JP3012280B2 - Function trimming method for hybrid integrated circuits - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a function trimming method for a hybrid integrated circuit for adjusting a circuit function of the hybrid integrated circuit by putting the hybrid integrated circuit into an operating state including peripheral circuits. More specifically, the offset adjustment of the operational amplifier that performs the main function of the integration circuit provided in the hybrid integrated circuit is performed by trimming an offset adjustment resistor provided in the operational amplifier, and The present invention relates to a function trimming method for a hybrid integrated circuit for trimming a function of an integrated circuit.

(Prior Art) Generally, a hybrid integrated circuit is a functional module in which passive elements such as a resistor, a capacitor or a coil, and active elements such as an analog IC or a digital IC are combined, so that the circuit function of the hybrid integrated circuit is adjusted. When performing, it is required to perform while checking and confirming the functions and characteristics comprehensively.

The function adjustment of the hybrid integrated circuit is performed by function trimming, in which the hybrid integrated circuit and peripheral circuits are put into an operating state, and the resistance value and the like are trimmed while measuring the signals of each part.

A typical example of an analog IC incorporated in the hybrid integrated circuit is an operational amplifier (hereinafter, referred to as an operational amplifier) having a differential amplifying function, and the operational amplifier receives a feedback from an output side to an input side. By doing
It has various circuit effects and has stable characteristics.

As a circuit using the operational amplifier, for example, an integration circuit for extracting a vertical synchronization signal of a video device is known.

Referring to FIG. 2, an integrator circuit for obtaining an output by integrating an input with an operational amplifier incorporated in the hybrid integrated circuit will be described.

An operational amplifier 5 having an inverting input terminal 6 and a non-inverting input terminal 7 has a negative bias terminal 8 and a positive bias terminal 9.
Power is supplied by being connected to the negative bias voltage -Vee and the positive bias voltage + Vcc, respectively.

An inverting input terminal 6 of the operational amplifier 5 is connected to an input terminal 3 provided in the hybrid integrated circuit 1 via an input resistor R1, and a non-inverting input terminal 7 is connected via an offset compensating resistor R2. In the hybrid integrated circuit 1, it is connected to a common potential terminal 11 serving as a reference potential.

Further, the output side of the operational amplifier 5 is connected to the output terminal 4.

The output side of the operational amplifier 5 connected to the output terminal 4 is connected to one end of a feedback capacitor C1 which is used for integration with the operational amplifier 5, and further connected to the feedback capacitor C1.
The other end of C1 is connected to the inverting input terminal 6 of the operational amplifier 5 to form a negative feedback loop.

When the operational amplifier 5 is operating, the negative feedback loop
Negative feedback is applied to the inverting input terminal 6 from the output side of the operational amplifier 5 via the feedback capacitor C1.

To the feedback capacitor C1, a series circuit including a low-frequency gain control resistor R4 and a phase compensation capacitor C2 is connected in parallel.

Both ends of an offset adjustment resistor R3 are connected to offset adjustment terminals 10a and 10b provided for offset adjustment of the operational amplifier 5.

The offset adjusting resistor R3 is an individual component having a slider, and the slider is connected to a positive bias terminal 9 biased to the positive bias potential + Vcc.

As described above, the integration circuit 2 including the operational amplifier 5 and the feedback capacitor C1 incorporated in the hybrid integrated circuit 1 is configured.

 Next, the circuit operation of the integration circuit 2 will be described.

When an input voltage is input to the input terminal 3 using the common potential terminal 11 as a reference potential, an input current determined by the input resistance R1 flows.

The input current flows into the feedback capacitor C1 and charges the feedback capacitor C1 because the input impedance of the inverting input terminal 6 of the operational amplifier 5 is very large.

As the feedback capacitor C1 is charged by the input current, an output voltage obtained by integrating the input voltage is output to the output terminal 4 connected to the output side of the operational amplifier 5.

At this time, the low-frequency gain control resistor R4 is provided to limit the closed-loop gain in the low frequency region, and the phase compensation capacitor C2 is provided to prevent self-oscillation in the high frequency region. .

