JP5004781B2 - High frequency switch - Google Patents

Description

  The present invention relates to a high-frequency switch having low loss and high isolation characteristics.

  Conventionally, as this type of high-frequency switch, the first and second FETs are connected in series with respect to the signal path, and a third point is connected between the connection midpoint of the first and second FETs and the ground region. There is one in which a high-frequency switch is configured by connecting FETs (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 8-293376 (FIG. 1)

  The conventional high-frequency switch described above has a drawback in that the passage loss increases due to the on-resistance because two FETs are connected in series to the signal path. The relationship between the passage loss and the isolation is a trade-off relationship between the on-resistance and the off-capacitance of the switching element.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a high-frequency switch capable of low loss characteristics.

The high-frequency switch according to the present invention includes a first high-frequency line and an inductor connected in series between a first input / output terminal and a second input / output terminal and a ground, and the first high-frequency line. and a switching element provided between the ground between the inductor, the inductor, is obtained with the previous SL first transmission line and the RF grounding means connected to the opposite side.

  According to the present invention, since the switching element is not used in series for the signal path as in the prior art, low loss characteristics can be realized. In addition, since the off-capacitance and high-frequency line parallel resonance are used in the off state, the relationship between the passage loss and the isolation is not the trade-off relationship between the on-resistance and the off-capacitance, realizing low loss and high isolation characteristics. it can.

Embodiment 1 FIG.
1 is a circuit diagram showing a configuration of a high-frequency switch according to Embodiment 1 of the present invention. The high-frequency switch shown in FIG. 1 includes a first high-frequency line 20a and a second high-frequency line 20b connected in series between the first input / output terminal 10a and the second input / output terminal 10b and the ground. And a switching element 30 provided between the first high-frequency line 20a and the second high-frequency line 20b and between the ground. Note that an example in which a PIN diode is used as the switching element 30 is shown.

  Here, the operation of the PIN diode used as the switching element 30 will be described. When a positive voltage is applied to the anode side of the PIN diode, the PIN diode is turned on, and can be regarded as a resistance equivalently at a high frequency (hereinafter referred to as on-resistance). On the other hand, when a negative voltage is applied to the anode side, it is turned off and can be regarded as a capacitance equivalently at a high frequency (hereinafter referred to as an off capacitance).

  Next, the operation of the high frequency switch according to the first embodiment will be described. FIG. 2 shows an equivalent circuit when the PIN diode is turned on. Reference numeral 40 denotes an on-resistance of the PIN diode. When the first high-frequency line 20a has an electrical length of 180 ° × n + 90 ° (n = 0, 1, 2,...) At a required frequency, the first input / output terminal 10a and the second input / output The terminal 10b is in a passing state.

  FIG. 3 shows an equivalent circuit when the PIN diode is turned off. Reference numeral 50 denotes an off capacitance of the PIN diode. The first high-frequency line 20a has an electrical length of 180 ° × n + 90 ° (n = 0, 1, 2,...) At a required frequency, and the off-capacitance of the PIN diode loaded on the shunt. And the second high-frequency line 20b are in parallel resonance at a required frequency, the first input / output terminal 10a and the second input / output terminal 10b are cut off.

  As described above, according to the first embodiment, the switching element is not used in the series as in the conventional case for the signal path, so that low loss characteristics can be realized. In addition, since the off-capacitance and high-frequency line parallel resonance are used in the off state, the relationship between the passage loss and the isolation is not the trade-off relationship between the on-resistance and the off-capacitance, realizing low loss and high isolation characteristics. it can.

  FIG. 4 shows a configuration when the inductor 60 is used for the second high-frequency line 20b. In the configuration shown in FIG. 4, the same effect as in the first embodiment can be obtained by making the off-capacitance of the PIN diode used as the switching element 30 and the inductance of the inductor 60 resonate in parallel at a required frequency.

Embodiment 2. FIG.
FIG. 5 is a circuit diagram showing a configuration of a high-frequency switch according to Embodiment 2 of the present invention. 5, the same parts as those in FIGS. 1 to 4 are denoted by the same reference numerals, and the description thereof is omitted. As new symbols, 11 is a control voltage terminal, 21 is a bias line, and 70a to 70c are first to third high-frequency grounding means.

