JPH09261111A - Rf switch and rf signal selector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the isolation by connecting an RF signal that passes through an RF signal line in the OFF state to ground. SOLUTION: A PIN diode D2, an input circuit for a bias signal S2 to control its ON/OFF state, and a short-circuit circuit consisting of a coil and a capacitor isolating the bias signal S2 from as RS signal are provided to an output side of a PIN diode D1 of an RF switch. When an RF signal line is set to the ON state, a forward current is supplied to a bias signal terminal S1 to turn/on the PIN diode D1 and a reverse voltage is applied to a bias signal terminal S2 to turn off the PIN diode D2. Furthermore, when the RF signal line is turn to the OFF state, a reverse voltage is applied to the bias signal S1 to turn/on the PIN diode D1 and a forward current is supplied to the bias signal S2 to urn on the PIN diode D2 so as to connect the RF signal passing through the PIN diode D1 to ground GND.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RF switch and an RF signal selector used in a frequency variable filter used in a transceiver of frequency hopping communication.

[0002]

2. Description of the Related Art An example of a conventional RF switch circuit is shown in FIG. In the figure, an RF switch includes a PIN diode D1, an input circuit of a bias signal S1 for controlling ON / OFF thereof, capacitors CIN, COUT and a coil L1, for insulating an input RF signal from the bias signal S1.
And L2.

The operation of this circuit is P by applying a forward current (DC current) bias signal S1 from the input circuit.
The IN diode D1 becomes conductive (hereinafter, turned on), and the RF signal line from the input to the output is turned on. Also, by applying a reverse voltage (negative voltage) from the input circuit, PI
The N diode D1 is insulated (hereinafter, turned off), and the RF signal line from the input to the output is turned off.

FIG. 6 shows an RF signal selector constructed by combining these RF switch circuits. The figure shows an RF signal selector circuit in which two RF switch circuits are combined. In the circuit diagram, when P1 → P2 is turned on and P1 → P3 is turned off, a forward current is applied to the bias signal S11 to operate the PIN diode. Turn on D11 and turn on P1 → P2. A reverse voltage is applied to the bias signal S21 to turn off the PIN diode D21 and turn off P1 → P3.

By the way, since the PIN diode is not an ideal switch, some RF signals pass even when it is in the OFF state. The ratio of the passing signals is isolation. In FIG. 6, P1 → P2 is turned on, P1 → P2
When 3 is turned off, P1 → P2 is insertion loss, P3 → P
1 is the isolation.

FIG. 7 shows an example of a circuit to which actual design values are applied, and FIG. 8 shows characteristics when P1 → P2 is turned on and P1 → P3 is turned off. Note that in FIG. 7 of the embodiment, the on-current is 100 mA and the off-voltage is -100 V.
Is the simulation result when the equivalent circuit is shown in FIG.

According to the characteristic diagram of FIG. 8, frequencies 100 to 5
At 00 MHz, the isolation of P3 → P1 is -40 to -20V.

[0008]

As described above, according to the conventional circuit configuration, even if the PIN diode is in the off state, the R
There is a drawback that the F signal passes and the isolation is not high.

An object of the present invention is to improve isolation by dropping the RF signal passing through when the RF switch of the RF signal line is turned off to the ground.

[0010]

SUMMARY OF THE INVENTION The above object is to provide an RF switch with a PIN diode D1 of the RF switch.
On the output side of the other PIN diode D2, and a bias signal S2 for controlling ON / OFF of the PIN diode D2.
R that passes through the input circuit and the PIN diode D2
The bias signal S2 is composed of a capacitor and a coil for insulating the F signal from the bias signal S2.
RF that is reversibly added to the bias signal S1 of the N diode D1 and passes through when the PIN diode D1 is turned off.
This is accomplished by an RF switch with a short circuit that pulls the signal through PIN diode D2 to ground GND.

Further, for the above-mentioned purpose, at least two of the above-mentioned RF switch circuits are combined and provided on an RF signal line, and each RF
RF is controlled by controlling the bias signals S1 and S2 of the switch.
This is achieved by an RF signal selector that selects a signal line.

Using the above means, when the RF signal line provided with the RF switch is turned on, the bias signal S
When a forward voltage is applied to the bias signal S2 and a reverse voltage is applied to the bias signal S2 so that the input RF signal passes through the PIN diode D1 and the RF signal line is turned off, a forward current is applied to the bias signal S2. A reverse voltage is applied to the bias signal S1, and the input RF signal is changed to the PIN diode D1.
The RF signal is blocked by the PIN diode D
Go through 2 to the ground GND.

Each R provided with the above RF switch circuit
The F signal line is used for bias signals S1 and S of each RF switch.
By the control of 2, the RF signal line through which the RF signal passes can be selected.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 1 shows an RF switch according to an embodiment of the present invention.
On the output side of the N diode D1, another PIN diode D
And a short circuit composed of a bias signal S2 input circuit for controlling ON / OFF of the PIN diode D2, a capacitor C1 for insulating the RF signal from the bias signal S2, and a coil L3.

In this embodiment, the forward current (DC current) is applied to the bias signal S2, so that the PIN diode D
2 is turned on, and part of the RF signal is ground GND
Is dropped. Further, by applying a reverse voltage (minus voltage) to the bias signal S2, the PIN diode D2 is turned off, and the RF signal is controlled so as not to drop to the ground GND.

