JP2000304815A - Device power-supply apparatus for semiconductor test device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device power supply apparatus for a semiconductor test device capable of restraining dynamic oscillation generated by a direct voltage supplied by the device power supply apparatus. SOLUTION: This device power supply apparatus for a semiconductor has a constant voltage feedback loop constituted of an inverting amplifier A1, a current buffer B1, a force line, a sense line, a sense amplifier A2, and a feedback resistor R2, and an oscillation detection circuit 60 detecting an oscillating alternating voltage with a frequency higher than the prescribed amplitude as the onset of oscillation of the constant voltage feedback loop when receiving a differential signal between both ends of the force line and the sense line. The device power supply apparatus for a semiconductor is also provided with a feedback loop condition changing means receiving an oscillation detection signal from the oscillation detection circuit 60 for switching from the present feedback loop to a different feedback loop condition and controlling with at least two kinds of loop condition switching means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a semiconductor test apparatus, and supplies a predetermined constant voltage to an IC pin (power supply pin, output pin, input pin or input / output pin) of a device under test (DUT). The present invention relates to a power supply device.
In particular, the present invention relates to a device power supply device of a semiconductor test apparatus capable of suppressing a dynamic oscillation phenomenon caused by a dynamic load impedance change caused by a dynamic load current flowing through an IC pin according to a DUT test condition.

[0002]

2. Description of the Related Art As a device power supply device of a semiconductor test device, a programmable power supply device for power supply of a device under test (DUT), for power supply of a load circuit, and for measurement is used. These are known, for example, DPS, PPS, UDC, MDC, VSI
M, which is provided with a plurality of predetermined channels corresponding to the system configuration.

Next, the prior art will be described with reference to an example of the principle configuration of the main part of the device power supply device shown in FIG. here,
The DUT is placed on a test head, for example, and a programmable device power supply 5
0 is provided, and a few meters therebetween is connected by a station cable CB having a two-core shielded wire. Since the semiconductor test apparatus is well-known and well-known in the art, the description of the configuration of the entire system is omitted.

First, a conventional configuration will be described. The principal configuration of the device power supply device is as follows: a DA converter 30, resistors R1, R2, an inverting amplifier A1, and a sense amplifier A2.
, A guard amplifier A3, a current buffer B1, an oscillation detection circuit 60, a load current measurement unit 70, a station
It comprises a cable CB and a bypass capacitor C1.

The bypass capacitor C1 is connected to decaps having different capacities depending on the device under test.
For example, a 0.1 μF ceramic capacitor and a 10 μF electrolytic capacitor are connected in parallel and used. still,
An electrolytic capacitor having a large capacity is generally connected via a switching relay.

[0006] In this device power supply device, the voltage at the DUT terminal point becomes a constant predetermined voltage Vset as shown in FIG. 5C even if there is a transient load current fluctuation as shown in FIG. 5A. Power supply voltage V1 (FIG. 5B
Need to be supplied). That is, even if there is a change in the type of the DUT or the load current (from several μA to several A), it is required to always perform the follow-up control and maintain the predetermined voltage Vset.

The station cable CB is a power cable extending several meters, for example, 5 m or more, connecting the device power supply device 50 on the main body side of the semiconductor test apparatus and the DUT terminal on the test head. This consists of three wires, a power supply line CBf (force line), a sensing line CBs (sense line), a shield line CBg,
Circuit ground connection line. There is a line resistance due to the power supply line CBf and the relay connector, which causes a voltage drop (see FIG. 5D) proportional to the load current amount. For example, when the line resistance of the power supply line CBf is 0.1Ω and a load current of 1 amp flows, a voltage drop of 100 mV occurs. Therefore, the power supply line CBf is a dedicated line for supplying a power supply current, and the sensing line CBs is a DUT.
It is a dedicated line for sensing the voltage at the terminal point. In the shield line CBg, both the power supply line CBf and the sensing line CBs shield (shield) noise interference from another cable, and the distribution between the shield line CBg and the force line and the sense line. The capacity is equivalently reduced. Further, although the circuit ground connection line is connected by a relatively thick electric wire, a voltage drop occurs due to a power supply current of the DUT and the like, and an inductance component Lg of the line becomes an influence factor of the feedback control.

The DA converter 30 receives the digital code data and supplies a corresponding analog reference voltage signal to the inverting amplifier A1 via the resistor R1.