In the operational amplifier 5 in the integration circuit 2, an offset voltage is generated due to the imbalance of the transistors and FETs, which are constituent elements of the operational amplifier 5.

In order to adjust the offset voltage, for example, an individual offset adjusting resistor R3 (a variable resistor, also referred to as a trimmer resistor) is attached to the operational amplifier 5 to adjust the offset voltage.

In the case of performing the offset adjustment in the function trimming of the hybrid integrated circuit 1, the input terminal 3 of the operational amplifier 5 is connected to the negative feedback loop of the operational amplifier 5 because the capacitive feedback capacitor C1 is interposed in the negative feedback loop. , An AC input voltage (including a pulsating current that is a DC value) is input, and the offset adjustment resistor R3 is adjusted while measuring the AC output voltage output to the output terminal 4 to adjust the offset of the operational amplifier 5. It is carried out.

At this time, the offset adjustment resistor R3 is an individual component, and is performed by inserting a driver into an adjustment groove or the like provided in the offset adjustment resistor R3 and rotating the adjustment groove.

In some cases, the offset adjusting resistor R3 is formed by a screen printing firing method, an AC input voltage is input to the operational amplifier 5, and trimming is performed using a laser or an abrasive trimming device.

However, according to the conventional function trimming method for a hybrid integrated circuit, in an integrating circuit including an operational amplifier and a feedback capacitor, when the offset adjustment of the operational amplifier is performed, Since the feedback loop is AC-coupled to the feedback loop via the feedback capacitor, the AC input voltage must be input to the inverting input terminal and the non-inverting input terminal of the operational amplifier, and the function trimming is performed. There is a problem that an AC signal source or the like is required depending on the situation.

Further, since the offset adjustment of the operational amplifier is performed by rotating and adjusting the individual offset adjustment resistors connected to the offset adjustment terminals of the operational amplifier with a driver or the like, the adjustment takes time and effort.
There is a problem that the process is complicated and individual errors are caused by the adjustment operator.

Further, the offset adjusting resistor of the operational amplifier is
When formed by screen printing and then trimmed by a trimming device, the output voltage to be measured has an AC value, so the read time of the AC output voltage required by the trimming device is shorter than the DC output voltage. However, there is a problem that a dedicated measuring instrument is required.

The present invention has been made in view of the above circumstances, and does not require the provision of an individual offset adjustment resistor for adjusting the offset of an operational amplifier provided in a hybrid integrated circuit, and furthermore, has a thickness formed by a screen printing firing method. It is an object of the present invention to provide a function trimming method for a hybrid integrated circuit that can be performed by trimming a film resistor.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method in which feedback is applied from an output side to an input side of an operational amplifier via a capacitive element between the input side and the output side. A function trimming method for a hybrid integrated circuit having an integration circuit in which an integration operation of an input voltage becomes an output voltage, wherein a probing portion is provided on an input side and an output side of the operational amplifier, and the function trimming is performed between probes contacting the probing portion A resistor for trimming the offset adjustment resistor connected to the operational amplifier while detecting the input voltage and output voltage of the operational amplifier while passing the resistor in parallel with the capacitive element. Function trimming.

(Function) In the present invention, in an integration circuit configured by applying a feedback from an output side to an input side of an operational amplifier provided in a hybrid integrated circuit by a feedback loop via a feedback capacitor, Probing terminals are provided on the input side and the output side, respectively, and a probe of a trimming device is brought into contact with the probing terminals, so that a function trimming resistor provided between the probes forms a feedback loop in parallel with the feedback capacitor. And the feedback loop can be changed from a capacitive AC coupling to a DC coupling via a resistor.

Therefore, when the offset of the operational amplifier of the integrating circuit is adjusted, the DC input voltage can be input to the operational amplifier instead of the AC input voltage, and the output voltage can be easily measured by the trimming device.

However, offset adjustment of the operational amplifier can be performed by forming the offset adjusting resistor of the operational amplifier by a thick film screen printing firing method and trimming the laser or an abrasive trimming device. .

