JP6202975B2 - Switch device and test device - Google Patents

Description

  The present invention relates to a switch device and a test device.

Conventionally, a semiconductor switch such as a field effect transistor (FET) may be used as a switch device that switches between passing and blocking an electric signal. Such a semiconductor switch supplies a driving voltage obtained by shifting the reference voltage according to a voltage input from the outside to the gate of the main switch, thereby expanding a voltage range of an electric signal that is passed and cut off by the switch. (For example, refer to Patent Document 1).
Patent Document 1 JP2012-129939A

  However, when such a semiconductor switch is in an off state and an externally input voltage becomes excessive, even if the main switch is kept in an off state, a current is sent to the control circuit side that transmits a control signal to the main switch. May flow in and the switch device as a whole may not be able to maintain the off state.

  According to a first aspect of the present invention, there is provided a switch device that electrically connects or disconnects between a first terminal and a second terminal in accordance with a control voltage input from the outside, wherein the first terminal and the second terminal Based on the voltage from the first terminal, the main switch that is connected between the main switch that is turned on or off according to the difference between the input voltage input to the switch device and the gate voltage, and the voltage from the first terminal An on-voltage generator that generates an on-voltage that turns on the main switch, an off-voltage generator that generates an off-voltage that turns off the main switch, and a first terminal and the on-voltage generator, Provided are a switch device including a first inflow prevention unit for preventing current inflow from one terminal to an on-voltage generation unit, and a test apparatus provided with the switch.

  The summary of the invention does not enumerate all the features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

The structural example of the switch apparatus 10 which concerns on this embodiment is shown. 2 shows a configuration example of a buffer circuit 20 according to the present embodiment. The 1st modification of the switch apparatus 10 which concerns on this embodiment is shown. The 2nd modification of the switch apparatus 10 which concerns on this embodiment is shown. A configuration example of a test apparatus 200 according to the present embodiment is shown together with a device under test 300.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows a configuration example of a switch device 10 according to the present embodiment. The switch device 10 prevents the current from flowing into the control circuit side even when the voltage input from the outside becomes excessive, and between the first terminal and the second terminal according to the control voltage input from the outside. Connect or disconnect electrically. The switch device 10 includes a main switch 100, an on-voltage generation unit 110, an off-voltage generation unit 120, a control unit 130, a first inflow prevention unit 140, a second inflow prevention unit 142, and a first voltage supply unit. 150 and a second voltage supply unit 152.

  The main switch 100 is connected between the first terminal and the second terminal, and is turned on or off according to the difference between the input voltage input to the switch device and the gate voltage. For example, the main switch 100 includes a semiconductor switch such as an FET whose source and drain are connected between a first terminal and a second terminal. The main switch 100 may include a plurality of FETs. In this case, the main switch 100 may be connected in series between the first terminal and the second terminal.

  The main switch 100 may be a depletion type FET, and may instead be an enhancement type FET. The main switch 100 may be an FET formed of a compound semiconductor, and is a GaN-HEMT as an example.

  In the present embodiment, the source of the main switch 100 will be described as a terminal to which a carrier is supplied out of a terminal connected to the first terminal and a side connected to the second terminal. For example, when the main switch 100 is an N-channel FET and the first terminal voltage is higher than the second terminal voltage, the current flows in the direction from the first terminal to the second terminal, and the carrier (electron) ) Is supplied from the second terminal side to the first terminal side. Therefore, in this case, the terminal on the second terminal side of the FET is used as the source. Here, when the main switch 100 is an N-channel FET and the first terminal voltage is smaller than the second terminal voltage, the current flows in the opposite direction, so that the first terminal side of the FET is The terminal is the source.

  In the main switch 100, the difference between the lower voltage and the gate voltage of the input voltages input from the first terminal or the second terminal is the gate-source voltage, and the main switch 100 is turned on or off according to the gate-source voltage. Turn off. The main switch 100 receives the on-voltage generated by the on-voltage generator 110 and turns on, and receives the off-voltage generated by the off-voltage generator 120 and turns off.

  The on-voltage generation unit 110 receives voltages from the first terminal and the second terminal, and generates an on-voltage that turns on the main switch 100 based on the voltages from the first terminal and the second terminal. For example, the on-voltage generation unit 110 generates an on-voltage based on a lower voltage among the voltage at the first terminal and the voltage at the second terminal. The on-voltage generation unit 110 includes a first buffer unit 112, a second buffer unit 114, a comparison unit 116, and a third buffer unit 118.

  The first buffer unit 112 receives an input voltage input from the first terminal, and outputs the received voltage to the comparison unit 116. For example, the first buffer unit 112 has a current amplification function (that is, a buffer function) so that the input voltage input from the first terminal is hardly reduced (so that the input voltage hardly becomes a load). In addition, the first buffer unit 112 has a voltage limit function that outputs a predetermined voltage when the input voltage input from the first terminal is larger (smaller) than a predetermined voltage. May be.

  The second buffer unit 114 receives an input voltage input from the second terminal, and outputs the received voltage to the comparison unit 116. Similar to the first buffer unit 112, the second buffer unit 114 may have a current amplification function and / or a voltage limit function. The second buffer unit 114 may be configured by a circuit that is substantially the same as the first buffer unit 112.