The inverting amplifier A1, the resistors R1 and R2, and the sense amplifier A2 receive the reference voltage signal of the DA converter 30 and supply a voltage signal A1s amplified to a predetermined voltage to the current buffer B1. At this time, in order to perform feedback control so that the voltage of the DUT terminal always becomes a constant predetermined voltage regardless of the fluctuation of the load current, a voltage signal from the DUT terminal point is received by the dedicated sensing line CBs described above. Is received and buffered by the high-impedance sense amplifier A2, and the buffered voltage signal A2s is connected to the other end of the resistor R2 to form a constant voltage feedback loop to the inverting amplifier A1.

[0010] As described above, the sense amplifier A2
A voltage signal from the UT terminal point is received by the sensing line CBs, and the buffered voltage signal A2s is supplied to one end of the resistor R2 and also to one end of the oscillation detection circuit 60.

The current buffer B1 generates a power supply voltage V1 which is current buffered to a current of up to several amperes.
This is a drive circuit of the push-pull output stage so that both sink current and source current are possible. A drive circuit capable of receiving a voltage signal A1s of the inverting amplifier A1 and operating at high speed so as to follow a transient fluctuation on the load side with a predetermined high-speed settling time. The power supply voltage V1 thus buffered is supplied to the DUT terminal via the series resistor R3 and the power supply line CBf. The power supply voltage V
1 is also supplied to one end of the load current measuring unit 70. The other end of the series resistor R3 is connected to the other end of the load current measurement unit 70,
It is also supplied to the other end of the oscillation detection circuit 60.

The load current measuring section 70 is a DUT to be tested.
This is a current measuring means for measuring the amount of load current (source current / sink current) flowing through the terminal, and receives a potential difference between both ends of the series resistor R3 to measure a current amount from ± several μA to ± several A with predetermined measurement accuracy and measurement. It is measured at the resolution. As shown in FIG. 5E, if the current is measured during the period in which the dynamic oscillation phenomenon occurs, the measurement cannot be performed with a predetermined measurement accuracy. In the configuration example of FIG. 4, a simple example in which only one series resistor R3 is provided is shown. However, a configuration in which a plurality of resistors are provided and a desired series resistance value can be switched according to a measurement range is provided. is there. Further, some types of device power supply devices do not include the load current measurement unit 70.

The oscillation detection circuit 60 includes: a load condition of the DUT;
With a variety of different load current fluctuation conditions, device test conditions, and the like, a rare oscillation phenomenon such as a parasitic oscillation of a feedback loop system is detected, and the detected oscillation detection signal (ALA) is detected.
(RM) 60s to the system. FIG. 5 shows an example of the detection operation. If the power supply voltage V1 at the output terminal of the current buffer B1 temporarily causes a dynamic oscillation phenomenon (see FIG. 5E) during a certain period due to dynamic fluctuation of some load condition, this is detected and an alarm ( ALARM) signal (see FIG. 5F). In response, the system recognizes that the measurement data for the test item may not be normal. As a result, incorrect measurement data can be discarded, and the test item can be re-measured.

Next, the cause of the dynamic oscillation phenomenon associated with the station cable CB will be further described. Since the station cable CB extends for several meters, its equivalent circuit is, as shown in FIG.
f, Ls, and Lg are present, and stray capacitances (stray capacitances) Csf between lines and stray capacitances (stray capacitances) Cf and Cs between grounds are present. As a result of these,
In a feedback loop for sensing a voltage signal at a DUT terminal point, complicated phase rotation occurs in a high-frequency region. Normally, a careful design is made so as not to provide a positive feedback even in the case of such complicated phase rotation and dynamic fluctuation of a load current having a wide dynamic range from several μA to several A. Therefore, in most cases, the static oscillation phenomenon does not occur. However, even with the carefully designed feedback loop, firstly, a positive feedback condition is occasionally temporarily generated due to dynamic load current fluctuation conditions and load current fluctuation periods. Secondly, as shown in the linearity characteristic in the small load current region of the bare amplifier without feedback in FIG. 6, the bias of the complementary current buffer circuit is obtained when the large current buffer B1 is used at the small load current. Non-linearity part due to current imbalance (Fig. 6B
Occasionally, a dynamic phenomenon (refer to FIG. 5E) occurs, although temporarily.

