JPH01131468A - Current loading and voltage driver circuit - Google Patents

Abstract

PURPOSE:To reduce the size of the title circuit and to increase its density by providing a means for current loading and a means for applying a prescribed voltage to a circuit element to be measured, and switching said means by a switching means. CONSTITUTION:The circuit includes a programmable current source 21, two power sources of a current sink 22, and two diode bridge circuits B21 and B22, and is equipped with the switching means for realizing a current loading function and a voltage driver function. In a current loading mode, only transistors (TR) Q21 and Q24 are turned on to load a positive and a negative current to a circuit terminal to be measured from the current source 21 and current sink 22 through a load R. In voltage driver mode, on the other hand, only the TRs Q21 and Q24 are turned on so as to set the current source 21 and current sink 22 to max. values and output a low-reference voltage LRef as an output voltage and only TRs Q23 and Q24 are turned on so as to obtain a high-reference voltage HRef as the output voltage.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a method for evaluating the voltage and current DC characteristics of each terminal of a circuit element under test in integrated circuit measurement. The present invention relates to a current load/voltage driver circuit that supplies measurement waveforms and the like to a circuit element to be measured and loads a current and the like to the circuit element to be measured.

[Prior art and its problems]

For example, when measuring DC characteristics of integrated circuits, depending on the terminal specifications of the circuit element under test, voltage application/current measurement (mainly input terminals) or current application/voltage measurement (mainly output terminals)
will be held. Conventionally, a test head section to which terminals of a circuit element to be measured are connected is mainly provided with a unit consisting of a comparator C4, a current loader 4, and a voltage driver D4 for each terminal, as shown in FIG. In actual measurement, when taking out a current from the output terminal of a circuit element to be measured, a current load circuit 4 is connected, and comparison and discrimination are performed with a given threshold value by a comparator C4. On the other hand, when supplying a predetermined voltage to the input terminal of the circuit element under test, the voltage driver D4 is connected and the comparator C4 makes a determination.

In recent years, there has been an increasing demand for smaller test head sections, and as a result, it is necessary to increase the density of the units provided at each terminal. Furthermore, current load 4 and voltage driver D
4 are used in different measurement situations, and therefore, because they coexist, power is wasted when not in use.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned conventional problems, reduce the number of units in the test head section, and provide a current load/voltage driver circuit that is integrated into a high-density hybrid circuit.

[Summary of the invention]

In one embodiment of the present invention, as shown in FIG. 1, in order to evaluate integrated circuits, a voltage driver applies a desired voltage waveform to each terminal, and a current load function loads a desired current to each terminal. This is a current load/voltage driver circuit consisting of switching means for switching these.

[Embodiments of the invention]

FIG. 2 shows a current load/voltage driver circuit according to a preferred embodiment of the present invention. First, in order to make the explanation of this embodiment easier to understand, a conventional current load will be briefly explained. In FIG. 5, the normal current load L5 is mainly the current source 51.
It is composed of a bridge circuit formed from a current sink 52 and four diodes OS+ to DS4. These two positive and negative power supplies are programmable and can be set to arbitrary values. This depends on the output voltage value to be measured.
By setting an arbitrary threshold voltage Va, it is possible to switch to current application (current source 51) or current extraction (current sink 52). In this embodiment, there are two proramaple power supplies, a current source 21, a current sink 22, and a diode bridge circuit BZ of 2&Il.
l+ szg, and is provided with switching means for realizing current load function and voltage driver function.

In current load mode, transistor Q21 +
4 is turned on, and the voltage L□ becomes the threshold voltage Va in FIG. As described above, the current source 21 is connected to the circuit element under test (not shown) via the load resistor R.
and loading a positive or negative current from the current sink 22. In the voltage driver mode, the current source 21
When setting the current sink 22 to its maximum value and setting the output voltage of this circuit to the low reference voltage L□, the transistor low! When only Q24 is turned on and the output voltage is set to the high reference voltage H&#, the transistors QtM, QZ &
Switch it so that only the switch is turned ON. In addition, by turning on only the transistors Qtt and (hs) so that no current flows through either diode bridge circuit B!l+Lz, a high impedance mode can be set at the output. The 0N10FF operation of these transistors UZ+ to [1zh is a well-known technique, and its explanation is omitted here, and it is not particularly limited. In this embodiment, a transistor is used as a switching means, but for example, a FET, etc. It is also possible to use other switching elements.

Note that the resistor P connected to the output is used as an output matching resistor of the voltage driver. Furthermore, in high-speed circuits, if the output voltage is zero, it can be used as the termination of an external circuit.

