KR890004530Y1 - Circuit of electric current gain of transistor - Google Patents

Abstract

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Description

Current Gain Ratio Measurement Circuit of Transistor

1 is a circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

1: CPU 2: Memory

3: decoder 4: switching drive circuit

5: printed circuit board 6: current gain detection unit

7: current gain level adjusting unit 8: differential amplifier

9: Analog / Digital Converter OP ₁ -OP ₄ -OP: Amplifier

ZD: Zener Diode SW: Switching Circuit

The present invention relates to an electronic circuit for measuring the current gain rate of a transistor inserted on a printed circuit board (PCB).

In general, in order to check whether the printed circuit board to which the part is inserted performs a predetermined function, the value of the inserted part on the printed circuit board is inserted at the designed rated value and inspected whether it is operating within the range of the design specification. It is necessary to assemble, but it can exclude defective products. However, the conventional PCB raster which measures the rating of the component inserted on the printed circuit board can only measure the rated value of the passive element such as resistance, coil, capacitor, etc., but also the rated value of transistor such as the active element (eg gain ratio). Since it is impossible to measure the defects in the components inserted on the printed circuit board when the transistors are inferior to the ratings, the product defects are caused by the defects of the transistors.

The present invention has been made in view of the above situation, and provides a current gain ratio measuring circuit of a transistor which measures a current gain ratio of a transistor inserted on a printed circuit board so as to exclude a product defect caused by a defective transistor. The purpose is to.

Hereinafter, the configuration, operation, and effects of the present invention will be described in detail with reference to the accompanying drawings.

The present invention provides a Zener diode (ZD) in a PCB tester having a central processing unit (1), a storage unit (2), a decoder (3), and a switching drive circuit (4) to measure a printed circuit board (5). And a current gain detector configured to include an OP amplifier OP ₁ and resistors R ₁ -R ₅ to detect current gain with a base current Ib of the transistor Q ₁ inserted into the printed circuit board 5. 6) and an OP amplifier OP ₂ (OP ₃ ), resistors R ₆ -R ₁₀ , and a switching circuit SW to adjust the current gain to adjust the level of the signal detected by the current gain detector 6. Level amplification section 7, OP amplifier OP ₄ and resistors R _11- R ₁₃ and variable resistors VR ₁ for differential amplification of differentially regulated storage gain (8) and differential amplification The analog / digital converter 9 which converts the output signal of the section 8 into a digital signal and supplies it to the storage device 2 is configured.

Reference numeral SW ₁ is a power switch, S ₁ -S ₃ is a switch in the switching circuit (SW), IC is a collector current of the transistor under test.

FIG. 1 shows the specific circuit defect of the present invention having the above structure. In order to measure the rated value and the like of the printed circuit board 5 having the component inserted therein, the storage device is controlled by the central processing unit 1. Data is output from (2) to connect each side terminal of the PCB tester to the printed circuit board 5 through the decoder 3 and the switching driver circuit 4, respectively. Accordingly, the signal input through each measuring terminal of the PCB tester is analyzed by the central processing unit 1 to determine whether the component is rated or incorrectly inserted.

In this case, when the current gain ratio of the transistor Q ₁ , which is an active element inserted into the printed circuit board 5, is to be measured, the central processing unit 1 uses the decoder 3 and the switching driving circuit 4 to print the printed circuit. The collector, the base, and the emitter of the transistor Q ₁ inserted into the substrate 5 are connected to each measurement terminal of the PCB tester, thereby binding them as illustrated.