[0015]

As described above, in the prior art, the dynamic load fluctuation is not affected by the DC voltage supplied by the device power supply device having a long station cable CB and forming a constant voltage feedback loop. Accordingly, a dynamic oscillation phenomenon may rarely occur, and at this time, measurement data may not be obtained with a predetermined measurement accuracy. This is not preferable in a semiconductor test apparatus which is required to perform a device test with a predetermined measurement accuracy. In addition, there is a problem that it is necessary to perform the test again for the test item, so that a wasteful test time is required. Therefore, an object of the present invention is to provide a device power supply device of a semiconductor test device capable of suppressing a dynamic oscillation phenomenon occurring in a DC voltage supplied by the device power supply device.

[0016]

First, in order to solve the above-mentioned problems, according to the configuration of the present invention, the DU of the device under test is
The T terminal is a power supply terminal, an output terminal, an input terminal, or an input / output terminal. The T terminal is provided with at least a force line CBf and a sense line CBs between the DUT terminal and the device power supply device, and the force line CBf is connected to the DUT terminal. A sense line CBs is a line that detects (senses) a voltage signal of the DUT terminal, and is a line that supplies a load current of a sink / source current flowing to the DUT terminal.
In a device power supply device of a semiconductor test device forming a constant voltage feedback loop for controlling the voltage of the DUT terminal to be constant by Bs, an inverting amplifier A1 and a current buffer B1 are provided.
, Force line CBf, sense line CBs, and sense amplifier A
2 and a feedback resistor R2 to form a constant voltage feedback loop,
An oscillation detection circuit 60 is provided for detecting the start of oscillation of a constant voltage feedback loop when detecting an oscillating AC voltage having a predetermined amplitude or more by receiving a differential signal between both ends of the force line CBf and the sense line CBs. Feedback loop condition for receiving oscillation detection signal 60s from detection circuit 60 and providing at least two types of loop condition switching means for a constant voltage feedback loop to control switching to another feedback loop condition different from the current feedback loop condition. A device power supply device for a semiconductor test device, comprising a changing means 20. According to the above invention, a device power supply device of a semiconductor test apparatus can be realized which can immediately suppress a dynamic oscillation phenomenon occurring in a DC voltage supplied by the device power supply device.

As one mode of the feedback loop condition changing means 20, there are provided loop phase condition switching means capable of switching to at least two types of loop phase conditions with respect to the constant voltage feedback loop, or continuously variable construction means. Further, there is provided a device power supply device for a semiconductor test apparatus as described above, which is a feedback loop condition changing means for switching and controlling to another loop phase condition different from the current phase condition.

As one mode of the feedback loop condition changing means 20, a gain bandwidth condition switching means capable of switching to a gain bandwidth condition of at least two types of loop gains with respect to a constant voltage feedback loop, or a continuously variable gain bandwidth condition. There is provided a device power supply device for a semiconductor test apparatus as described above, wherein the device power supply device is a feedback loop condition changing means for switching and controlling to a low bandwidth gain condition different from the current gain condition.

Further, as one mode of the feedback loop condition changing means 20, the device power supply of the semiconductor test apparatus is provided with both the loop phase condition switching means and the gain bandwidth condition switching means. There is a device.

As one mode of the feedback loop condition changing means 20, at least two kinds of bias current correcting means (for example, an output stage) for correcting non-linearity of the current buffer circuit in the output stage of the device power supply device during open loop. Means for changing the amount of idle current) or a feedback loop condition changing means for controlling the switching to another bias current condition different from the current bias current condition by providing a continuously variable component means. There is a device power supply device of a semiconductor test device.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings together with embodiments.

FIG. 2 is a block diagram showing the principle of the device power supply apparatus of FIG. 1; FIG. 2 is a time chart for explaining the operation of FIG. 1; FIG. This will be described below with reference to FIG. 6 and a characteristic diagram illustrating the non-linearity of the current buffer circuit. Elements corresponding to the conventional configuration are denoted by the same reference numerals.

The principle configuration of the main part of the device power supply device is as follows.
As shown in FIG. 1, a feedback loop condition changing means 20 is added to a conventional component.

The feedback loop condition changing means 20 includes a gain bandwidth condition switching means for changing at least two types of feedback loop conditions, and a loop phase condition switching means for switching between them. Then, when receiving the oscillation detection signal 60 s from the oscillation detection circuit 60, it switches to the other of the two types of feedback loop condition changing means, and holds this switching state. As a result, the feedback condition of the constant voltage feedback loop is changed to a different condition. As a result, the current oscillation state is immediately suppressed, the oscillation stops, and the state returns to the normal state.