FIG. 3 shows the pin electronics of an integrated circuit measuring device, and a method for identifying circuit elements to be measured will be described below as an example of application. In pin electronics, the current load/voltage driver circuit D/L of the present invention is used not only as a DC current source or voltage source but also as a pulse driver exceeding 100 MHz. In the following description, for the sake of simplicity, a case will be shown in which the current source is operated with the current source closed.

Pin P ff++ P:l! +, ++ P:lk l+
+j P'Jn is connected to each lead of a circuit element under test (not shown) and is used to drive each lead and measure the signal on each lead. Pin electronics PIEi+, PE: +z, , PEz
m1. , IPeffa, and have substantially the same configuration. The pin electronics PH31 will be explained in detail below.

The pin electronics Pth + operates under the control of an external controller (not shown). Switch S, l connects pin P31 to either 5ztn or Sz+b.

Switch 5: +1 and current load/voltage driver circuit D/
The connection of L+ can also be made as shown in FIG. In that case, disconnect the input of voltage comparator C3r at point
Just connect it to H, pins P and l are 531m
When connected to the current source D/L, the bin P31 is energized. The voltage of bin P31 is compared with two different threshold values by a voltage comparator Cal, and the magnitude relationship (indicated by the HT and LT times signals) with respect to each threshold value is pre-amplified by the strobe signal SI from an external controller.
Latched to prop FF. The latched signals HT+' and LT,' corresponding to HT, and LT, respectively, are input to the comparison logic CLI and determine whether they are higher than the high level threshold, lower than the low level threshold, or both thresholds. Depending on the open level, the outputs H1, Ll, and Wl each become high level. Multiplexer MUX is output meter, Ll, Wl
is input, and a pass/fail signal (referred to as a pp multiplied signal) is output to the wired OR circuit PF according to a predetermined criterion. On the other hand, the output meter, L1. The contents of Wl are latched into the status register SR and read out from the output SRO, onto the data bus DB.

If the pin electronics connects pin P31 to 531k, the output voltage of programmable voltage source v1 is applied to pin Pffl, and the current value flowing into bin Pffl is compared with two thresholds by current comparator C:l□. . Comparison output processing and wired OR circuit PF
, and the data output to the status register output SRO is similar to the output of the voltage comparator Cal described above, HTz, LT
z, FF, HTz', LTz', CLz, H2, W2.
L2゜M (IX, Si2 is HT+, LT+, FP, HT
This is achieved by performing the operations of +', LT+., CL+, HIJI, Ll, and SP, respectively.

Pin Electronics PE51. PH3z9. ,,P.E.
3* , , , PH37 is divided into several groups, the wired-OR circuits of each group are all connected, and one input of the pass/fail register PFR is notified of the presence or absence of a fail output in the corresponding group. .

Is the external controller a register PFI? inspect the contents of
Once a failing group is found, it serially polls the pin electronics in that group and reads the contents of each status register. In this way, the external controller is notified of the state of the pin electronics that gave the fail output.

In this embodiment, the measurement of a packaged integrated circuit has been described in detail, but the present invention can also be implemented in the evaluation of each terminal of an integrated circuit in a wafer state, for example.

〔Effect of the invention〕

As explained above, the current load/voltage driver circuit according to the present invention is made smaller and consumes less power by combining conventional different length nift elements.
Therefore, it greatly contributes to cost reduction.

Furthermore, this circuit improves the accuracy of integrated circuit measurements by reducing the parasitic capacitance that occurs in the relay connected to the comparator.

Furthermore, miniaturization allows for a highly flexible configuration of pin electronics.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a current load/voltage driver circuit according to an embodiment of the present invention. FIG. 2 is a circuit diagram of a current load/voltage driver circuit according to an embodiment of the present invention. FIG. 3 is a configuration diagram of pin electronics using the current load/voltage driver circuit of the present invention. FIG. 4 is a diagram showing a unit configuration of a conventional current load and voltage driver. Figure 5 is a circuit diagram of a conventional current load. C++C4: Comparator, L: Current load. D4: Current driver, 21.51: Current source. 22.52: Current sink. PH3+, PH3g+,,,PEzz,,,+PE1
t+, , PE: tn: Pin electronics.

Claims (1)

[Claims] In measuring the characteristics of a circuit element having a plurality of terminals, means for loading a current to the circuit element under test through each of the terminals, and means for applying a predetermined voltage to the circuit element under test through each of the terminals. A current load/voltage driver circuit comprising switching means for switching between the current load and the voltage application means.