JP2013186047A - Termination circuit and test device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive termination circuit having good frequency response up to a high frequency range.SOLUTION: A termination circuit and a test device are provided. The termination circuit includes a termination resistor having one end connected to an end of a transmission line, a first capacitor connected between the other end of the termination resistor and reference potential, a relay having one end connected to the other end of the termination resistor, and a second capacitor which has larger capacitance than the first capacitor and is connected between the other end of the relay and the reference potential. The termination circuit may include a reference voltage supply unit connected to the other end of the relay to supply reference voltage from the other end of the relay to the transmission line via the relay and the termination resistor.

Description

  The present invention relates to a termination circuit and a test apparatus.

2. Description of the Related Art Conventionally, when testing a device under test that does not include a termination circuit, a test apparatus that tests the device under test uses a termination circuit that matches impedance in addition to a test head on which the device under test is placed. (For example, refer to Patent Document 1).
Patent Document 1 JP 2003-156528 A Patent Document 2 JP 2010-268213 A

  Such a termination circuit terminates a transmission line while supplying a termination voltage to the transmission line when a test using a high-frequency signal is executed. The termination circuit has a switch that cuts off the supply of the termination voltage, and cuts off the supply of the termination voltage when performing a DC test using a DC voltage or a relatively low frequency. Therefore, when the transmission speed of the signal transmitted and received by the test apparatus is increased, it is necessary to terminate the high-speed signal through the switch, and an expensive switch corresponding to the high-speed signal has to be used.

  In the first aspect of the present invention, a termination resistor having one end connected to the end of the transmission line, a first capacitor unit connected between the other end of the termination resistor and the reference potential, and one end of the termination resistor Provided is a termination circuit and a test apparatus including a relay connected to the other end, and a second capacitor unit having a larger capacity than the first capacitor unit, which is connected between the other end of the relay and a reference potential.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

A configuration example of a test apparatus 100 according to the present embodiment is shown together with a device under test 10. The structural example of the termination | terminus part 200 which concerns on this embodiment is shown. The modification of the termination | terminus part 200 which concerns on this embodiment is shown.

  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 test apparatus 100 according to this embodiment together with a device under test 10. The device under test 10 has a plurality of input / output terminals or input / output electrodes that exchange electric signals with the outside. The test apparatus 100 tests a device under test 10 such as an analog circuit, a digital circuit, a memory, and a system on chip (SOC).

  The test apparatus 100 inputs a test signal based on a test pattern for testing the device under test 10 to the device under test 10 and based on an output signal output from the device under test 10 according to the test signal. 10 pass / fail is determined. The test apparatus 100 includes a test unit 110, a test head unit 120, a reference voltage supply unit 130, and a termination unit 200.

  The test unit 110 tests the device under test 10 by exchanging electrical signals with the device under test 10. The test unit 110 transmits a test signal to the device under test 10 via the test head unit 120 and receives a response signal corresponding to the test signal. The test unit 110 includes a test signal generation unit 112, an expected value comparison unit 114, and one or a plurality of signal input / output units 116.

  The test signal generator 112 is connected to one or more devices under test 10 via the signal input / output unit 116 and generates a plurality of test signals to be supplied to the device under test 10. The test signal generator 112 may generate a test signal for each input / output terminal of the device under test 10. The test signal generator 112 may generate an expected value of the response signal output from the device under test 10 according to the test signal.

  The expected value comparing unit 114 compares the data value included in the response signal of the device under test 10 received from the signal input / output unit 116 with the expected value generated by the test signal generating unit 112. The expected value comparison unit 114 determines pass / fail of the device under test 10 based on the comparison result.

  The signal input / output unit 116 transmits the test signal generated by the test signal generation unit 112 to the device under test 10 via the test head unit 120. Further, the signal input / output unit 116 receives a response signal output from the device under test 10 according to the test signal. The signal input / output unit 116 converts the received response signal of the device under test 10 into a data value and transmits it to the expected value comparison unit 114.