As a specific example of the feedback loop condition changing means 20, as shown in FIG. 3B, a simple example of a loop phase characteristic, at least two types of loop phase conditions of a constant voltage feedback loop (FIG. 3F). And FIG. 3H), and includes a loop phase condition switching means for switching the loop phase condition. At this time, it is self-evident that the compensation conditions for the two types of loop phases are as follows in the case of a static load current.
Needless to say, both are designed under extremely stable feedback conditions. As this switching means, for example, a semiconductor switch or a reed relay can be applied. Then, as shown in the time chart of FIG. 2, the oscillation detection signal 60s obtained by the oscillation detection circuit 60 detecting the start of oscillation (see FIGS. 2C and 2F).
(See FIGS. 2D and 2G), by alternately switching to the other loop phase condition different from the current loop phase condition (A or B), the current loop phase condition (A or B) is controlled. The dynamic oscillation phenomenon is immediately suppressed and stopped (Fig. 2
E, H). As a result, there is obtained a great advantage that the device test can be continuously performed normally without any change. Here, as a specific example of the loop phase condition,
Generally, two types of phase compensation capacitors having different capacitance values, or a circuit in which the two types of phase compensation capacitors are individually connected in series with a desired resistor. As a result, the frequency point under the condition that the loop phase, which is the dynamic oscillation condition associated with the dynamic feedback loop of the load current, rotates by -180 ° moves. As a result, the dynamic feedback condition at the present time is different, and as a result, the dynamic oscillation phenomenon under the dynamic load current condition at the present time is suppressed and stopped.

Further, specific feedback loop condition changing means 2
As a second example of 0, as shown in FIG. 3A, there is a method including a gain bandwidth condition switching means for changing a loop gain in a frequency band equal to or lower than a feedback gain level (see FIG. 3E). That is, the feedback loop condition changing means includes a gain bandwidth condition switching means capable of switching to gain bandwidth conditions of at least two types of loop gains, and controls switching to a bandwidth gain condition different from the current gain condition. As a result, the dynamic oscillation phenomenon caused by the dynamic load current is changed to a different gain condition. As a result, the dynamic oscillation phenomenon at the present time is immediately suppressed and stopped. As shown in FIG. 6, some of the dynamic oscillation phenomena occur when a large current buffer B1 is not used due to an imbalance of a bias current of a current buffer circuit of a complementary configuration output stage at the time of a small load current. Depending on the linearity portion (see FIG. 6B), a dynamic oscillation phenomenon (dynamic oscillation phenomenon) rarely occurs in accordance with a dynamic follow-up operation of the load current. Also in this case, the dynamic oscillation phenomenon is suppressed by providing the feedback loop condition changing means described above. In this case, two types of bias current changing means for the current buffer B1 may be additionally provided as desired, and the bias current changing means may be switched and controlled.

According to the configuration of the present invention, when the oscillation detection signal 60s is received under two types of loop feedback conditions,
By adopting a configuration including a configuration means for alternately controlling switching to another loop feedback condition, a rarely occurring dynamic oscillation phenomenon can be instantaneously suppressed, and as a result, there is an advantage that a normal device test can be continuously performed. In addition, there is obtained an advantage that the device measurement quality can be maintained.

The means for realizing the present invention is not limited to the above embodiment. In other words, both the loop phase condition switching means and the gain bandwidth condition switching means may be provided, and each time the oscillation detection signal 60s is received, the switching may be performed sequentially or may be realized by a continuously variable configuration means. good.
The above-described loop phase condition switching means and the gain bandwidth condition switching means include two types of feedback conditions,
Although the description has been given of the specific example in which the switching is performed alternately, the configuration may be such that the switching is sequentially performed by providing three or more types of feedback conditions as desired.

As shown in FIG. 7, there is a device power supply device having a circuit configuration in which the guard line A3 shown in FIG. 1 is not provided and the shield line CBg is connected to the circuit ground GND1. It is clear that it is applicable.

The DUT terminals supplied by the device power supply device of the semiconductor test apparatus include a power supply terminal, an output terminal,
Both input terminals and input / output terminals are targets. Further, as the device power supply device, there is a device power supply device capable of responding to the case where the current direction to be supplied to the DUT terminal is either a sink current or a source current. In this case, the same applies as described above.

