JPH0511572U - Signal switching circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the number of components, power consumption, and control signals for a signal switching circuit that switches and selectively outputs an input high-frequency signal. [Constitution] The cathode of the diode D ₁ is connected to the transistor Q.
Supply voltage V through a coil L ₁ is _one of the collector load
Connect to _CC1 to bias. Similarly, the anode of the diode D ₂ is also biased by being connected to the power supply voltage V _CC1 via the coil L ₁ . Binary control signal V _C1 to the anode of the diode D ₁ via a resistor R _1, are respectively connected via a resistor R ₂ to the cathode of the diode D _2, a diode D _1,
One of D ₂ turns on. Therefore, the input high frequency signal a is selectively output to one of the output terminals 3 and 4 according to the binary control signal V _C1 .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a signal switching circuit, and more particularly to a signal switching circuit that switches an input high frequency signal to selectively output it.

[0002]

[Prior Art]

FIG. 2 is a circuit diagram of a part of a tuning circuit to which an example of a conventional high-frequency signal switching circuit is applied. In the figure, reference numeral 10 denotes a conventional signal switching circuit, which outputs an intermediate frequency signal a, which is an input high frequency signal amplified by a transistor Q _1, to a binary control signal input to control signal input terminals 5 and 11. Output to either one of the output terminals 3 and 4.

The intermediate frequency signal a is, for example, a radio wave in the 12 GHz band from a satellite is received by an antenna, converted into a high frequency signal in the 950 to 1800 MHz band, amplified, and then the oscillation frequency is controlled by desired channel data. Mixed with local oscillator frequency 402. It is an intermediate frequency signal frequency-converted to 78 MHz.

In the case of a Japanese broadcasting satellite, the bandwidth of the intermediate frequency signal a is set to 27 MHz. However, in the case of private communication satellites, the bandwidth may vary depending on the satellite, as is well known. For example, in the case of "JC-SAT", the bandwidth is 27 MHz as in the case of the broadcasting satellite, but in the case of "Superbird", the bandwidth is 36 MHz.

Therefore, the output terminals 3 and 4 of the signal switching circuit 10 are respectively connected with the surface acoustic wave filters 6 and 7 having different pass band widths according to the band width of the intermediate frequency signal a of the communication satellite to be received. The band was limited to prevent noise. The circuit of FIG. 2 will be briefly described below.

An intermediate frequency signal a, which is an input high frequency signal, is input to the base of the transistor Q ₁ from the input terminal 2 via the capacitor C _5, and the intermediate frequency signal a is amplified and output to the collector. .. The collector of the transistor Q ₁ is connected to the power supply voltage V _{CC 2} (+ 12V) via the resistor R ₄ .

On the other hand, the diodes D ₁ and D ₅ have their commonly connected cathodes grounded via a resistor R _3, and the output intermediate frequency signal a of the transistor Q ₁ passes through a capacitor C ₆ to the diode D ₁ , It is supplied to the common connection point of D ₅ .

Diode D₁, D_FiveEach anode has a resistance R₁, R₂It is connected to the control signal input terminals 5 and 11 via. The control signal input terminals 5 and 11 are binary control signals V whose + 12V is a high level and 0V is a low level according to the communication satellite to be received. _C1 And V_C2Is supplied.

When V _C1 is at a high level and V _C2 is at a low level, the diode D ₁ is turned on and the diode D ₅ is turned off, so that the intermediate frequency signal a is output to the output terminal 3 via the capacitor C _1. To be done.

At this time, since V _C1 becomes high level, the diode D ₃ disposed between the output of the surface acoustic wave filter 6 and the output terminal 8 is turned on, and the output and output terminal of the surface acoustic wave filter 7 are turned on. The transistor Q ₄ provided between the transistor 8 and 8 is turned off. Therefore, the intermediate frequency signal a passes through the surface acoustic wave filter 6 and is band-limited, and is output to the output terminal 8 via the diode D ₃ .

When V _C2 is high level and V _C1 is low level, the diode D ₅ is turned on and the diode D ₁ is turned off, so that the intermediate frequency signal a is output to the output terminal 4 via the capacitor C _2. To be done. At this time, since V _C1 becomes low level, the diode D ₃ is turned off and the transistor Q ₄ operates to pass the surface acoustic wave filter 7 to amplify the band-limited intermediate frequency signal a and adjust the gain. Output to the output terminal 8.

The intermediate frequency signal a, which has been subjected to a predetermined band limitation and output to the output terminal 8, is FM-demodulated after being amplified, and a desired signal is taken out.

[0013]

[Problems to be solved by the device]

However, the conventional signal switching circuit requires the components of the resistors R ₁ R ₃ , R ₅ and the diodes D ₁ , D ₅ to switch the signal, and the power consumption by the resistor R ₃ cannot be ignored. Also, two types of control signals, V _C1 and V _C2 , were required.

In view of the above points, it is an object of the present invention to provide a signal switching circuit that can reduce the number of parts and power consumption and can switch signals with one type of control signal.

[0015]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention has a coil whose one end is connected to a power supply voltage, a transistor which amplifies an input high frequency signal and outputs it to a collector connected to the other end of the coil, and a binary control at one end. A first resistor to which a signal is input and the anode of the first diode is connected to the other end; and a second resistor to which a binary control signal is input at one end and the cathode of the second diode is connected to the other end. In order to selectively output the input high frequency signal to the other end of either the first or second resistor by turning on one of the first and second diodes by the binary control signal, The cathode of the ion and the anode of the second diode were biased by the power supply voltage through the coil.