  When the test unit 110 includes a plurality of signal input / output units 116, the plurality of signal input / output units 116 are respectively connected to different input / output terminals of the device under test 10 and received from the test signal generation unit 112. Each test signal is transmitted. Further, the plurality of signal input / output units 116 respectively receive a plurality of response signals output from the device under test 10 according to the test signal, and transmit them to the expected value comparison unit 114. Here, the plurality of signal input / output units 116 may be respectively connected to different input / output terminals of the plurality of devices under test 10 to exchange signals.

  The test head unit 120 mounts one or a plurality of devices under test 10. The test head unit 120 may include a performance board on which one or a plurality of devices under test 10 are mounted. The test head unit 120 is connected to each of the one or more signal input / output units 116, and the one or more signal input / output units 116 and one or more input / output terminals of the one or more devices under test 10 are in a one-to-one relationship. Each may be connected to send and receive signals.

  The reference voltage supply unit 130 is connected to the termination unit 200 and supplies a reference voltage to the termination unit 200. The reference voltage supply unit 130 may set the reference voltage to a predetermined voltage. Alternatively, the reference voltage supply unit 130 may set the reference voltage according to the type of test performed by the test unit 110. For example, the reference voltage is a termination voltage of a response signal output from the device under test 10.

  The termination unit 200 is connected to an input / output terminal of the device under test 10 that does not include a termination circuit, and terminates the input / output terminal. A plurality of termination units 200 may be provided in the test apparatus 100 and connected to a plurality of input / output terminals of one or a plurality of devices under test 10, respectively. In this case, the same number of termination units 200 as the plurality of signal input / output units 116 are provided in the test apparatus 100 and connected to the plurality of input / output terminals of the device under test 10 to which the plurality of signal input / output units 116 are connected. It is desirable.

  Termination unit 200 may be a termination board having a connector and connected to test head unit 120 via a cable via the connector. Details of the termination unit 200 will be described with reference to FIG.

  The termination unit 200 is connected to an input / output terminal of the device under test 10 via a transmission line. The termination unit 200 is connected to the test head unit 120 through a transmission line such as a coaxial cable, and a high frequency signal of several MHz or more may be transmitted. Here, the transmission line such as a coaxial cable has a length not less than a predetermined length that is not less than the distance between the terminal portion 200 and the test head portion 120, and reduces the high-frequency component of the signal to be transmitted. It may have a low-pass filter function.

  The transmission path may include a low pass filter. As a result, the transmission line can reduce in advance the high-frequency component to be terminated by the termination unit 200, and can reduce the reflection component even when the signal component is reflected from the termination unit 200.

  In this embodiment, the transmission path from the test unit 110 to the test head unit 120 and the transmission path from the test head unit 120 to the termination unit 200 may have substantially the same characteristic impedance. As an example, the two transmission lines are coaxial cables having a characteristic impedance of 50Ω.

  FIG. 2 shows a configuration example of the termination unit 200 according to the present embodiment. The termination unit 200 has a device side terminal 202, a power supply side terminal 204, and a reference potential 206, and a termination circuit is provided between the device side terminal 202 and the power supply side terminal 204. Here, the device side terminal 202 is connected to the test head unit 120, and the power source side terminal 204 is connected to the reference voltage supply unit 130. The device-side terminal 202 and the output terminal may be provided with a connector or the like. The reference potential 206 is a GND potential of 0V, for example. The termination circuit includes a termination resistor 210, a first capacitor unit 220, a relay 230, and a second capacitor unit 240.

  One end of the termination resistor 210 is connected to the end of the transmission line. Here, the transmission line is connected to the device-side terminal 202 at the end opposite to the end to which the termination resistor 210 is connected. That is, the terminal resistor 210 has one end connected to the device side terminal 202 and the other end connected to the relay 230 between the device side terminal 202 and the power source side terminal 204.

