JPH0685641A - Microwave switch - Google Patents

Abstract

(57) [Abstract] [Purpose] The control of the MMIC SPDT switch is simplified. [Structure] A symmetric control voltage generating circuit 19 including a differential amplifier circuit is built in before the control terminals 4 and 5 of the SPDT switch. [Effect] It becomes possible to control the SPDT switch with a single power source, and it is possible to simplify the control circuit of the switch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave switch, and more particularly to MMIC (Microwave Monolithic Integrated).
Circuit) SPDT (Single Pole, Double Thro
w) Concerning the switch configuration method.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a conventional SPDT switch.
Shown in. The SPDT switch is a high-frequency switch for switching the input to a single input terminal to either of the output terminals of two signal lines and outputting it. In FIG.
1 is a single input terminal, 2 is an output terminal of a first system path, 3 is an output terminal of a second system path, 6 is a first signal line ON, O
FF is the first system path switch FET, 7 is the first system ground FET that grounds the output of the first system path, 8 is the second system path switch FET that turns on and off the second signal system path, and 9 is Second
A second system grounded FET 4 for grounding the output of the system path, 4 is a first control terminal connected to the gate of the first FET 6,
Reference numeral 10 is a gate resistance, 5 is a second control terminal connected to the gate of the second FET 8, and 11 is a ground.

Next, the operation will be described. A normally-on type FET is often used as the FET used in the MMIC. In the normally-on type FET, when 0V is applied to the gate terminal, conduction is established between the drain terminal and the source terminal, and F
ET is turned on. Pinch-off voltage V to the gate terminal
When p (for example, -5 V) is applied, the drain terminal and the source terminal become non-conductive, and the FET is turned off.

In the circuit of FIG. 4, 0 V is applied to the control terminal 4.
When Vp is applied to the control terminal 5, the first path switch FET 6 and the second path ground FET 9 are turned on,
Since the second system road switch FET8 and the first system ground FET 7 are turned off, the input terminal 1 and the first output terminal 2
Is conducted, the input terminal 1 and the second output terminal 3 are non-conducted, and the input signal is output to the first output terminal 2.

Next, when Vp is applied to the control terminal 4 and 0 V is applied to the control terminal 5, the first system path switch FET 6 and the second
The system grounded FET 9 is turned off, and the first system grounded F
Since the ET7 and the second system switch FET8 are turned on, conduction is established between the input terminal 1 and the second output terminal 3,
There is non-conduction between the input terminal 1 and the first output terminal 2,
The output signal is output to the second output terminal 3.

As described above, the first control terminal 4 and the second control terminal 4
By applying 0V and Vp symmetrically to the control terminal 5 of, the high frequency signal input to the input terminal 1 is
It is possible to output by switching to either the first output terminal 2 or the second output terminal 3.

[0007]

Since the conventional SPDT switch is constructed as described above, it is possible to obtain mutually symmetrical voltages in order to drive the switch.
The system control voltage was needed.

The present invention has been made to solve the above-mentioned problems, and does not require symmetrical control signals of two systems, and can be driven by a control voltage of one system. Aim to get.

[0009]

SOLUTION TO THE PROBLEMS The SPDT according to the present invention
The switch has a symmetrical control signal generating circuit such as a differential amplifier circuit that generates a pair of forward and reverse control signals from an input control signal in front of the pair of control terminals.

[0010]

In the present invention, in the SPDT switch,
Paying attention to the fact that symmetrical voltages are applied to the control terminal 4 and the control terminal 5, the symmetrical control signal generating circuit generates two symmetrical voltages from a single control voltage input,
Since it is applied to the first control terminal 4 and the second control terminal 5 of the switch, it is possible to drive the SPDT switch with a single control voltage.

[0011]

EXAMPLES Example 1. FIG. 1 shows S according to an embodiment of the present invention.
3 shows a PDT switch. In FIG. 1, 1 to 11 are the same as those in the conventional example. 13 and 14 are differential amplifier circuits 1
A pair of FETs forming the 9, and 12 are the FETs 13 and 14
Drain resistance, 15 are drain voltage terminals of both FETs 13 and 14, 16 and 17 are gate voltage terminals of differential configuration connected to the gates of both FETs 13 and 14, 18 is ground, and 19 is a differential amplifier circuit. Is a symmetrical control voltage generating circuit.