  The comparison unit 116 is connected to the first buffer unit 112 and the second buffer unit 114, receives the voltage at the first terminal and the voltage at the second terminal, and outputs a voltage corresponding to the received two voltages. As an example, the comparison unit 116 compares the voltage at the first terminal and the voltage at the second terminal, and outputs the lower voltage.

  The third buffer unit 118 is connected to the comparison unit 116, receives the output voltage output from the comparison unit 116, and outputs the received voltage as an ON voltage that turns on the main switch 100. The third buffer unit 118 may have a current amplification function and / or a voltage limit function, like the first buffer unit 112 and the like. In addition, the third buffer unit 118 may be configured by substantially the same circuit as the first buffer unit 112 and the like.

  The off voltage generator 120 generates an off voltage that turns off the main switch 100. The off-voltage generating unit 120 turns off the main switch 100 according to the characteristics of the FET used for the main switch 100 and the minimum voltage value or the maximum voltage value of the voltage applied to the first terminal and the second terminal. A predetermined voltage is output.

  The control unit 130 is connected to the third buffer unit 118 and the off voltage generation unit 120 of the on voltage generation unit 110, respectively, and receives an on voltage and an off voltage for turning on / off the main switch 100. The control unit 130 is connected to the gate of the main switch 100 and supplies a gate voltage based on the on voltage or the off voltage to the main switch 100 according to the control voltage.

  For example, the control unit 130 has a switch function of outputting either an on-voltage or an off-voltage according to a control voltage input from the outside. The control unit 130 outputs an off voltage when the control voltage input from the outside is a high voltage, and outputs an on voltage when the control voltage input from the outside is a low voltage. It may have an inverter function for inverting.

  In the switch device 10 according to the present embodiment described above, when the main switch 100 is turned off according to the control voltage from the outside, the control unit 130 supplies the off voltage to the gate of the main switch 100. Here, as an example, the main switch 100 is an N-channel depletion type that is completely turned on when the gate-source voltage is −6 V or more and completely turned off when the gate-source voltage is −9 V or less. The description will be made assuming that the minimum voltage value of the voltage applied to the first terminal and the second terminal is 0V.

  In this case, for example, the off-voltage generation unit 120 generates and outputs a voltage of −14V as the off-voltage. Thereby, even if the voltage applied to the first terminal and the second terminal becomes the minimum voltage value, the switch device 10 has the gate-source voltage of the main switch 100 set to -14V and is completely turned off. Can do.

  In addition, when the switch device 10 turns on the main switch 100 according to a control voltage from the outside, the control unit 130 supplies the on voltage to the gate of the main switch 100. For example, the on-voltage generation unit 110 generates a lower voltage as an on-voltage among the input voltage input to the first terminal and the input voltage input to the second terminal.

  Here, the lower voltage of the input voltage at the first terminal and the input voltage at the second terminal is on the source side of the main switch 100, so the gate-source voltage of the main switch 100 is set to approximately 0V. be able to. Even if the value of the input voltage (that is, the source voltage) fluctuates, the switch device 10 supplies the source voltage to the gate, so that the gate-source voltage of the main switch 100 can be maintained at approximately 0V. The main switch 100 can be turned on.

  As described above, the switch device 10 supplies the main switch 100 with the on-voltage and the off-voltage corresponding to the input voltages input to the first terminal and the second terminal, so that the electric signal that is passed and blocked by the main switch. The voltage range can be expanded. However, when the main switch 100 of the switch device 10 is turned off, if a voltage of, for example, about +10 V or more is input to the first terminal or the second terminal, the main switch 100 is kept off. In some cases, current flows through the on-voltage generator 110 on the control circuit side.

  That is, when such an excessive voltage is applied, since the switch device 10 has passed a current through the first terminal or the second terminal, the switch device 10 is no longer in the off state. Therefore, the switch device 10 of the present embodiment includes the first inflow prevention unit 140, the second inflow prevention unit 142, the first voltage supply unit 150, and the second voltage supply unit 152, and even if an excessive voltage is applied, It prevents current from flowing to the control circuit side.

  The first inflow prevention unit 140 is connected between the first terminal and the on-voltage generation unit 110, and prevents current from flowing from the first terminal to the on-voltage generation unit 110. The second inflow prevention unit 142 is connected between the second terminal and the on-voltage generation unit 110, and prevents current from flowing into the on-voltage generation unit 110 from the second terminal. The first inflow prevention unit 140 and the second inflow prevention unit 142 block between the first and second terminals and the on-voltage generation unit 110 when the main switch 100 is turned off.

  For example, the first inflow prevention unit 140 is connected to the control unit 130, and electrically connects the first terminal and the first buffer unit 112 by an ON voltage supplied from the control unit 130. In addition, the first inflow prevention unit 140 electrically disconnects the first terminal and the first buffer unit 112 according to the off voltage supplied from the control unit 130. The first inflow prevention unit 140 may include a semiconductor switch such as an FET. In this case, the gate electrode is connected to the control unit 130. The first inflow prevention unit 140 may have the same type or substantially the same switch as the main switch 100.