  According to Embodiment 3 of the present invention, the first to third high-frequency grounding means 70a to 70c can ground the high-frequency line on the same plane even when a microstrip line is used. Further, when the bias line 21 has an electrical length of 180 ° × n + 90 ° (n = 0, 1, 2,...) At a required frequency, loss in the bias circuit can be reduced.

Embodiment 3 FIG.
FIG. 6 is a circuit diagram showing a configuration of a high-frequency switch according to Embodiment 3 of the present invention. In FIG. 6, the same parts as those in FIGS. As new symbols, 20c and 20d are a third high-frequency line and a fourth high-frequency line connected in series between the first input / output terminal 10a and the second input / output terminal 10b. The line 20a and the second high-frequency line 20b are provided between the connection point of the third high-frequency line 20c and the fourth high-frequency line 20d and the ground. FIG. 6 shows an example in which a PIN diode is used as the switching element 30.

  Next, the operation of the high frequency switch according to the third embodiment will be described. FIG. 7 shows an equivalent circuit when the PIN diode used as the switching element 30 is turned on. Reference numeral 40 denotes an on-resistance of the PIN diode. The third high frequency line 20c, the fourth high frequency line 20d, and the first high frequency line 20a all have an electrical length of 180 ° × n + 90 ° (n = 0, 1, 2,...) At a required frequency. If there is, the passage between the first input / output terminal 10a and the second input / output terminal 10b is in a passing state.

  FIG. 8 shows an equivalent circuit when the PIN diode used as the switching element 30 is turned off. Reference numeral 50 denotes an off capacitance of the PIN diode. The third high frequency line 20c, the fourth high frequency line 20d, and the first high frequency line 20a all have an electrical length of 180 ° × n + 90 ° (n = 0, 1, 2,...) At a required frequency. If the off-capacitance of the PIN diode loaded in the shunt and the second high-frequency line 20b are in parallel resonance at a required frequency, the first input / output terminal 10a and the second input / output terminal 10b Is in a shut-off state.

  As described above, according to the third embodiment, the switching element is not used in the series as in the conventional case for the signal path, so that low loss characteristics can be realized. In addition, since the off-capacitance and high-frequency line parallel resonance are used in the off state, the relationship between the passage loss and the isolation is not the trade-off relationship between the on-resistance and the off-capacitance, realizing low loss and high isolation characteristics. it can.

  Further, when an inductor is used for the second high-frequency line, the same effect as that of the third embodiment can be obtained by causing the off-capacitance of the PIN diode and the inductance of the inductor to resonate in parallel at a required frequency.

Embodiment 4 FIG.
FIG. 9 is a circuit diagram showing a configuration of a high-frequency switch according to Embodiment 4 of the present invention. The high frequency switch shown in FIG. 9 is a combination of two high frequency switches similar to the configuration shown in FIG. 6. In FIG. 9, 10 is an input terminal, 10a is a first output terminal, and 10b is a second output terminal. In this example, PIN diodes are used as the switching elements 30a and 30b. Such a high-frequency switch is configured by combining at least two high-frequency switches similar to those shown in FIGS. 1, 4, and 5 as well as FIG.

  Next, the operation of the high frequency switch according to the fourth embodiment will be described. FIG. 10 shows an equivalent circuit when the first PIN diode as the switching element 30a is turned on and the second PIN diode as the switching element 30b is turned off. 40 is the on-resistance of the first PIN diode, and 50 is the off-capacitance of the second PIN diode. The first, third and fourth high-frequency lines 20a, 20c, 20d and 20a ', 20c', 20d 'all have a required frequency of 180 ° × n + 90 ° (n = 0, 1, 2,...). In the case where the electrical length is long, and the off-capacitance 50 of the second PIN diode loaded on the shunt and the second high-frequency line 20b ′ are in parallel resonance at a required frequency, the input terminal 10 and the first One output terminal 10a is in a passing state, and the input terminal 10 and the second output terminal 10b are in a blocking state.

