JPH03214079A - Measuring apparatus for input threshold of ic - Google Patents

Abstract

PURPOSE:To enable measurement of an output state of a terminal without being examined with a higher measuring accuracy by applying an analog sweep voltage dropping gradually after a gradual rise to an input terminal of an IC to monitor a current flowing through a power source terminal of the IC. CONSTITUTION:As a sweep voltage generation circuit 1 generates analog sweep voltage waveform S with a passage of time, an input voltage VIN of a DUT 6 rises linearly. When the input voltage exceeds an input threshold voltage of an input circuit of the DUT6, an internal circuit receiving the input operates. At this point, current flows transiently and appears as a characteristic graph P of a current IDD. This static consumption current IDD is monitored with a peak current detection circuit 8 and when this exceeds a comparison reference current level ITH, it means that this surpasses an input threshold. So, a peak detection signal D is generated at time T1 from the circuit 8 and the circuit 1 receiving the signal stops sweeping. The current voltage value is measured with a voltage value measuring circuit 7 through a switching circuit 5. This is taken into a measurement control circuit 10 receiving the signal D as results of measurement.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an input threshold measurement device for an IC. The present invention relates to a large power threshold measuring device capable of improving measurement accuracy for large Kaslenjord voltages as input signal levels.

[Prior Art] As a conventional large-power threshold measurement method, for example, a pulse with a voltage higher than the threshold voltage L1 is applied to the input of an IC, and the voltage is gradually changed at a predetermined period so as to approach the threshold voltage. When a pulse of a predetermined level is generated on the output side of the IC, the voltage of the pulse at the input terminal is 1.
One value is measured as the threshold voltage. In this case, the generation of a pulse on the output side is achieved by detecting the point at which the output side changes from HIGH level (hereinafter referred to as "H") to LOW level (hereinafter referred to as "H") or from &lL" to "H". It will be done.

Note that such detection of the output side state is normally performed by so-called binary search, in which a strobe pulse is generated at a predetermined period and the output state is obtained as a digital value. will be detected.

[Problem to be Solved] In this type of device, since the voltage applied to the input terminal is determined in stages, the threshold voltage of the voltage value between the stages cannot be measured.

Therefore, the measurement accuracy is determined by the number of steps, and since it is relatively rough, there is a drawback that the product yield is low.

In this case, in order to improve the measurement accuracy, it is sufficient to take the steps of the electric current j1 applied to the input side in small steps, but if the steps are taken in small steps, the time during which the (It takes 71tll time to adjust.

Also, the output side changes from “H” to “L” or from “L” to “
Detection of the state of change to "H" is performed in accordance with the output terminal r determined by the relationship between the predetermined input and output.The more the output fAJ' is, the more time it takes to measure.
/l1lllDepending on the target IC, do you need to understand the timing relationship between input and output? I11 must be determined, and timing-related settings must also be made.

Moreover, the output side changes from “H” to 14L,
What changes from "'L" to "H" is determined according to the output terminal r pin, so examine the internal circuit for each product type (model) and determine which one it is for each output bin. It is also necessary to measure after deciding.

This invention solves the problems of the prior art, and improves the accuracy of large force threshold measurement by 1.
Another object of the present invention is to provide a large-power threshold measuring device for an IC that can measure the threshold without investigating the output level of the terminal r.

[F stage for solving the problem] The configuration of this invention to achieve the above 11 objectives is as follows:
A sweep voltage generation circuit generates an analog sweep voltage that gradually drops to 1-gIf over time and then gradually drops, and supplies it to the input terminal r of the IC, and the current flowing to the power supply terminal r of the IC is The device is equipped with a detection circuit for detecting that the level has been exceeded, and a voltage measurement circuit for determining the sweep voltage of the sweep voltage generation circuit at that point in time in accordance with the detection signal of the detection circuit.

[Operation] In this way, an analog sweep voltage of 15r, L and then gradually decreasing is applied to the input terminal r of the IC, and I
Since the current flowing to the power supply terminal of C is monitored, it is possible to detect whether or not the internal circuit has operated through this monitoring, and the sweep voltage at the time of detection is the threshold voltage at the input in terms of whether the internal circuit has operated. You can see it.

In such a measurement method, the sweep voltage at the input terminal is an analog value of 1-S? , since it descends/l
Since the operating state is detected by monitoring the current flowing through the power supply terminal, it is possible to understand the timing relationship between input and output, and to investigate and study the output status of each output terminal. It is no longer necessary, and the human output relationship at any end r can be measured under the same measurement conditions.
Large shear shield measurements can be performed efficiently.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a large-scale IC leakage hold measuring device to which the present invention is applied, and FIG. 2 is an explanatory diagram of its operation in a measuring state.