Therefore, when the RF signal line from the input to the output provided with the RF switch is turned on, a forward current is applied to the bias signal S1 to turn on the PIN diode D1 and a reverse voltage is applied to the bias signal S2. By turning off the PIN diode D2 by acting on, the input RF signal is output as it is through the PIN diode D1.

When turning off the RF signal line,
Applying reverse voltage to bias signal S1 and PIN diode D
If 1 is turned off and a forward current is applied to the bias signal S2, P
The IN diode D2 is turned on, and part of the RF signal passing through the PIN diode D1 in the off state is turned on.
It can be dropped to the ground GND through the diode D2, and the RF signal passing through the RF signal line in the off state can be reduced. In this way, the bias signals S1 and S
The RF signal line can be reliably turned on and off by reversibly controlling 2.

FIG. 2 shows an R using the RF switch of the present invention.
It is an embodiment of an F signal selector. The two RF switch circuits of FIG. 1 are combined and provided on the RF signal line to select the RF signal of the input P1 to the output P2 or P3.

In this selector circuit, when P1 → P2 is turned on and P1 → P3 is turned off, the bias signal S1
1 by applying a forward current to turn on the PIN diode D11 and applying a reverse voltage to the bias signal S12.
The IN diode D12 is turned off to turn on P1 → P2, the reverse voltage is applied to the bias signal S21 to turn off the PIN diode D21, and the forward current is passed to the bias signal S22 to turn on the PIN diode D22 to turn on P1 → Turn off P3.

FIG. 3 shows an example of a circuit to which actual design values are applied, and FIG. 4 shows the characteristics when P1 → P2 is turned on and P1 → P3 is turned off. However, in the embodiment of FIG. 4, the on-current is 100 mA and the off-voltage is -100 V.
Is a simulation result when the equivalent circuit is shown in FIG.

According to the characteristic diagram of FIG. 4, frequencies 100 to 5
At 00 MHz, the isolation of P3 → P1 was −70 to −60V. It can be seen that this is clearly better than the conventional characteristic diagram of FIG.

In FIG. 2, when P1 → P3 is turned on, a reverse voltage is applied to the bias signal S11 to turn off the PIN diode D11, and a forward current is applied to the bias signal S12 to turn on the PIN diode D12 to turn on P1. → P2 is turned off, a forward current is applied to the bias signal S21 to turn on the PIN diode D21, and a reverse voltage is applied to the bias signal S22 to turn off the PIN diode D22 and turn on P1 → P3. This allows input P1
The RF signal of the output P3 can be selected to the RF signal line of the output P3, and the isolation of the RF signal line of the output P2 that is turned off can be improved.

[0023]

As described above, according to the present invention, it becomes possible to approach a more ideal RF switch by improving the isolation. Also, the RF in the off state
The impedance of the signal line less affects the RF signal line in the ON state.

[Brief description of drawings]

FIG. 1 is an RF switch circuit diagram of an embodiment of the present invention.

FIG. 2 is an RF signal selector circuit diagram according to an embodiment of the present invention.

FIG. 3 is a circuit diagram in which actual numerical values are applied to FIG.

FIG. 4 is a characteristic diagram of the circuit example of FIG.

FIG. 5 is a conventional RF switch circuit diagram.

FIG. 6 is a conventional RF signal selector circuit diagram.

FIG. 7 is a circuit diagram in which actual numerical values are applied to FIG.

FIG. 8 is a characteristic diagram of the circuit example of FIG. 7.

FIG. 9 is an equivalent circuit diagram of a PIN diode.

[Explanation of symbols]

P1 ... RF signal input, P2, P3 ... RF signal output, D
1, D2, D11, D12, D21, D22 ... PIN diode, CIN, CIN1, CIN2, C1, COU
T1, COUT2 ... Capacitors, L1, L2, L3, L
11, L12, L13, L21, L22, L23 ... Coil, S1, S2, S11, S12, S21, S22 ... Bias signal, GND ... Ground.

Claims (2)

[Claims] 1. A PIN diode D1, an input circuit of a bias signal S1 for controlling ON / OFF of the PIN diode D1, and an RF passing through the PIN diode D1.
In the RF switch composed of a capacitor and a coil for insulating a signal from the bias signal S1, the P switch
On the output side of the IN diode D1, another PIN diode D2, an input circuit of a bias signal S2 for controlling ON / OFF of the PIN diode D2, an RF signal passing through the PIN diode D2 and the bias signal S2 are isolated. And a bias coil S1, which reversibly applies the bias signal S2 to the bias signal S1.
An RF switch comprising a short circuit for dropping an RF signal passing when the IN diode D1 is turned off to the ground GND through the PIN diode D2. 2. A PIN diode D1, an input circuit of a bias signal S1 for controlling ON / OFF of the PIN diode D1, and an RF passing through the PIN diode D1.
Another PIN diode D2 is provided on the output side of the PIN diode D1 of the RF switch composed of a capacitor and a coil for insulating a signal from the bias signal S1.
The bias signal S2 comprises an input circuit for controlling the ON / OFF of the PIN diode D2, a capacitor and a coil for insulating the RF signal passing through the PIN diode D2 from the bias signal S2, and the bias signal S2.
Is reversibly added to the bias signal S1 and the RF signal passing when the PIN diode D1 is turned off is PIN
At least two RF switch circuits provided with a short circuit that drops to the ground GND through the diode D2 are provided on the RF signal line in combination, and the RF signal line is selected by controlling the bias signals S1 and S2 of the RF switch circuits. An RF signal selector characterized in that