Then, the current gain detector 6 has a closed circuit including the transistor Q _{1. When} the power switch SW ₁ is turned on to measure the current gain ratio, the power supply Vcc is supplied to the circuit, which is a zener diode ZD. The potential is set by the power supply to the resistors R ₂ -4 and OP amplifiers OP ₁ , respectively. The OP amplifier inverting input terminal of the (OP ₁₎ (-), the resistance (R ₂₎ (R ₃₎ and the constant voltage is supplied by the partial pressure of, OP amp resistance to the output of the (OP ₁₎ (R ₅₎ and transistor ( As it is configured to be fed back through Q ₁ ) to be supplied to the non-inverting terminal (+), the non-inverting terminal (+) of the OP amplifier (OP ₁ ) has the same potential as the inverting terminal (-) due to the characteristics of the OP amplifier. .

Therefore, the potential applied to the resistor R ₄ becomes constant, and accordingly, the collet current Ic becomes constant.

In general, the current gain is the gain of the collector current over the base current of the transistor. If the current gain is β, the base current is IB, and the collector current is Ic,

β =

When the current gain β is constant, the base current and the collector current are proportional to each other. Therefore, if the collator current Ic is kept constant, the current gain rate can be measured by measuring the base current Ib.

In the present invention, the collector current Ic of the transistor Q ₁ is kept constant through the OP amplifier OP ₁ and the resistor R ₄ , and then the change in the base current Ib is applied to the potential difference through the resistor R ₅ . Detection. In other words, the potential difference across the resistor (R ₅ )

V ( ₃₅ ) = R ₂ × Ib

= R ₅ ×

The collector current Ic is multiplied by the value of the resistor R ₅ and divided by the current gain β.

The signal detected in this way is level-controlled by the current gain level adjusting unit 7, which amplifies respective detection signals in the OP amplifiers OP ₂ and OP ₃ , and in the central processing unit 1 switches the switching circuit 4. When one of the switches of the switching circuit SW is connected through, for example, when the switch S ₁ is connected, the current gain detection unit 6 is connected to both ends of the resistors R ₆ , R ₈ , and R ₇ connected in series. Detection signal is amplified and level adjusted and output to the differential amplifier 8.

The automatic amplifier 8 amplifies by the potential difference across the resistor R ₅ and supplies the detection signal to the analog / digital converter 9.

Accordingly, since the current gain detected by the current gain detection unit 6 becomes a digital signal, the central processing unit 1 calculates the current gain rate of the transistor Q ₁ and then determines whether it meets the design specification.

When the signal detected by the current gain detection unit 6 is very large or small, the level may be adjusted by changing the switch rod SW point of the level adjusting unit 7.

In this way, when it is determined that the component is specified in the central processing unit 1, a signal is supplied to the decoder 3 and the switching drive circuit 4 to measure another transistor to change the connection point of the measurement terminal of the PCB tester.

In this process, when the gain ratio of the transistor is not a prescribed value, it is notified to the outside to remove the defects, thereby improving the productivity and quality of the product.

As described above, the present invention measures the current gain of the transistor inserted on the printed circuit board to know whether the rated transistor is inserted, thereby improving the productivity and quality of the product.

Claims (1)

In a PCB tester having a central processing unit (1), a storage unit (2), a decoder (3), and a switching drive circuit (4) to measure a printed circuit board (5), a Zener diode (ZD) and an OP amplifier A current gain detector 6 configured of OP ₁ and resistors R ₁ -R ₅ to detect current gain with a base current Ib of the transistor Q ₁ inserted into the printed circuit board 5; And a current gain level adjuster configured of an OP amplifier OP ₂ (OP ₃ ), resistors R ₁ -R ₅ , and a switch circuit SW to adjust the level of the signal detected by the current gain detector 6. 7) a differential amplifier (8) and a differential amplifier (8), which are composed of an OP amplifier (OP ₄ ), resistors (R ₁₁ -R ₁₂ ) and variable resistors (VR ₁ ) for differentially amplifying the level adjusted current gain. The analog / digital converter (9) converts the output signal of the digital signal into a digital signal and supplies it to the storage device (2) to measure the current gain of the transistor inserted into the printed circuit board (5). Current gain rate measuring circuit of the transistor, characterized in that a.