  The termination resistor 210 has a resistance value substantially the same as the characteristic impedance of the transmission line from the test head unit 120 to the termination unit 200, and terminates the transmission line to reduce the reflected signal to the transmission line. As an example, the termination resistor 210 has a resistance value of 50Ω. In this case, the termination resistor 210 may connect two 100Ω resistors in parallel to form a resistance value of 50Ω.

  The first capacitor unit 220 is connected between the other end of the termination resistor 210 and the reference potential 206. That is, the first capacitor unit 220 is provided between the transmission line connecting the termination resistor 210 and the relay 230 and the reference potential 206. The first capacitor unit 220 passes the high frequency component of the signal input to the termination unit 200 to the reference potential 206 side. The first capacitor unit 220 passes a signal in at least a part of the frequency band outside the pass frequency band of the relay 230 in the signal received from the transmission line side to which the termination resistor 210 is connected, to the reference potential 206 side.

  For example, the first capacitor unit 220 and the termination resistor 210 form a low-pass filter having a cutoff frequency based on the time constant of the product of the capacitance value and the resistance value. As an example, the first capacitor unit 220 may form a low-pass filter having a capacitance value of about 1000 pF and a cutoff frequency of about several MHz. The first capacitor unit 220 further includes one or more capacitors having a capacitance value smaller than 1000 pF so that high-frequency components of several tens, hundreds, and several GHz or more pass to the reference potential 206 side. One or more capacitors may be connected to the first capacitor unit 220 in parallel.

  That is, the first capacitor unit 220 connects a plurality of capacitors having self-resonant frequencies on the high frequency side of several tens, hundreds, or GHz, so that more components above the self-resonant frequency are on the reference potential 206 side. Can be passed. As an example, the first capacitor unit 220 has capacitors of about 1000 pF, 100 pF, 10 pF, and 1 pF, and is connected in parallel between the termination resistor 210 and the reference potential 206, respectively.

  The relay 230 has one end connected to the other end of the termination resistor 210 and the other end connected to the power supply side terminal 204. The relay 230 switches between interruption and conduction between the device side terminal 202 and the power supply side terminal 204. The relay 230 includes, in the pass band, at least a part of the remaining signal band obtained by subtracting the signal band that the first capacitor unit 220 passes to the reference potential 206 side from the signal component input from the device side terminal 202. It's okay.

  As an example, when the first capacitor unit 220 passes a signal band of about several MHz or more to the reference potential 206 side, the relay 230 passes an AC signal component of about several MHz or less to the reference potential 206 side. The relay 230 may include an optical semiconductor switch. Instead, the relay 230 may be a mechanical switch such as a reed relay or a mercury relay that mechanically switches between conduction and non-conduction.

  The second capacitor unit 240 is connected between the other end of the relay 230 and the reference potential 206, and has a larger capacitance value than the first capacitor unit 220. That is, the second capacitor unit 240 is provided between the transmission line connecting the relay 230 and the power supply side terminal 204 and the reference potential 206.

  When the relay 230 is in a conductive state, the second capacitor unit 240 allows an AC component of signal components transmitted from the relay 230 to pass to the reference potential 206 side. For example, when the first capacitor unit 220 passes a signal component of about several MHz or more of the signal components input from the device-side terminal 202 to the reference potential 206 side, the second capacitor unit 240 is transmitted from the relay 230. AC signal components of about several MHz or less are transmitted to the reference potential 206 side.

  Here, the power supply side terminal 204 is connected to the reference voltage supply unit 130, the reference voltage supply unit 130 is connected to the other end of the relay 230, and the relay 230 and the termination resistor 210 are connected from the other end of the relay 230. A reference voltage is supplied to the transmission line connected to the device side terminal 202.