[0016]

[Action]

 According to the present invention having the above structure, one of the first diode whose cathode is biased by the power supply voltage and the second diode whose anode is biased by the power supply voltage is turned on by the binary control signal, and the transistor is turned on. The input high frequency signal amplified by is operated to be selectively output to the other end of either the first or second resistor.

[0017]

【Example】

FIG. 1 is a circuit diagram of a part of a tuning circuit to which an embodiment of the present invention is applied. In the figure, the same components as those in FIG. 2 are designated by the same reference numerals. In the figure, 1 denotes a signal switching circuit of an embodiment of the present invention, the intermediate frequency signal a is input high frequency signal amplified by the transistor Q _1, is input to the control signal input terminal 5 2 Output to either output terminal 3 or 4 according to the value control signal.

Transistor Q₁In the base, capacitor C from input terminal 2_FiveThe intermediate frequency signal a, which is an input high frequency signal, is input via the amplifier, and the intermediate frequency signal a is amplified and output to the collector. Transistor Q₁Is a coil L₁Through the power supply voltage V _CC1 It is connected to (+ 5V). Transistor Q₁The collector load of is + 5V power supply voltage V_CC1The coil load is used to adjust the operating point.

On the other hand, the cathode of the diode D ₁ which is the first diode and the anode of the diode D ₂ which is the second diode are commonly connected and directly connected to the collector of the transistor Q ₁ .

The anode of the diode D ₁ is connected to the control signal input terminal 5 through the resistor R ₁ which is the first resistance, and the cathode of the diode D ₂ is connected to the control signal input terminal 5 through the resistor R ₂ which is the second resistance. It is connected to the. The control signal input terminal 5 is supplied with a binary control signal V _C1 whose state changes according to the bandwidth of the communication satellite to be received. The binary control signal V _C1 has a high level of + 12V and a low level of 0V.

Therefore, when the binary control signal V _C1 becomes high level (+12 V), the diode D ₁ has its anode connected to V _C1 of +12 V through the resistor R ₁ and its cathode through the coil L _1. It is turned on because it is connected to the power supply voltage V _{CC1 of} +5 V and is forward biased.

On the other hand, at this time, the diode D ₂ has its cathode connected to + 12V V _C1 via the resistor R ₂ and its anode connected to + 5V power supply voltage V _CC1 via the coil L ₁ and is therefore reverse biased. Turn off. Therefore, the intermediate frequency signal a amplified by the transistor Q ₁ is output to the output terminal 3 via the diode D ₁ and the capacitor C ₁ and supplied to the surface acoustic wave filter 6.

At this time, since V _C1 is at the high level, the diode D ₃ is turned on and the transistor Q ₄ is turned off. Therefore, the intermediate frequency signal a is passed through the surface acoustic wave filter 6 and subjected to a predetermined band limitation, and then output to the output terminal 8 via the diode D ₃ .

When the binary control signal V _C1 becomes low level (0 V), the diode D ₁ has its anode grounded via the resistor R ₁ and its cathode powered via the coil L ₁ at a power supply voltage V of +5 V. It is turned off because it is connected to _CC1 and is reverse biased.

Further, the diode D ₂ is turned on because the cathode is grounded via the resistor R ₂ and the anode is connected to the power supply voltage V _{CC1 of} +5 V via the coil L ₁ and forward biased. Therefore, the intermediate frequency signal a amplified by the transistor Q ₁ is output to the output terminal 4 via the diode D ₂ and the capacitor C ₂ and supplied to the surface acoustic wave filter 7.

On the other hand, when V _C1 is at the low level, the diode D ₃ is turned off and the transistor Q ₄ operates to pass the surface acoustic wave filter 7 to increase the band-limited intermediate frequency signal a. The gain is adjusted and output to the output terminal 8.

As described above, according to the above embodiment, the intermediate frequency signal a, which is the input high frequency signal, is amplified by the circuit having a smaller number of parts than the conventional signal switching circuit, and the pass band width is increased by the binary control signal. It is possible to output to one of the two types of surface acoustic wave filters of different types, perform band limitation according to the bandwidth, adjust the gain, and output to the output terminal.

[0028]

[Effect of the device]

 As described above, according to the present invention, it is possible to select and output the input high-frequency signal by using one type of binary control signal with a circuit having a smaller number of components than before, and reduce the resistance. Therefore, there is a feature that the power consumption can be reduced compared to the conventional circuit.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a part of a tuning circuit to which an embodiment of the present invention is applied.

FIG. 2 is a circuit diagram of a part of a tuning circuit to which an example of a conventional high-frequency signal switching circuit is applied.

[Explanation of symbols]

1, 10 Signal switching circuit Q ₁ transistor L ₁ coil R ₁ resistance (first resistance) R ₂ resistance (second resistance) D ₁ diode (first diode) D ₂ diode (second diode) V _C1 Binary control signal V _CC1 power supply voltage

Claims (1)

Claims for utility model registration 1. A coil having one end connected to a power supply voltage, a transistor for amplifying an input high frequency signal and outputting the amplified high frequency signal to a collector connected to the other end of the coil, 2 at one end A first resistor to which a value control signal is input and the anode of a first diode is connected to the other end; and a second resistor to which the binary control signal is input to one end and the cathode of a second diode is connected to the other end. And one of the first and second diodes is turned on by the binary control signal to selectively output the input high frequency signal to the other end of the first or second resistor. To do
A signal switching circuit in which the cathode of the first diode and the anode of the second diode are biased by the power supply voltage via the coil.