  Similarly to the first inflow prevention unit 140, the second inflow prevention unit 142 is connected to, for example, the control unit 130, and the second inflow prevention unit 142 and the second inflow prevention unit 142 correspond to the on voltage and the off voltage supplied from the control unit 130. 2 A switch for electrically connecting or disconnecting the buffer unit 114 is provided. The second inflow prevention unit 142 may include a semiconductor switch such as an FET. In this case, the gate electrode is connected to the control unit 130. The first inflow prevention unit 140 and the second inflow prevention unit 142 may be the same type or substantially the same switch as the main switch 100.

  The first voltage supply unit 150 is connected between the first inflow prevention unit 140 and the first buffer unit 112 of the on-voltage generation unit 110, and the first inflow prevention unit is between the first terminal and the on-voltage generation unit 110. In response to the interruption, a predetermined voltage is supplied to the first inflow prevention unit 140. Accordingly, when the first inflow prevention unit 140 prevents current inflow from the first terminal, the potential of the first voltage supply unit 150 between the first inflow prevention unit 140 and the first buffer unit 112 becomes indefinite. This prevents the first inflow prevention unit 140 from being stably turned off.

  As an example, when the main switch 100 and the first inflow prevention unit 140 are N-channel depletion type FETs, the first voltage supply unit 150 supplies approximately 0V. As a result, when the first inflow prevention unit 140 prevents the current inflow from the first terminal, that is, when the first inflow prevention unit 140 is turned off, the first inflow prevention unit 140 and the on-voltage generation unit 110 The potential can be made approximately 0V.

  In this case, even if the input voltage at the first terminal exceeds 0V, the first voltage supply unit 150 sets the potential on the first buffer unit 112 side of the first inflow prevention unit 140 to approximately 0V to be the source potential. Therefore, the gate-source voltage of the first inflow prevention unit 140 is set to a constant potential difference (that is, the off-voltage supplied from the control unit 130) regardless of the input voltage of the first terminal, and the first inflow prevention unit 140 is Set to stable off state.

  As described above, the first inflow prevention unit 140 can disconnect the electrical connection between the first terminal and the first buffer unit 112 according to the off voltage supplied from the control unit 130. Accordingly, when the main switch 100 is off, even if an excessive voltage (for example, +10 V or more) is input from the first terminal, the first inflow prevention unit 140 supplies the current from the first terminal to the on-voltage generation unit 110. Is prevented from flowing in, so that the switch device 10 can maintain the off state. Therefore, the switch device 10 of the present embodiment can expand the voltage range of the input voltage from the first terminal to a voltage range of 0 V to +10 V or more, for example.

  The first voltage supply unit 150 may include a series resistance element or a series resistance component having a large resistance value. Accordingly, when the first inflow prevention unit 140 is in the on state and the input voltage from the first terminal is supplied to the first buffer unit 112, the first voltage supply unit 150 is connected to the first voltage supply unit 150 side. Current can hardly flow (with little reduction in input voltage).

  Thereby, for example, when the input voltage at the first terminal is lower than the input voltage at the second terminal, the control unit 130 sets the input voltage at the first terminal as the ON voltage and the main switch 100 and the first inflow prevention unit 140. Can be supplied to the gate. That is, the main switch 100 and the first inflow prevention unit 140 can maintain a stable ON state because the gate-source voltage is substantially 0V.

  Similarly to the first voltage supply unit 150, the second voltage supply unit 152 is connected between the second inflow prevention unit 142 and the on-voltage generation unit 110, and the second inflow prevention unit 142 generates an on-voltage with the second terminal. A predetermined voltage is supplied to the second inflow prevention unit 142 in response to the disconnection from the unit 110. Accordingly, when the second inflow prevention unit 142 prevents inflow of current from the second terminal, the second voltage supply unit 152 has a predetermined potential between the second inflow prevention unit 142 and the second buffer unit 114. To.

  Similarly to the example of the first voltage supply unit 150, the second voltage supply unit 152 supplies substantially 0 V, so that the second inflow prevention unit 142 and the second inflow prevention unit 142 are turned off when the second inflow prevention unit 142 is turned off. The potential between the buffer portions 114 can be set to approximately 0V. Therefore, like the first voltage supply unit 150, the second voltage supply unit 152 sets the gate-source voltage of the second inflow prevention unit 142 to a constant potential difference (even if the input voltage of the second terminal exceeds 0V). That is, the off voltage supplied from the control unit 130 can be turned off.

  As a result, when the main switch 100 is off, even if an excessive voltage (for example, +10 V or more) is input from the second terminal, the second inflow prevention unit 142 supplies the current from the second terminal to the on-voltage generation unit 110. Is prevented from flowing in, so that the switch device 10 can maintain the off state.

  Similarly to the first voltage supply unit 150, the second voltage supply unit 152 may include a series resistance element or a series resistance component having a large resistance value. Thereby, for example, when the input voltage at the second terminal is lower than the input voltage at the first terminal, the control unit 130 sets the input voltage at the second terminal as the ON voltage, and the main switch 100 and the second inflow prevention unit 142. Can be supplied to the gate. That is, the main switch 100 and the second inflow prevention unit 142 can maintain a stable ON state because the gate-source voltage becomes substantially 0V.