(Example) An example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a function trimming method for a hybrid integrated circuit according to the present invention.

An operational amplifier 25 having an inverting input terminal 26 and a non-inverting input terminal 27 has a negative bias terminal 28 and a positive bias terminal 29,
Power is supplied by being connected to the negative bias voltage -Vee and the positive bias voltage + Vcc, respectively.

An inverting input terminal 26 of the operational amplifier 25 is connected to an input terminal 23 provided in the hybrid integrated circuit 21 via an input resistor R1, and a non-inverting input terminal 27 is connected via an offset compensating resistor R2. The output of the operational amplifier 25 is connected to an output terminal 24, which is connected to a common potential terminal 31 serving as a reference potential in the hybrid integrated circuit 21.

The output side of the operational amplifier 5 is connected to one end of a feedback capacitor C1 that provides an integrating action together with the operational amplifier 5, and the other end of the feedback capacitor C1 is connected to the operational amplifier 5.
, A negative feedback loop is formed.

The negative feedback loop, when the operational amplifier 25 is in operation,
Negative feedback is applied to the inverting input terminal 26 from the output side of the operational amplifier 25 via the feedback capacitor C1.

To the feedback capacitor C1, a series circuit including a low-frequency gain control resistor R4 and a phase compensation capacitor C2 is connected in parallel.

Further, one ends of offset adjustment resistors R5 and R6 are connected to offset adjustment terminals 30a and 30b provided for offset adjustment of the operational amplifier 25, respectively, and the other ends of the offset adjustment resistors R5 and R6 are Connected in common.

The commonly connected node of the offset adjusting resistors R5 and R6 is connected to the positive bias terminal 29 and is biased to a positive bias voltage + Vcc.

The offset adjusting resistors R5 and R6 are thick-film resistors formed by a thick-film screen printing baking method or the like.

The operational amplifier 25 incorporated in the hybrid integrated circuit 21 as described above
And an integration circuit 22 including a feedback capacitor C1 and the like.

 Next, the circuit operation of the integration circuit 22 will be described.

When an input voltage is input to the input terminal 23 using the common potential terminal 31 as a reference potential, an input current determined by the input resistance R1 flows.

The input current flows into the feedback capacitor C1 and charges the feedback capacitor C1 because the input impedance of the inverting input terminal 26 of the operational amplifier 25 is very large.

The output terminal connected to the output side of the operational amplifier 25 by charging the feedback capacitor C1 with the input current.
An output voltage obtained by integrating the input voltage is output to 24.

At this time, the low-frequency gain control resistor R4 is provided to limit the closed-loop gain in the low frequency region, and the phase compensation capacitor C2 is provided to prevent self-oscillation in the high frequency region. .

In the operational amplifier 25 in the integration circuit 22, an offset voltage is generated on the output side due to imbalance of the transistors and FETs, which are constituent elements of the operational amplifier 25, and the offset voltage is generated by the operational amplifier 25, the feedback capacitor C1, and the like. The offset voltage needs to be adjusted because the integration function may be affected.

The offset voltage adjustment of the operational amplifier 25
This can be performed by trimming the offset adjustment resistors R5 and R6 provided in the 25 offset adjustment terminals 30a and 30b.

Therefore, the probing terminals 32a and 32b provided on the input side and the output side of the operational amplifier 25 are respectively brought into contact with probes 33a and 33b provided in a laser trimming device 34 having a laser beam irradiation unit (not shown). Then, the offset adjusting resistors R5 and R6 are laser trimmed while measuring the input voltage and the output voltage.

At this time, the probes 33a and 33b of the laser trimming device 34
In between, a resistor R7 for function trimming is provided, so that an AC coupling in which negative feedback is applied from the output side of the operational amplifier 25 to the inverting input terminal 26 via the feedback capacitor C1,
By connecting the function trimming resistor R7 in parallel with the feedback capacitor C1, the feedback loop becomes a DC coupling.