  The termination unit 200 terminates a transmission line connected to the device side terminal 202. For example, the termination unit 200 terminates a transmission line connected to the device side terminal 202 by supplying a reference voltage to the transmission line when the test unit 110 performs a test using a high-frequency signal of several MHz or higher. Further, when the test unit 110 executes a DC test or a test using a relatively low-speed test signal of about several MHz or less, the reference voltage supplied to the transmission line by the reference voltage supply unit 130 may be cut off.

  Termination unit 200 uses relay 230 to switch off and supply of the reference voltage. For example, the relay 230 conducts between the device side terminal 202 and the power supply side terminal 204 when the test unit 110 performs a test using a high frequency signal of about several MHz or more. Thus, the termination unit 200 transmits a reference voltage, which is a termination voltage, while passing a component of a high frequency signal of about several MHz or more input from the transmission line connected to the device side terminal 202 to the reference potential 206 side. Can be supplied to the road.

  Moreover, the relay 230 interrupts | blocks between the device side terminal 202 and the power supply side terminal 204, when the test part 110 performs DC test etc. FIG. Accordingly, the termination unit 200 can prevent the reference voltage supplied from the reference voltage supply unit 130 from affecting the DC test or the like. As described above, the termination unit 200 attenuates a high-frequency signal that is reflected in the direction of the transmission path connected to the device-side terminal 202 and affects the waveform quality in accordance with the test performed by the test unit 110. The supply of the reference voltage to the transmission line can be switched while terminating.

  The termination unit 200 can perform such switching by switching a relatively low-speed signal of, for example, about several MHz or less. That is, the termination unit 200 can switch the supply of the reference voltage using an inexpensive relay 230 that switches a signal of about several MHz or less while terminating a component of a high-frequency signal of about several MHz or more.

  Here, the transmission path from the transmission path connected to one end of the termination resistor 210 to one end of the relay 230 may be formed of a waveguide. That is, the transmission line from the device side terminal 202 to the relay 230 and the transmission line connected to the reference potential 206 from the transmission line via the first capacitor unit 220 are formed by forming a distributed constant circuit on the substrate, for example. It is formed of a waveguide that transmits a high-frequency signal of about MHz or higher.

  The waveguide may be formed of a microstrip line, or may be formed of a coplanar line instead. Alternatively, the waveguide may be a strip line or a parallel line. As described above, the termination unit 200 is configured by using the transmission line from the device-side terminal 202 to the relay 230 and the transmission line connected to the reference potential 206 from the transmission line via the first capacitor unit 220 as a waveguide. The generation of reflected waves can be reduced and high frequency signals of several MHz or more can be terminated.

  Here, since the termination unit 200 transmits a frequency signal of about several MHz or less in the transmission path after the relay 230, it is not necessary to form a distributed constant circuit. Therefore, the termination part 200 can improve design efficiency by making a region designed as a waveguide a part of the termination circuit. In addition, the termination unit 200 can use passive circuit components as the termination resistor 210 and the first capacitor unit 220, and by arranging smaller components than the relay 230, the design area of the waveguide can be extended to the entire termination circuit. The area can be made narrower than that.

  FIG. 3 shows a modification of the termination portion 200 according to the present embodiment. In the end portion 200 of the present modification, the same reference numerals are given to substantially the same operations as those of the end portion 200 according to the present embodiment shown in FIG. The terminal portion 200 of this modification further includes a resistance portion 310.

  The resistor unit 310 is connected in series with the first capacitor unit 220 between the other end of the termination resistor 210 and the relay 230 and the reference potential 206. The resistor unit 310 may have one end connected to the termination resistor 210 and the other end connected to one end of the first capacitor unit 220. In this case, the other end of the first capacitor unit 220 is connected to the reference potential 206. Instead, the resistor 310 may have one end connected to the other end of the first capacitor unit 220 and the other end connected to the reference potential 206. In this case, one end of the first capacitor unit 220 is connected to the termination resistor 210.