  In this case, the on-voltage is also supplied to the gate of the first inflow prevention unit 140, and the first inflow prevention unit 140 has a gate-source voltage of approximately 0 V, so that the on-voltage is similarly stable. The same applies to the case where the control unit 130 supplies the input voltage of the first terminal to the main switch 100 and the gate of the first inflow prevention unit 140 as the on voltage, that is, the on voltage is the second inflow prevention unit 142. The second inflow prevention unit 142 is stably turned on.

  Accordingly, the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142 can be turned on in accordance with the on voltage supplied from the control unit 130, and can be in the off state in accordance with the off voltage. . That is, the switch device 10 can switch the main switch 100 on and off according to the control voltage supplied from the outside regardless of the magnitude of the input voltage input to the first terminal and the second terminal. Moreover, the switch apparatus 10 can expand the range of the input voltage input into a 1st terminal and a 2nd terminal to the voltage range of 10V or more, for example.

  The on-voltage generating unit 110 of the switch device 10 according to the present embodiment has been described as an example in which the lower voltage of the first terminal voltage and the second terminal voltage is generated as the on-voltage. Alternatively, the on-voltage generator 110 may generate an on-voltage based on a midpoint voltage between the voltage at the first terminal and the voltage at the second terminal. In this case, as an example, the comparison unit 116 outputs a midpoint voltage between the voltage at the first terminal and the voltage at the second terminal.

  Here, since the drain voltage is equal to or higher than the source voltage, the voltage at the midpoint between the drain voltage and the source voltage is equal to or higher than the source voltage. Therefore, the on-voltage generating unit 110 can turn on the main switch 100 and the like by setting the gate-source voltage to 0 V or higher by setting the midpoint voltage of the drain voltage and the source voltage to the on-voltage, for example. it can.

  The main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142 of the switch device 10 according to the present embodiment described above have N-channel depletion type FETs that are turned on when the gate-source voltage is 0V. An example was explained. Alternatively, the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142 may be N-channel enhancement type FETs.

  An N-channel enhancement type FET has a higher voltage for turning the FET on and off than a depletion type FET. Therefore, the off-voltage generation unit 120 increases the off-voltage according to the characteristics of the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142, thereby completely turning off the FETs included in the off voltage generation unit 120. A voltage can be supplied.

  The on-voltage generator 110 generates, as an on-voltage, a voltage obtained by adding an offset voltage to the lower voltage of the first terminal voltage and the second terminal voltage. In this case, the on-voltage generation unit 110 may further include an offset voltage supply unit. Thus, the on-voltage generator 110 can supply an on-voltage that turns on the N-channel enhancement type FET by adding an offset voltage corresponding to the on-voltage that is higher than that of the depletion type FET. .

  The example in which the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142 of the switch device 10 of the present embodiment described above include N-channel FETs has been described. Alternatively, the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142 may include P-channel FETs.

  For example, a P-channel depletion type FET has a characteristic that the drain current increases as the gate-source voltage is reduced in the negative direction, contrary to an N-channel FET. As an example, a P-channel depletion type FET is completely turned on when the gate-source voltage is +6 V or less, completely turned off when the gate-source voltage is +9 V or more, and the first terminal and the second terminal Description will be made assuming that the maximum voltage value applied to the two terminals is 0V.

  In this case, the off-voltage generation unit 120 generates and outputs a voltage of + 14V as an off-voltage, for example. As a result, even when the voltage applied to the first terminal and the second terminal reaches the maximum voltage value, the switch device 10 has the gate-source voltage of the main switch 100 being +14 V, and can be completely turned off. it can.

  The on-voltage generator 110 generates the higher voltage of the input voltage at the first terminal and the input voltage at the second terminal as the on-voltage. Here, in the P-channel FET, when the voltage at the first terminal is larger than the voltage at the second terminal, the direction of current flow is from the first terminal to the second terminal, and carriers (holes) are supplied to the FET. The direction from the first terminal side to the second terminal side is. In this case, in this embodiment, the terminal on the first terminal side of the FET is used as the source. In addition, when the first terminal voltage is smaller than the second terminal voltage, the P-channel FET has a current flowing in the opposite direction, so that the terminal on the second terminal side of the FET is used as a source.

  The comparison unit 116 of the on-voltage generation unit 110 compares the input voltages of the first terminal and the second terminal, and outputs the higher voltage as the on-voltage, so that the gate-source between the P-channel depletion type FETs is output. The voltage can be set to approximately 0V. That is, the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142 are turned on according to the on voltage supplied from the control unit 130, and are turned off according to the off voltage.

  The main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142 may include a P-channel enhancement type FET. A P-channel enhancement type FET has a lower voltage for turning the FET on and off than a depletion type FET. Therefore, the off-voltage generating unit 120 lowers the off-voltage according to the characteristics of the P-channel enhancement type FET as in the case of the N-channel enhancement type FET, thereby preventing the main switch 100 and the first inflow prevention. The off voltage that completely turns off the part 140 and the second inflow prevention part 142 can be supplied.