In FIG. 1, 1 is a sweep voltage generation circuit,
ROM2 and 1]/A conversion circuit (f)/A)3, and R
It consists of a control circuit 4, etc. that accesses the OM2, and as shown in FIG.
, L, a chevron-shaped analog sweep voltage waveform S having a ramp voltage characteristic that gradually decreases (gradually decreases, then gradually decreases) is generated at a predetermined speed over time.

In the ROM 2, values corresponding to each time of the digital data before conversion to generate the analog sweep voltage waveform S are sequentially stored in correspondence with each address. The side control circuit 4 is
Consists of a clock generation circuit, program counter, etc.
By generating an address to access ROM2, accessing ROM2 using that address, and sequentially incrementing the access address value in accordance with the clock, analog conversion rTil is performed sequentially over time from each address in the time unit of the clock period. Read the digital data value of 1) and apply it to the A conversion circuit 3. As a result, an analog sweep voltage waveform S that changes over time is output from the 1)/A conversion circuit 3. Further, when the control circuit 4 receives a sweep stop 1 signal from a peak current detection circuit 8, which will be described later, it starts incrementing the address counter using the clock received from the clock generation circuit. As a result, the address of ROM2 continues to be accessed in accordance with the clock at the address of the stopped position, and the digital data at that position is
l1) The analog voltage 1 [value continues to be sent to the conversion circuit 3 and continues to be output from the sweep voltage generation circuit l at the time when the sweep stop signal is received. The signal 1) and output of the sweep voltage generating circuit 1 are transmitted via the switch circuit 5 to one of the input terminals r of the IC(1,)UT) 6 to be measured.
It is input to N.

The switch circuit 5 is a changeover switch. When the switch t'<'J is received from the peak current detection circuit 8, the output of the sweep voltage generation circuit 1 is switched to be inputted to the voltage value 11111 constant circuit 7 side.

1) U T 8 is a circuit, such as CMO 8 or ASIC, in which an inverter or the like constituting a large cover sofa is connected to the input terminal f' (IN). There is a threshold voltage for the operation that operates in response to immersion. VDD is
1) A power supply terminal r of the UT8, and I) the UT6 receives power at a voltage value +VDD from the power supply circuit 8 via the peak current detection circuit 8 at this terminal r.

The peak current detection circuit 8 is a current level detection circuit consisting of a so-called comparison circuit, and is connected to the power supply circuit 9 by I) U.
Static current consumption flowing into the power supply terminal J'VDD of T8■
When DD exceeds a predetermined comparison target level ITH (see Figure 2), a detection signal is generated and the sweep is stopped].
Send 1 to the power supply circuit 1 as Sive power 11.
-1 It is also applied to the switch circuit 5 as a switching signal. Furthermore, it is sent to the Atl+constant control circuit IO as peak detection (, :).

The Al11 constant control circuit 10 is a control circuit for the entire device that starts the sweep voltage generation circuit 1 and converts the measured voltage value obtained from the voltage value measurement circuit 7 to 1. It is equipped with a processor, memory, and personnel equipment that displays measurement results.

When the peak detection circuit 8 receives the peak detection signal 5] from the peak current detection circuit 8, the resulting voltage value is collected from the seven juice value measurement circuit 7 at a subsequent predetermined timing.

Next, the overall operation of the large shear shield measuring device having such a configuration will be explained with reference to FIG.

First, in response to the operator's operation to start the
-1 constant control circuit 10 sends a starting signal to sweep voltage generation circuit 1, and sweep voltage generation circuit 1 generates analog sweep voltage 11 waveform S shown in FIG. 2 over time. Accordingly, l) The input terminal VIN of the U T 6 (the voltage value input to the input terminal J'-IN at a certain time of the analog sweep voltage waveform S in Fig. 2) is sequentially and linearly changed to 1., hlL. ,,To go. When it reaches a certain voltage value and exceeds the large Kathlengord voltage of the input circuit of I) tJ T 6, the internal circuit that can pass the input of 42 operates. At this time, depending on the operation of the internal circuit, a current flows transiently as an operating current in the IC such as the CMO 5, and this appears as a characteristic graph P of the current IDD having a peak as shown in FIG.