[0031]

According to the present invention, the following effects can be obtained from the above description. According to the configuration of the present invention described above, a plurality of loop feedback conditions are provided, and when the oscillation detection signal 60s is received, a configuration is provided that switches to another loop feedback condition to control the occurrence of the oscillation detection signal. As a result, the dynamic oscillation phenomenon can be instantaneously suppressed, so that a normal device test can be performed continuously without interruption. That is, a great advantage that the necessity of retesting the test item is eliminated is obtained. Further, there is obtained an advantage that the quality of device measurement can be maintained. Therefore, the technical effect of the present invention is great, and the industrial economic effect is also great.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of a main part of a device power supply device according to the present invention.

FIG. 2 is a time chart for explaining the operation of FIG. 1;

FIG. 3 is a diagram illustrating a Bode diagram having two gain bandwidth characteristics (slew rate characteristics) for explaining the function of a feedback loop condition changing unit, and a Bode diagram having two points of phase compensation characteristics. FIG.

FIG. 4 is a diagram illustrating the configuration of a principal part of a conventional device power supply device.

FIG. 5 shows a conventional waveform example of a dynamic oscillation phenomenon at an output terminal of a device power supply device and an alarm signal (ALAR).
8 is a timing chart illustrating detection of M).

FIG. 6 is a characteristic diagram illustrating a non-linearity portion associated with an imbalance of a bias current of a current buffer circuit.

FIG. 7 is a diagram illustrating another principle configuration of the device power supply device according to the present invention.

[Explanation of symbols]

 A1 inverting amplifier B1 current buffer C1 bypass capacitor R1 resistor A2 sense amplifier R2 feedback resistor A3 guard amplifier R3 series resistor 20 feedback loop condition changing means 30 DA converter 50 device power supply device 60 oscillation detection circuit 70 load current measurement unit CB station Cable DUT Device under test

Claims (5)

[Claims] 1. A DUT terminal of a device under test (DUT) is a power supply terminal, an output terminal, an input terminal, or an input / output terminal, and includes at least a force line and a sense line between the DUT terminal and the device power supply device. Connected, the force line is a line for supplying a load current of a power supply current or a sink / source current flowing to the DUT terminal, the sense line is a line for detecting (sense) a voltage signal of the DUT terminal, In a device power supply device of a semiconductor test device forming a constant voltage feedback loop for controlling a voltage of the DUT terminal by a sense line to be constant, an inverting amplifier, a current buffer, the force line, the sense line, a sense amplifier, a feedback resistor, To form a constant voltage feedback loop, and receive a differential signal between both ends of the force point and the sense point to oscillate with a predetermined amplitude or more. An oscillation detection circuit for detecting the start of oscillation of the constant voltage feedback loop when the AC voltage is detected, and at least two types of loop condition switching means for the constant voltage feedback loop in response to an oscillation detection signal from the oscillation detection circuit. And a feedback loop condition changing means for controlling switching to another feedback loop condition different from the current feedback loop condition, the device power supply device for a semiconductor test apparatus. 2. A feedback loop condition changing means comprising: a loop phase condition switching means capable of switching to at least two types of loop phase conditions with respect to a constant voltage feedback loop; 2. The device power supply device of a semiconductor test apparatus according to claim 1, wherein the device is a feedback loop condition changing unit that controls to switch to another loop phase condition different from the condition. 3. The feedback loop condition changing means includes a gain bandwidth condition switching means capable of switching to a gain bandwidth condition of at least two types of loop gains with respect to a constant voltage feedback loop, or a continuously variable configuration means. 2. The device power supply device for a semiconductor test apparatus according to claim 1, wherein the device is a feedback loop condition changing means for controlling to switch to a low bandwidth gain condition different from a current gain condition. 4. The feedback loop condition changing means includes both the loop phase condition switching means according to claim 2 and the gain bandwidth condition switching means according to claim 3. Device power supply for semiconductor test equipment. 5. The feedback loop condition changing means includes at least two kinds of bias current correcting means for correcting non-linearity of the current buffer circuit at the output stage of the device power supply device at the time of open loop, or continuously variable constituent means. 2. The device power supply device for a semiconductor test apparatus according to claim 1, further comprising feedback loop condition changing means for switching and controlling a bias current condition different from a current bias current condition.