  As described above, the off-voltage generation unit 120 includes the characteristics of the FETs used in the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142, and the minimum voltage value of the input voltage input to the switch device 10. Alternatively, by generating an off voltage according to the maximum voltage value, an off voltage that completely turns off the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142 can be supplied. Further, since the off-voltage generation unit 120 generates an off-voltage according to the voltage range of the input voltage, the main switch 100 and the first inflow prevention can be performed even if the input voltage range is expanded within a range that can be input to the main switch 100. The off voltage that completely turns off the part 140 and the second inflow prevention part 142 can be supplied.

  On the other hand, in the case of a P-channel enhancement type FET, the on-voltage generator 110 is set in advance to a higher one of the input voltage input to the first terminal and the input voltage input to the second terminal. A voltage obtained by reducing the voltage is generated as an on-voltage. In this way, the on-voltage generator 110 adds a negative offset voltage to the on-voltage, which is lower than that of the P-channel depletion type FET, to lower the on-voltage, thereby reducing the P-channel enhancement type FET. An on-voltage to be turned on can be supplied.

  As described above, the on-voltage generator 110 includes the characteristics of the FETs used in the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142, and the minimum voltage value of the input voltage input to the switch device 10. Alternatively, it is possible to supply an on-voltage that turns on the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142 by generating an on voltage corresponding to the maximum voltage value. Therefore, the on-voltage generator 110 turns on the main switch 100, the first inflow prevention unit 140, and the second inflow prevention unit 142 even if the input voltage range is expanded within a range that can be input to the main switch 100. An on-voltage can be supplied.

  FIG. 2 shows a configuration example of the buffer circuit 20 according to the present embodiment. Here, the buffer circuit 20 is an example of a circuit configuration of the first buffer unit 112, the second buffer unit 114, and / or the third buffer unit 118 described in FIG. The buffer circuit 20 includes a first voltage shift unit 22, a second voltage shift unit 24, and a current source unit 26.

  The first voltage shift unit 22 is connected between the reference potentials Vdd and Vss, and shifts the voltage corresponding to the current flowing between Vdd and Vss from the voltage input to the input unit. The first voltage shift unit 22 may be the same type of FET as the main switch 100 or the like, and is an N-channel depletion type FET as an example. The first voltage shift unit 22 has a gate connected to the input unit and a drain connected to Vdd. That is, the first voltage shift unit 22 shifts a voltage (a gate-source voltage) corresponding to a current flowing between the drain and the source from the gate voltage.

  The second voltage shift unit 24 is connected between the source and the output unit of the first voltage shift unit 22 and outputs a voltage shifted from the source voltage to the output unit. The second voltage shift unit 24 shifts a voltage substantially equal to the absolute value of the gate-source voltage of the first voltage shift unit 22. The second voltage shift unit 24 shifts the voltage corresponding to the current flowing through itself. For example, the second voltage shift unit 24 includes a resistance element, and shifts the voltage value calculated by multiplying the magnitude of the current flowing through the second voltage shift section 24 and the resistance value of the resistance element.

  The current source unit 26 is connected between the second voltage shift unit 24 and the reference potential Vss, and allows a constant current to flow between Vdd and Vss. For example, the current source unit 26 includes an FET and a resistor, and one end of the resistor is connected to the source of the FET, the other end is connected to the gate of the FET, and the constant current from the drain of the FET to the other end of the resistor. It is a constant current circuit for passing current.

  In the buffer circuit 20 described above, a constant current Ic (for example, 100 μA) flows between the reference potentials Vdd and Vss by the current source unit 26. In the first voltage shift unit 22, the constant current Ic flows between the drain and the source, a gate-source voltage (for example, −6.3 V) corresponding to the constant current Ic is determined, and the gate-source voltage is determined. , Shift from the voltage (ie, gate voltage) input to the input unit. As an example, when the input voltage is 0V, the first voltage shift unit 22 outputs 6.3V from the source terminal.

  The second voltage shift unit 24 shifts a voltage substantially equal to the absolute value of the gate-source voltage of the first voltage shift unit 22 according to the constant current Ic. That is, the second voltage shift unit 24 includes, for example, a resistance element having a resistance value of 63 kΩ, and shifts the voltage of 6.3 V from the source terminal of the first voltage shift unit 22. Accordingly, the second voltage shift unit 24 can output an output voltage (substantially 0 V) substantially the same as the input voltage of the input unit to the output unit.

  In the operation of the buffer circuit 20 of the present embodiment described above, since the input unit is connected to the gate of the first voltage shift unit 22, for example, the FET of the first voltage shift unit 22 is replaced with a MIS (Metal Insulator Semiconductor) gate. By forming the structure or the like, the input current for operating the buffer circuit 20 can be reduced. In addition, the buffer circuit 20 has a buffer function for outputting an output voltage substantially the same as the input voltage in a voltage range less than the voltage range between the reference potentials Vdd and Vss.