  FIG. 11 shows an equivalent circuit when the first PIN diode as the switching element 30a is turned off and the second PIN diode as the switching element 30b is turned on. 40 is the on-resistance of the second PIN diode, and 50 is the off-capacitance of the first PIN diode. The first, third and fourth high-frequency lines 20a, 20c, 20d and 20a ', 20c', 20d 'all have a required frequency of 180 ° × n + 90 ° (n = 0, 1, 2,...). In the case where it is an electrical length and the off capacitance 50 of the first PIN diode loaded on the shunt and the second high-frequency line 20b are in parallel resonance at a required frequency, the input terminal 10 and the first The output terminal 10a is cut off and the input terminal 10 and the second output terminal 10b are passed.

  As described above, according to the fourth embodiment, the switching element is not used in the series as in the prior art for the signal path, and thus low loss characteristics can be realized. In addition, since the off-capacitance and high-frequency line parallel resonance are used in the off state, the relationship between the passage loss and the isolation is not the trade-off relationship between the on-resistance and the off-capacitance, realizing low loss and high isolation characteristics. it can.

  Although the SPDT (Single Pole Double Throw) switch has been described here, the same effect as in the fourth embodiment can be obtained even with SPNT (N = 2, 3, 4,...).

  Further, when an inductor is used for the second high-frequency lines 20b and 20b ′, the same effect as that of the fourth embodiment can be obtained by causing the off-capacitance of the PIN diode and the inductance of the inductor to resonate in parallel at a required frequency. can get.

  In the first to fourth embodiments, the case where the PIN diode is used as the switching element has been described. However, the same effect can be obtained by using other diodes, transistors, and mechanical switches. Further, by loading at least two or more in parallel, low loss and high isolation characteristics can be realized.

It is a circuit diagram which shows the structure of the high frequency switch by Embodiment 1 of this invention. FIG. 2 is an equivalent circuit diagram when a PIN diode used as the switching element 30 in FIG. 1 is turned on. FIG. 2 is an equivalent circuit diagram when a PIN diode used as the switching element 30 in FIG. 1 is turned off. It is a circuit diagram which shows the structure at the time of using the inductor 60 for the 2nd high frequency track | line 20b of FIG. It is a circuit diagram which shows the structure of the high frequency switch by Embodiment 2 of this invention. It is a circuit diagram which shows the structure of the high frequency switch by Embodiment 3 of this invention. FIG. 7 is an equivalent circuit diagram when a PIN diode used as the switching element 30 in FIG. 6 is turned on. FIG. 7 is an equivalent circuit diagram when a PIN diode used as the switching element 30 in FIG. 6 is turned off. It is a circuit diagram which shows the structure of the high frequency switch by Embodiment 4 of this invention. FIG. 10 is an equivalent circuit diagram when a first PIN diode as the switching element 30a in FIG. 9 is turned on and a second PIN diode as the switching element 30b is turned off. 10 is an equivalent circuit when the first PIN diode as the switching element 30a in FIG. 9 is turned off and the second PIN diode as the switching element 30b is turned on.

Explanation of symbols

  10a first input / output terminal, 10b second input / output terminal, 11 control voltage terminal, 20a, 20a ′ first high frequency line, 20b, 20b ′ second high frequency line, 20c, 20c ′ third high frequency line 20d, 20d ′ 4th high frequency line, 21 bias line, 30, 30a, 30b switching element, 40 ON resistance of PIN diode as switching element, 50 OFF capacity of PIN diode as switching element, 60 inductor, 70a to 70c First to third high-frequency grounding means.

Claims (4)

A first high-frequency line and an inductor connected in series between the first input / output terminal and the second input / output terminal and the ground;
A switching element provided between the first high-frequency line and the inductor and a ground;
And RF grounding means the inductor, connected to the opposite side of the front Symbol first transmission line,
High frequency switch with The high frequency switch according to claim 1,
A third high-frequency line and a fourth high-frequency line connected in series between the first input / output terminal and the second input / output terminal;
The high frequency switch, wherein the first high frequency line and the inductor are provided between a connection point of the third high frequency line and the fourth high frequency line and a ground. The high-frequency switch according to claim 1 or 2,
At least two or more of the switching elements are loaded in parallel. A high frequency switch comprising a combination of at least two high frequency switches according to any one of claims 1 to 3.

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