This static 11-current consumption value IDC is calculated by the peak current detection circuit 8.
static 11 current consumption (+1' [When IDD exceeds its comparison base current level ITH, I) [JT
This corresponds to when the inverter and the like constituting the input Banoff r and the like inside 6 perform an inverting operation. And this gives you a taste of what it is like to be beyond the ordinary. Therefore, at this time, a peak detection signal is generated from the peak current detection circuit 8 at time TI. It's a stop at Ichishin Gino.
When the sweep electric circuit 11 is turned off, the voltage value at that time is measured by the electric IF value measuring circuit 7 via the switch circuit 5. this is,
Detection Ihashi month) received 7! $1 It is taken into constant control amount control 0 as a measurement result.

At this point, the measurement control circuit 1O performs control to cancel the clock stop 1-1 signal S) to the sweep voltage generation circuit 1.

-) is sent. As a result, the sweep voltage generating circuit l starts the sweep with s+Il:, and the sweep voltage becomes
As shown in FIG. 2, the lamp voltage will eventually become established, and then the lamp voltage will drop. In this step-down process, when the sweep voltage drops below the input threshold voltage, the voltage increases by s +1, and the inverter, etc. related to the input that receives this voltage performs an inverting operation, and at this time as well, the static IL consumption current increases by 10
0 flows. As a result, even at this point, the peak detection signal 5] is issued from the peak current detection circuit 8 at time t1.
As a result, the sweep voltage generation circuit 1 stops the sweep, the voltage value at that time is measured by the voltage value measuring circuit 7, and it is sent to the measurement control circuit 10 as 7111.
captured as a fixed result.

At this point, the measurement control circuit IO stores the obtained measurement values in Table 1.
1 (Display the measurement result on the device and stop the operation of the sweep voltage generating circuit l).

It should be noted that the current level ITH, which is the comparison base of the peak current value detection circuit 8, can be adjusted from the outside, and 1) U T
Selected according to the characteristics of 8.

By doing as follows, the input threshold voltage can be obtained. In this case, since the voltage value applied to the input of I) U T 8 is an analog voltage value, the input threshold voltage is the sweep voltage generating circuit l. It is possible to measure the voltage accuracy generated by the voltage rather than stepwise. Moreover, in this case, since the binary search for detecting the output state according to the strobe pulse is not used, it is not affected by the measurement period of the strobe pulse. Therefore, stable measurement can be performed in a short time with high measurement accuracy. Note that the accuracy of the analog value of the sweep voltage can be determined by the data stored in the ROM 2 and the accuracy of the 1)/A conversion circuit 3.

As explained above, in this embodiment, the ROM and 1
)/A converter circuit is used to generate an analog voltage II: in a sweep voltage generation circuit, but this circuit is not limited to such an example (lamp voltage generation using a capacitor etc. The analog voltage may be directly generated by a circuit.

In addition, in the embodiment, the sweep of the sweep voltage generator is stopped when a peak of the static current is detected, but the output voltage of the sweep voltage generator at that time is adjusted according to the peak detection signal. If you obtain the value by sample-holding, it is not necessary to stop the sweep.
You don't have to let it happen.

[Effects of the Invention] As can be understood from the following explanation, in this invention, since the sweep voltage at the input terminal drops by 1t in analog value, the measurement accuracy can be improved. Since the operating state is detected by monitoring the current flowing through the power supply terminal R, it becomes very difficult to grasp the timing relationship between input and output, and investigate and study the output status of each output terminal R. Since the human output relationship can be measured under the same measurement conditions, input threshold measurements can be performed efficiently.

4. fm 'l'-Explanation of the Drawings Fig. 1 is a block diagram of an IC large force threshold value measuring device to which the present invention is applied, and Fig. 2 is an explanatory diagram of its operation in a steady state. .

l...Sweep voltage generation circuit, 2...ROM.

3...I)/A conversion circuit, 4...control circuit, 5
...I C (1) UT), 8... switch circuit,
7... Voltage value measurement circuit, 8... Peak current detection circuit, 9... Power supply circuit, lO... Measurement control circuit.

Claims (1)

[Claims] (1) I having a circuit with threshold characteristics on the input side
A measurement device that measures the input threshold voltage of the IC generates an analog sweep voltage that gradually increases over time and then gradually decreases over time.
a sweep voltage generating circuit that supplies the input terminal of the I
a detection circuit that detects that the current flowing through the power supply terminal of C exceeds a predetermined level; and a voltage measurement circuit that measures the sweep voltage of the sweep voltage generation circuit at that time in response to a detection signal of the detection circuit. An input threshold measurement device for an IC, comprising: