JP2585007B2 - Electrical component measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention applies a bias voltage (or current),
The present invention relates to an electric component measuring device for measuring characteristics of electric components at high speed.

[Conventional technology and its problems]

Measurement is often performed by sequentially setting a signal source and a measurement unit, such as applying a DC bias to an electric component to measure an AC impedance.

As an example of them, a measurement of a voltage variable capacitance diode (hereinafter referred to as a varicap) will be described as an example, but the same concept is applied to a device having a larger number of signal sources and measurement points.

Find the capacitance of the varicap as a function of applied voltage C
The basic operation of the −V characteristic measurement was as follows. (I)
DC bias value setting, (B) DC bias voltage setting, (C) Capacity measurement range setting, (D) Bridge section balance, (E) Bridge section output analog / digital conversion, (F) Digital value , And the resulting measured value output is sequentially repeated. Since each of these processes is executed in series, the time required for measuring the capacitance value for one DC bias is the sum of the time required for each of the processes (a) to (f).

However, in recent years, the measurement system has been controlled by a microprocessor, and with the improvement of its performance, multitasking and parallel control functions have come to be used. By processing, the measurement time can be shortened.

For example, in the measurement system described in detail in Application Note 321 “4277ALCZ Meter Option H03 / H04 Application to Varicap Diode High-speed Sorting” issued by Yokogawa-Hewlett-Packard Co., Ltd., as shown in FIG. The processes (a), (b), and (d) are performed in parallel within the processing time of (f). The example of FIG. 4 is effective in a multi-point measurement in which the DC bias is sequentially swept and the capacitance value of the varicap corresponding thereto is measured.

In the above conventional example, since the processing of (c) is not performed in parallel, if it is necessary to switch the measurement capacity range, it is necessary to start over from the processing of (c) after changing the capacity range.

Therefore, when it is necessary to perform high-speed measurement, the user selects a measurement range according to the maximum capacity during the DC bias sweep so that the range is not switched during a series of multi-point measurements.

In this case, when the capacitance of the varicap is small (that is, when the applied reverse voltage is large), the measurement accuracy of the capacitance is degraded.

[Object of the invention]

Accordingly, it is an object of the present invention to provide an electric component measuring apparatus with less deterioration in accuracy even at high speed measurement.

(Example of the invention)

In one embodiment of the present invention, the measurement device is a typical microprocessor controller, and the settings of the signal source and the measurement unit are:
This is performed by inputting data corresponding to registers attached to them. The configuration of the measuring device is based on the same principle as the measuring device HP4278A or HP4277A commercially available from Yokogawa Hewlett-Packard Co., Ltd. I do.

In the present invention, the fact that the characteristics of the measured varicap can be predicted in advance is effectively used. When measuring a large number of varicaps of the same specification continuously, as in the measurement performed on a varicap production line, etc., setting the measurement range within a certain tolerance from the DC bias will improve the accuracy. High measurement can be performed.

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a timing chart of the embodiment of FIG. In FIG.
The varicap 1 to be measured is energized by a DC bias source 3 via an AC power supply 2 for measurement and an AC blocking device 4, and a bridge circuit 5 applies an AC voltage applied to the varicap 1,
Generates an output corresponding to the current. The output is converted to a digital value by an A / D converter (analog / digital converter) 6.

The digital value is processed by the arithmetic unit 7 to obtain a capacitance value.

These devices are controlled by a microprocessor 10 and a memory 11 via a bus 12. Further, an external digital signal is input via the interface 13.

As is apparent from FIG. 2, the measurement range setting is also performed in parallel with the DC bias setting during the digital calculation and output processing of the previous measurement. N and N + 1 in the figure indicate that the measurement belongs to the N-th measurement and the N + 1-th measurement. The measurement lens setting and the DC bias setting performed in parallel in time in this way are intended to perform the bridge equilibrium with these settings within a time equivalent to the digital processing time. Therefore, it is not essential that these processes be simultaneously performed in time or overlap.

FIG. 3 shows an example of the characteristics of the varicap and the measurement range. For the measurement, change the DC bias voltage to 0V, 1V, 2V, 4V, 6V, 10V, and change the measurement range accordingly to 512pF, 512pF, 128pF,
Perform by setting to 32pF, 32pF, 8pF. Data for setting the measurement range corresponding to the DC bias voltage is stored in a table format in a memory accessed by a microprocessor that controls the apparatus according to the embodiment of the present invention. These setting contents can be rewritten by a known method via the keyboard of the apparatus or an external communication function.

When this device is used via a communication function (for example, using a GP-IB bus), the measurement point is automatically selected by specifying the type of the varicap to be measured, and the DC bias and the measurement range Can be easily set and used automatically.

〔The invention's effect〕

As is clear from the above embodiment, the predetermined range is set together with the DC bias, and particularly when performing continuous multipoint measurement, the range is set during the digital calculation of the previous measurement. Is shortened, and the deterioration of accuracy is small. Therefore, it is convenient for practical use.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a timing chart of the embodiment, and FIG. 3 is a diagram showing an example of characteristics of a varicap and a measurement range. FIG. 4 is a measurement timing chart of the prior art.

Claims (2)

(57) [Claims] 1. A measuring apparatus for measuring the AC impedance of an electric component to be measured, which varies in accordance with a DC bias, at multiple points under microprocessor control, and data for setting a plurality of DC biases and a measurement corresponding to the DC bias. Data for setting a range is stored in a memory, and a microprocessor reads out the data from the memory to automatically set a DC bias and a measurement range. . 2. The device according to claim 1, wherein the electric component to be measured is a varicap, the DC bias is a voltage applied to the varicap, and the measurement range is a capacitance range. Electric component measuring device.