However, with reference to the common potential terminal 31 provided in the integration circuit 22, a DC input voltage is input to the input terminal 23 of the operational amplifier 25, and the DC output voltage output to the output terminal 24 of the operational amplifier 25 is The offset adjustment of the operational amplifier 25 can be performed by performing the laser trimming of the offset adjustment resistors R5 and R6 while performing the measurement by the laser trimming device.

As described above, according to the present embodiment, the offset adjustment of the operational amplifier 25 which performs the main operation of the integration circuit 22 is performed by the operational amplifier.
A DC input voltage is input to input terminal 23 of 25, and the operational amplifier
The offset adjustment resistors R5 and R6 provided in the operational amplifier 25 are laser-trimmed while measuring the DC output voltage output to the output terminal 24 of the 25 to adjust the offset of the operational amplifier 25. This eliminates the need for an AC power supply and eliminates the need for a difficult measuring means for measuring an AC signal.

Further, since the offset adjustment resistors R5 and R6 provided at the offset adjustment terminals 30a and 30b of the operational amplifier 25 are formed of thick film resistors, the offset adjustment resistors R5 and R6 are formed.
Since R5 and R6 can be functionally trimmed together with other thick film resistors in the hybrid integrated circuit 21, individual variable resistance components and the like are not required, and complicated adjustment of the variable resistance can be eliminated.

It is to be noted that the laser trimming device 34 is not limited to use for trimming the offset adjustment resistors R5 and R6, but is an abrasive that injects glass particles or the like and trims the resistance values of the offset adjustment resistors R5 and R6. A trimming device may be used.

(Effect of the Invention) The function trimming method for a hybrid integrated circuit according to the present invention has the following effects because it is configured as described above.

(A) Offset adjustment of an operational amplifier is performed by providing a probing terminal on each of the input side and the output side of the operational amplifier, and applying a probe of a trimming device having a functional trimming resistor between the probe to the probing terminal. The operational amplifier is offset by adjusting the feedback loop from the output side to the input side of the operational amplifier into a DC coupling, and trimming the offset adjusting resistor made of a thick film attached to the operational amplifier. Therefore, there is no need to input an AC input voltage for offset adjustment, and there is an excellent effect that an AC signal source becomes unnecessary.

(B) In addition, since the offset adjustment resistor used for offset adjustment of the operational amplifier is formed by a thick film screen printing baking method or the like, an individual offset adjustment resistor is not required, and component costs can be reduced. Since the offset adjustment can be performed together with the function trimming process of other thick film resistors provided in the hybrid integrated circuit, the efficiency of the function trimming process can be improved, and furthermore, it is possible to prevent the occurrence of personal errors by the adjustment operator. Has an effect.

(C) Furthermore, the function for trimming the offset adjusting resistor of the operational amplifier can be performed by the DC input voltage without the need for the AC input voltage, so that the reading time for measuring the DC input voltage by the trimming device is reduced. In addition, there is an excellent effect that a dedicated measuring instrument or the like becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a function trimming method for a hybrid integrated circuit according to the present invention, and FIG. 2 is a circuit diagram showing a conventional function trimming method for a hybrid integrated circuit. 21: hybrid integrated circuit, 22: integrating circuit, 25: operational amplifier, 26: inverting input terminal, 27: non-inverting input terminal, 30a, 30b: offset adjustment terminal, 32a, 32b: probing terminal , 33a, 33b… Probe, R5, R6… Offset adjustment resistance, R7… Function trimming resistance, C1… Feedback capacitor.

Claims (1)

(57) [Claims] A hybrid circuit having an integrating circuit in which an input voltage is fed back to an input side via a capacitive element between an input side and an output side of an operational amplifier so that an integration operation of an input voltage becomes an output voltage. In a method for trimming a function of an integrated circuit,
Probing sections are provided on the input side and output side of the operational amplifier, and a function trimming resistor is interposed between the probes contacting the probing section so as to be in parallel with the capacitive element. A function trimming method for a hybrid integrated circuit, comprising trimming a function of the hybrid integrated circuit by trimming an offset adjusting resistor connected to an operational amplifier while detecting a voltage.