier circuit of the present invention. It is a diagram. 1... Input terminal, 2, 4... Switch, 3... Pass-through amplifier, 5... Output terminal, 6... Line, 7
...Power terminal, 8...Power switch, 11...Input terminal, 12...Circulator, 13- ₁ , 13
― ₂ , 13 - ₃ ... Port of circulator 12, 14, 18 ... Line, 15 ... Pass-through amplifier, 16 ... Power supply switch, 17 ... Power supply terminal, 1
9... Circulator, 20- ₁ , 20- ₂ , 2
0- ₃ ...Circulator 19 port, 21...
...Output terminal, 22...Isolator, 32, 33
... PIN diode, 34, 35, 36 ... switch, 37, 38 ... varactor diode.

Claims (1)

[Claims] 1 Connect the input terminal and the first port of the first three-port circulator, and connect the second port in the signal transmission direction from the first port of the first circulator to the input end of the pass-through amplifier. a second port in the signal transmission direction from the first port of the second circulator; is connected to the output terminal, and further from a third port in the signal transmission direction from the second port of the first circulator to a third port in the signal transmission direction from the second port of the second circulator via an isolator. A switch is connected to the port of the pass-through amplifier and cuts off the power supply to the pass-through amplifier under external control, and an input/output terminal of the pass-through amplifier is connected to the input/output terminal impedance according to the control of the power cut-off switch. An amplifier circuit characterized by having a circuit that is mismatched with a connected line.