Next, the operation will be described. In the above differential amplifier circuit 19, when Vcc is applied to the drain voltage terminal 15, V1 is applied to the gate voltage terminal 16, and V2 is applied to the gate voltage terminal 17, the voltages generated at the terminals 4 and 5 are V3 and V4, respectively. The relationship between the voltages at the terminals is shown in FIG.

As shown in FIG. 2, the differential amplifier circuit has an F
The difference in gate voltage between ET13 and FET14 (V1-V2
) Changes the voltage at terminals 4 and 5.
Now, V4 = Vcc and V3 = 0V (V1-V2) +
Voltages at which V5, V4 = 0V, V3 = Vcc (V1-V2
) Is -V5. When the potential difference between the terminals 16 and 17 is set to + V5, Vcc is generated at the terminal 4 and 0V is generated at the terminal 5. On the contrary, the potential difference between the terminals 16 and 17 is −
When set to V5, 0V is generated at terminal 4 and Vcc is generated at terminal 5.

Therefore, Vcc applied to the terminal 15 is changed to FET
Set to pinch-off voltage Vp of 6, 7, 8 and 9 and
7 is fixed to + V5, terminal 16 is 0V and 2x (+ V5)
Therefore, 0 V or Vp is generated at the terminals 4 and 5 depending on the state of the terminal 16. That is, by controlling one voltage applied to the terminal 16, two kinds of voltages required to drive the SPDT can be obtained.

Therefore, the SPDT is built in by incorporating the differential amplifier circuit 19 which sets the voltage of each terminal as described above and generates a symmetrical control signal at the output terminals 4 and 5 by controlling one voltage.
By configuring the switch with the MMIC, it is possible to realize an SPDT switch that can be controlled by a single power source. At this time, set the control terminal of this SPDT switch to 1
Since the number can be reduced, the structure of the control circuit for generating the control voltage can be simplified.

Example 2. FIG. 3 shows an SPDT switch according to a second embodiment of the present invention. Reference numeral 20 is an inverter circuit, 21 is a control voltage input terminal, and 22 is a symmetrical control voltage generating circuit for generating a symmetrical control signal to the terminals 4 and 5 from a signal to the terminal 21. If the inverter circuit 20 is built in before the terminals 4 and 5 as in this embodiment, 0 V is applied to the terminal 21.
Is applied, 0 V is applied to the terminal 4 and Vp is applied to the terminal 5. Conversely, when Vp is applied to the terminal 21, Vp is applied to the terminal 4 and 0 V is applied to the terminal 5. Therefore, it is possible to obtain the two voltages required to control the SPDT switch with a single power source, and to control the SPD with a single power source.
A T-switch is realized. Also, the configuration of the circuit that generates the control voltage can be greatly simplified.

[0017]

As described above, according to the present invention, the MM
In the IC-based SPDT switch, a circuit for inputting a symmetrical control voltage such as a differential amplifier circuit is built in a circuit for inputting a control signal, so that a switching operation can be performed with a single control voltage input. is there. Also, SPD
There is also an advantage that the structure of the control circuit for generating the control voltage of the T switch can be simplified.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an SPDT switch according to an embodiment of the present invention.

FIG. 2 is a diagram showing an operation of a symmetrical control voltage generating circuit using a differential amplifier circuit.

FIG. 3 is a diagram showing an SPDT switch according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a conventional SPDT switch.

[Explanation of symbols]

 1 Input Terminal 2 Output Terminal 3 Output Terminal 4 Control Terminal 5 Control Terminal 6 1st System Road Switch FET 7 1st System Road Ground FET 8 2nd System Road Switch FET 9 2nd System Road Ground FET 10 Gate Resistance 11 Grounding 12 Drain Resistance 13 FET 14 FET 15 Drain voltage terminal 16 Gate voltage terminal 17 Gate voltage terminal 18 Ground 19 Symmetrical control voltage generation circuit by differential amplifier circuit 20 Inverter circuit 21 Control voltage input terminal 22 Symmetrical control voltage generation circuit

Claims (3)

[Claims] 1. A monolithic microwave integrated circuit (MM)
SPDT (Single Pole, Doubl)
In the e Throw switch, the control signal input section of the SPDT switch has a built-in symmetric control voltage generation circuit for generating a symmetric control voltage composed of a normal output and an inverted output with respect to the control signal input. Microwave switch to do. 2. The microwave switch according to claim 1, wherein the symmetrical control voltage generating circuit comprises a differential amplifier circuit. 3. The microwave switch according to claim 1, wherein the symmetrical control voltage generating circuit has an inverter circuit.