  That is, the buffer circuit 20 can execute the buffer function up to the upper limit voltage determined by the reference potential Vdd. When a voltage exceeding the upper limit voltage is input to the input unit, the buffer circuit 20 has a limiter function that outputs the upper limit voltage. Have. Similarly, the buffer circuit 20 can execute the buffer function up to the lower limit voltage determined by the reference potential Vss. When a voltage lower than the lower limit voltage is input to the input unit, the limiter function outputs the lower limit voltage. Have

  Since the buffer circuit 20 of this embodiment can have a buffer function and a limiter function with a simple configuration, even if the on-voltage generation unit 110 is formed, an increase in circuit scale can be prevented. Further, since the buffer circuit 20 can be configured by using substantially the same type of FET as the main switch 100 or the like, the circuit design and the actual circuit creation process can be simplified.

  In the buffer circuit 20 of the present embodiment, the gate-source voltage at which the FET of the first voltage shift unit 22 is half-on is temporarily shifted from the input voltage, and then the second voltage shift unit 24 The circuit shifts in a direction to return a voltage that is substantially the same as the voltage and outputs a voltage that is substantially the same as the input voltage. Therefore, by making the FET included in the buffer circuit 20 an enhancement type FET, the absolute value of the half-on gate-source voltage can be reduced. That is, since the absolute value of the shift voltage can be reduced, the absolute value of the voltage of Vss and / or Vdd can be reduced without changing the input voltage range in which the buffer function of the buffer circuit 20 can be executed.

  FIG. 3 shows a first modification of the switch device 10 according to the present embodiment. In the switch device 10 of the present modification, the same reference numerals are given to substantially the same operations as those of the switch device 10 according to the present embodiment shown in FIG. 1, and the description thereof is omitted. The switch device 10 of the present modification shows a configuration example when it is known in advance that there is a voltage input from the first terminal but no voltage input from the second terminal. The switch device 10 performs on / off switching of the main switch 100 without depending on the input voltage from the first terminal.

  Since there is no input from the second terminal side, the switch device 10 of the present modification generates an on voltage and an off voltage of the main switch 100 based on the input voltage from the first terminal side. That is, the on-voltage generating unit 110 receives a voltage from the first terminal and generates an on-voltage that turns on the main switch 100 based on the voltage from the first terminal. The on-voltage generation unit 110 includes a third voltage supply unit 154 as an example.

  The third voltage supply unit 154 is connected to the comparison unit 116 and supplies a predetermined voltage to the comparison unit 116. As an example, the third voltage supply unit 154 uses an ON voltage (for example, 0 V when the FET is an N-channel depletion type) to turn on the FET included in the main switch 100 and the first inflow prevention unit 140. To supply.

  The comparison unit 116 compares the voltage from the first terminal with the voltage supplied from the third voltage supply unit 154, and supplies the smaller voltage to the control unit 130 via the third buffer unit 118. . Accordingly, the on-voltage generator 110 receives the third voltage supply unit when the voltage from the first terminal is higher than the on-voltage that turns on the main switch 100 and the first inflow prevention unit 140. The voltage supplied from 154 is an on-voltage. Therefore, even if the voltage of the first terminal increases, the on-voltage generator 110 can turn on the gate-source voltage of the main switch 100 and the first inflow prevention unit 140 by approximately 0V.

  The on-voltage generator 110 receives a voltage from the first terminal when a voltage lower than the on-voltage that turns on the main switch 100 and the first inflow prevention unit 140 is input from the first terminal. The voltage is the on voltage. Therefore, even if the voltage at the first terminal is lowered, the on-voltage generator 110 also lowers the on-voltage according to the voltage at the first terminal, so that the gate / source of the main switch 100 and the first inflow prevention unit 140 are reduced. The voltage can be kept approximately 0V and turned on.

  Further, the off-voltage generation unit 120 generates an off-voltage substantially in the same manner as the operation of the switch device 10 according to the present embodiment shown in FIG. 1, so that the main switch 100 and the first inflow prevention unit 140 are turned off. can do. Therefore, also in the switch device 10 of the present modification, even when the input voltage from the first terminal increases when the main switch 100 is off, it is possible to prevent current from flowing in the direction of the on-voltage generator 110.

  In the switch device 10 of the present modification, the ON voltage generation unit 110 has the third voltage supply unit 154, and the example in which a predetermined voltage is supplied to the comparison unit 116 has been described. Instead, the on-voltage generator 110 may connect the second terminal and the comparator 116 and supply the voltage of the second terminal to the comparator 116.

  Accordingly, when the voltage at the first terminal becomes higher than the voltage at the second terminal, the on-voltage generator 110 sets the voltage at the second terminal to the on voltage and the voltage at the first terminal is lower than the voltage at the second terminal. Accordingly, the voltage at the second terminal can be turned on, and the gate-source voltage of the main switch 100 and the first inflow prevention unit 140 can be set to approximately 0V. In this case, the on-voltage generation unit 110 may connect the second terminal and the comparison unit 116 via the second buffer unit 114.

  FIG. 4 shows a second modification of the switch device 10 according to the present embodiment. In the switch device 10 of the present modification, the same reference numerals are given to substantially the same operations as those of the switch device 10 according to the present embodiment shown in FIG. 1, and the description thereof is omitted.