  The sum of the resistance value of the resistance unit 310 and the resistance value of the termination resistor 210 is substantially equal to the termination resistance value of the transmission line connected to the device-side terminal 202. That is, the sum of the resistance value of the resistance unit 310 and the resistance value of the termination resistor 210 according to this modification is equal to the resistance value of the termination resistor 210 in the embodiment described with reference to FIG. Therefore, the termination unit 200 according to the present modification generates a reflection of a signal component transmitted from the device-side terminal 202 to the reference potential 206 via the resistor unit 310 and the first capacitor unit 220. Reduce and terminate.

  Here, the resistance value of the resistance unit 310 is designed to be approximately equal to the total internal resistance of the circuit elements connected after the relay 230. For example, in this modification, the resistance value of the resistance unit 310 is equal to the internal resistance value of the relay 230. As an example, when the internal resistance value of the relay 230 is 1Ω, the resistance value of the resistance unit 310 is designed to be 1Ω, and the resistance value of the termination resistor 210 is designed to be 49Ω. That is, the termination resistance of the transmission line that transmits to the reference potential 206 via the termination resistor 210, the relay 230, and the second capacitor unit 240 is also substantially equal to the termination resistance value of the transmission line connected to the device-side terminal 202. can do.

  As a result, the termination unit 200 generates a reflection of a signal component transmitted from the device-side terminal 202 to the reference potential 206 via the termination resistor 210, the relay 230, and the second capacitor unit 240. Can be terminated.

  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.

10 device under test, 100 test apparatus, 110 test unit, 112 test signal generation unit, 114 expected value comparison unit, 116 signal input / output unit, 120 test head unit, 130 reference voltage supply unit, 200 termination unit, 202 device side terminal , 204 power supply side terminal, 206 reference potential, 210 terminal resistance, 220 first capacitor unit, 230 relay, 240 second capacitor unit, 310 resistor unit

Claims (12)

A terminating resistor whose one end is connected to the end of the transmission line;
A first capacitor connected between the other end of the termination resistor and a reference potential;
A relay having one end connected to the other end of the termination resistor;
A second capacitor unit having a larger capacity than the first capacitor unit, connected between the other end of the relay and the reference potential;
A termination circuit comprising:   The termination circuit according to claim 1, further comprising a reference voltage supply unit that is connected to the other end of the relay and supplies a reference voltage to the transmission line from the other end of the relay via the relay and the termination resistor.   3. The termination circuit according to claim 1, wherein the first capacitor unit passes a signal in at least a part of a frequency band outside a pass frequency band of the relay in a signal received from the transmission line side to the reference potential side. .   4. The termination circuit according to claim 1, wherein a transmission path from the transmission path connected to one end of the termination resistor to one end of the relay is formed of a waveguide. 5.   The termination circuit according to claim 4, wherein the waveguide is formed of a microstrip line.   The termination circuit according to claim 4, wherein the waveguide is formed of a coplanar line. A transmission line between the other end of the termination resistor and the relay, and a resistance unit connected in series with the first capacitor unit between the reference potential and
7. The termination circuit according to claim 1, wherein a sum of a resistance value of the resistance unit and a resistance value of the termination resistor is substantially equal to a termination resistance value of the transmission line.   The termination circuit according to claim 7, wherein a resistance value of the resistance unit is equal to an internal resistance value of the relay.   The termination circuit according to claim 1, wherein the relay includes an optical semiconductor switch. A test apparatus for testing a device under test,
A test unit for exchanging electrical signals with the device under test to test the device under test;
A test head unit for mounting the device under test;
The termination circuit according to any one of claims 1 to 9, which is connected to a terminal of the device under test via a transmission line;
A test apparatus comprising:   The test apparatus according to claim 10, wherein connection of the relay included in the termination circuit is switched according to a type of test of the device under test. When the test unit performs a DC test of the device under test, the relay disconnects the connection,
The test apparatus according to claim 11, wherein when the test unit executes a test of the device under test using a frequency signal, the relay makes a connection conductive.

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