  The gate of the first inflow prevention unit 140 of this modification is connected to the output of the first buffer unit 112. As a result, the gate, source, and drain of the first inflow prevention unit 140 are substantially equal to the input voltage of the first terminal, the gate-source voltage is substantially 0 V, and the on-state is normally turned on.

  And the 1st inflow prevention part 140 interrupts | blocks between a 1st terminal and the ON voltage generation part 110 according to the voltage of a 1st terminal becoming more than a reference voltage. For example, when the voltage at the first terminal becomes excessive to the extent that the first buffer unit 112 cannot output an output voltage substantially the same as the input voltage (that is, the limit function of the first buffer unit 112 operates). The first buffer unit 112 outputs the limit voltage of the first buffer unit 112.

  That is, since the gate voltage of the first inflow prevention unit 140 becomes the limit voltage of the first buffer unit 112, it becomes a voltage different from the voltage of the first terminal that becomes the source voltage. Here, the predetermined reference voltage is 16 V, the gate-source voltage for turning off the first inflow prevention unit 140 is −6 V, and the limit voltage of the first buffer unit 112 is compared with the predetermined reference voltage. An example in which the first inflow prevention unit 140 is set to a voltage 10 V that is different from the gate-source voltage by turning off the first inflow prevention unit 140 will be described.

  In this case, when the voltage at the first terminal rises above the limit voltage (10V) of the first buffer unit 112, the first buffer unit 112 outputs the limit voltage (10V). Then, the voltage at the first terminal becomes the source voltage, and the gate-source voltage of the first inflow prevention unit 140 becomes a different value from 0V.

  When the voltage at the first terminal further exceeds the reference voltage (16 V), the potential difference between the voltage at the first terminal and the limit voltage (10 V) of the first buffer unit 112, that is, the gate of the first inflow prevention unit 140. Since the source-to-source voltage is −6 V or less, the first inflow prevention unit 140 blocks between the first terminal and the on-voltage generation unit 110. As described above, the first inflow prevention unit 140 connects and disconnects between the first terminal and the on-voltage generation unit 110 according to the voltage input from the first terminal regardless of the control voltage from the outside. be able to.

  Similarly, the gate of the second inflow prevention unit 142 of this modification is connected to the output of the second buffer unit 114. As a result, the gate, source, and drain of the second inflow prevention unit 142 are substantially equal to the input voltage of the second terminal, the gate-source voltage is substantially 0 V, and the transistor is normally turned on.

  And the 2nd inflow prevention part 142 interrupts | blocks between a 2nd terminal and the ON voltage production | generation part 110 according to the voltage of a 2nd terminal becoming more than a reference voltage. As an example, a predetermined reference voltage is 16 V, a gate-source voltage for turning off the second inflow prevention unit 142 is −6 V, and the limit voltage of the second buffer unit 114 is compared with a predetermined reference voltage. Thus, the voltage is set to 10 V, which is different by the gate-source voltage for turning off the second inflow prevention unit 142.

  Accordingly, when the voltage at the second terminal becomes equal to or higher than the reference voltage (16V), the potential difference between the voltage at the second terminal and the limit voltage (10V) of the second buffer unit 114, that is, the gate- Since the source-to-source voltage is −6 V or less, the second inflow prevention unit 142 blocks between the second terminal and the on-voltage generation unit 110. As described above, the second inflow prevention unit 142 connects and disconnects between the second terminal and the on-voltage generation unit 110 according to the voltage input from the second terminal regardless of the control voltage from the outside. be able to.

  As described above, the switch device 10 according to the present modification includes an on-voltage generator that is independent of the on / off state of the main switch 100 even if the voltage input from the first terminal and the second terminal rises. An excessive current flow into 110 can be prevented.

  FIG. 5 shows a configuration example of the test apparatus 200 according to this embodiment together with the device under test 300. The test apparatus 200 tests a device under test 300 such as an analog circuit, a digital circuit, a memory, and a system on chip (SOC). The test apparatus 200 inputs a test signal based on a test pattern for testing the device under test 300 to the device under test 300, and based on an output signal output from the device under test 300 according to the test signal. The quality of 300 is judged. The test apparatus 200 includes a test unit 202 that exchanges signals with a device under test, a switch device 10, and a switch control unit 250.

  The test unit 202 includes a test signal generation unit 210, a driver 220, a comparator 230, and a determination unit 240. The test signal generator 210 generates a test signal for testing the device under test 300 and outputs the test signal to the driver 220. Further, the test signal generation unit 210 generates an expected value corresponding to the generated test signal and outputs the expected value to the determination unit 240.

  The driver 220 supplies the test signal generated from the test signal generator 210 to the device under test 300. The comparator 230 acquires the logical value of the response signal output from the device under test 300 in response to the supply of the test signal. The determination unit 240 compares the logical value acquired by the comparator 230 with the expected value to determine pass / fail of the device under test 300.

  The switch device 10 is provided in a path between the driver 220 of the test unit 202 and the device under test 300. The switch device 10 conducts or disconnects between the driver 220 and the device under test 300 according to the voltage of the control signal supplied from the switch control unit 250. The switch control unit 250 puts the switch device 10 into a conducting state during the test by the test signal generation unit 210, and puts the switch device 10 into a disconnected state other than during the test by the test signal generation unit 210.

  For example, the switch control unit 250 transmits a control signal to the control unit 130 included in the switch device 10. The control unit 130 switches the main switch 100 on and off according to the control voltage of the received control signal.

  The above-described test apparatus 200 in the present embodiment can perform a test using the switch device 10 that switches between conduction and non-conduction, regardless of the magnitude of the voltage to be transmitted. In addition, the test apparatus 200 is configured with a FET having a small size, a long lifetime, and high reliability, and can perform a test using the switch apparatus 10 having an expanded input voltage range. Further, the test apparatus 200 reverses the direction in which the electric signal is transmitted between the case where the test signal is transmitted from the test unit 202 to the device under test 300 and the case where the response signal is received from the device under test 300 to the test unit 202. Even so, the test can be executed using the switch device 10 having the same on-resistance with respect to the same amplitude voltage.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 Switch apparatus, 20 Buffer circuit, 22 1st voltage shift part, 24 2nd voltage shift part, 26 Current source part, 100 Main switch, 110 ON voltage generation part, 112 1st buffer part, 114 2nd buffer part, 116 Comparison unit 118 Third buffer unit 120 Off-voltage generation unit 130 Control unit 140 First inflow prevention unit 142 Second inflow prevention unit 150 First voltage supply unit 152 Second voltage supply unit 154 Third Voltage supply unit, 200 test apparatus, 202 test unit, 210 test signal generation unit, 220 driver, 230 comparator, 240 determination unit, 250 switch control unit, 300 device under test

Claims (11)

A switch device that electrically connects or disconnects between the first terminal and the second terminal according to a control voltage input from the outside,
A main switch connected between the first terminal and the second terminal and turned on or off in accordance with a difference between an input voltage inputted to the switch device and a gate voltage;
An on-voltage generator that inputs a voltage from the first terminal and generates an on-voltage that turns on the main switch based on the voltage from the first terminal;
An off-voltage generator that generates an off-voltage that turns off the main switch;
A first inflow prevention unit that is connected between the first terminal and the on-voltage generation unit and prevents a current inflow from the first terminal to the on-voltage generation unit;
Equipped with a,
The first inflow prevention portion, the switch device you cut off between the first terminal and the on-voltage generator voltage depending on that becomes the reference voltage or more first terminal. The on-voltage generation unit receives voltages from the first terminal and the second terminal, and generates an on-voltage that turns on the main switch based on the voltages from the first terminal and the second terminal. And
The switch device
A second inflow prevention unit that is connected between the second terminal and the on-voltage generation unit and prevents current inflow from the second terminal to the on-voltage generation unit ;
Said second inflow prevention portion, the switch device according to claim 1 you cut off between the second terminal and the on-voltage generator voltage depending on that becomes the reference voltage or the second terminal. A switch device that electrically connects or disconnects between the first terminal and the second terminal according to a control voltage input from the outside,
A main switch connected between the first terminal and the second terminal and turned on or off in accordance with a difference between an input voltage inputted to the switch device and a gate voltage;
An on-voltage generator that inputs a voltage from the first terminal and generates an on-voltage that turns on the main switch based on the voltage from the first terminal;
An off-voltage generator that generates an off-voltage that turns off the main switch;
A first inflow prevention unit that is connected between the first terminal and the on-voltage generation unit and prevents a current inflow from the first terminal to the on-voltage generation unit;
Equipped with a,
The first inflow prevention portion, the main switch is a switch device you cut off between the first terminal and the on-voltage generator when turned off. The on-voltage generation unit receives voltages from the first terminal and the second terminal, and generates an on-voltage that turns on the main switch based on the voltages from the first terminal and the second terminal. And
The switch device
A second inflow prevention unit that is connected between the second terminal and the on-voltage generation unit and prevents current inflow from the second terminal to the on-voltage generation unit ;
Said second inflow prevention portion, the switch device according to claim 3 wherein the main switch you disconnect between the second terminal and the on-voltage generator when turned off. In response to the first inflow prevention unit and the second inflow prevention unit blocking between the first terminal and the second terminal and the on-voltage generation unit, the first inflow prevention unit and the second inflow prevention unit. The switch device according to claim 4 , further comprising a voltage supply unit that respectively supplies a predetermined voltage to the inflow prevention unit. 6. The switch device according to claim 1, further comprising a control unit that supplies a gate voltage based on the ON voltage or the OFF voltage to the main switch according to the control voltage. The switch device according to any one of claims 1 to 6, wherein the on-voltage generation unit generates the on-voltage based on a lower voltage among the voltage at the first terminal and the voltage at the second terminal. The on-voltage generator, a switch device according to any one of claims 1 to 6 for generating the ON voltage based on the voltage of the midpoint between the voltage of the first terminal and the voltage of the second terminal .   The switch device according to any one of claims 1 to 8, wherein the main switch is a depletion type GaN-HEMT.   The switch device according to any one of claims 1 to 8, wherein the main switch is an enhancement-type GaN-HEMT. A test apparatus for testing a device under test,
A test section for exchanging signals with the device under test;
The switch device according to any one of claims 1 to 10, provided in a path between the test unit and the device under test;
A test apparatus comprising:

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