JPS6235661A - Trimming method - Google Patents

Abstract

PURPOSE:To carry out trimming after predicting the positions and bits to be trimmed by a method wherein the potential of a test terminal, provided in addition to a trimming terminal, is controlled in several steps before trimming operation. CONSTITUTION:In a reference voltage generating circuit, the potential of a test terminal 19 is controlled before trimming operation and the output potentials of an output terminal 8 corresponding to the respectively controlled potentials of the output terminal 19 are measured and positions, bits and so forth which are to be trimmed are predicted in accordance with those measured values and then trimming is carried out. With this constitution, defects of trimming failures caused by errors of positions, bits and so forth which are to be trimmed induced by discrepancies from originally designed values owing to misjudgement, element variation and production deviation at the time of integrated circuits or the like are significantly reduced and can be suppressed to the minimum level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a trimming method, particularly in a trimming circuit that obtains a desired amplification gain by adjusting the values of resistors and/or capacitors. This relates to a method for predicting locations to be used and bits.

[Conventional technology]

There are many cases where it is necessary to precisely adjust the value to the originally desired value by trimming the integrated circuit or the like. For example, two digital-to-analog converters (hereinafter referred to as DAC), two analog-to-digital converters (hereinafter referred to as DAC),
When configuring a DAC (hereinafter referred to as human DC), the reference voltage of the DAC needs to be highly accurate and accurately obtain the desired absolute value in order to maintain high conversion accuracy of the DAC manufactured by the DC. . In such cases, conventionally, a technique called trimming has been used to adjust the amount of feedback of the reference voltage generating circuit to obtain a desired value.

FIG. 2 shows an explanatory diagram of a conventional example of a reference voltage generating circuit formed using integrated circuit technology. Figure 2 shows the output terminal (2001) of the stabilizing voltage generation circuit 1 and the output terminal (2002)
It is connected to the non-inverting input terminal IN of the operational amplifier 2 configured to form a feedback circuit to the inverting input terminal II (2003), and the resistor 30 is connected by trimming.
In the example of a resistor consisting of 1 to 308 areas, adjust the resistance ratio of the resistor Rs serving as the feedback resistor and the resistor R3 serving as the input resistor,
This is a reference voltage generation circuit that changes the amplification degree of the second operational amplifier to obtain a desired reference voltage. Here, in order to simplify the explanation, there are eight resistance ratio selection conditions. Further, in FIG. 2, 2 and 7 represent a buffer-connected operational amplifier, 8 represents an output terminal of a reference voltage generation circuit, and M
OS transistors 401-424 are inverting circuits 501-5
03 constitutes a selection circuit, and these selection circuits include a resistor 15 whose one end is connected to the positive voltage terminal 9 and the negative voltage terminal 16.
Three sets of high resistances 1001 to 10 connected in parallel between
03°Resistance 1101-1103. A series connection circuit of cutting parts 1201 to 1203 having a low resistance value, forgetting and trimming terminals 1301 to 1303. It is controlled by a trimmed circuit consisting of 14 areas. 2 in the reference voltage generation circuit.
The explanation will be made assuming that the MOS transistors 401 to 424 have N-type conduction characteristics. The state of this reference voltage generation circuit before trimming is that the connection point 20 between the high resistance 1001 and the resistance 1101 is the same as that at the connection point 20 between the high resistance 1001 and the resistance 1101, since the cutting portions 1201 to 1203 in the circuit to be trimmed are not cut.
11. Connection point 2012 between high resistance 1002 and resistance 1102
．． 2 and the connection point 201 between the high resistance 1003 and the resistance 1103
3 are all at low potential, and there are two inverting circuits 501 and 502.
-J6L Bi503 output 2014, 2015.2 work 2
01G each has a high potential. For this reason, MOS
Among the transistors 401 to 424, 401.402.
2 and 403 are in a conductive state, and the output terminal 2002 of the operational amplifier 2 is connected to the MOS transistors 401, 402 .
Inverting input terminal I of arithmetic increaser 11 lucky device 2 through 2-way 403! , 2003, and a resistor of 301°3.
02, . . . , connected to the ground potential 6 through 308,
The amplification degree of the operational amplifier 2 is 1, and the output voltage t of the stabilized voltage generation circuit 1 is outputted to the output terminal 8 of the reference voltage generation circuit.

Conventionally, in such a circuit, the voltage at the output terminal 8 is measured before trimming, and one of the cutting portions 1206, 1202, 2 cutting portions 1203, or a combination of these cutting portions is cut. We have decided to make a clear decision as to whether or not to use the trimming method. That is, before trimming, the output voltage of the reference voltage generation circuit at the output terminal 8 is measured, and from the measured value, the resistance ratio, that is, the amplification degree of the feedback circuit of the operational amplifier 2 is determined.
, 1202, and 1203 to be trimmed, and connect the trimming terminal 14 to the same potential as the low voltage quadruplets 16, and connect the trimming terminal 14 to the cut section to be trimmed, for example, in the case of 1201. 1
The cutting portion 1201 is cut by setting the terminal 301 to the same potential as the positive voltage terminal 8, and trimming is performed to obtain a desired reference voltage.

[Problem that the invention seeks to solve]

In the trimming work using the conventional trimming method described above, when determining the parts and bits to be trimmed, errors in judgment during trimming J) K.
Trimming may be applied to other parts or bits, or element fluctuations may occur during the manufacturing of integrated circuits, etc. that include circuits that obtain desired values by performing trimming, such as the reference voltage generation circuit in the conventional example mentioned above. , the resistance value of the resistors 301 to 308 due to manufacturing deviation, etc., and the value adjusted by trimming, such as the reference voltage value after trimming, may vary from the design value such as the amplification degree due to variations in circuit element constants. Originally, there was a drawback that there was a high probability that the desired value could not be obtained and the product would be defective.

[Means for solving problems]

The present invention controls the potentials of the trimming terminal K of the circuit to be trimmed and the test terminal provided separately from the IJ mink terminal in several stages, and performs trimming for each potential. It has a means for measuring the output of the power circuit and predicting and trimming the parts and bits to be trimmed based on the measured values.

〔Example〕

The present invention will be described in detail below with reference to the drawings, taking as an example a reference generation circuit formed by integrated circuit technology.

FIG. 1 shows an explanatory diagram of an embodiment of the present invention. Note that the same parts as in FIG. 2 shown as a conventional example are given the same numbers. That is, a selection circuit consisting of MOS transistors 401 to 424 and inverting circuits 501 to 503, a positive terminal 9, high resistances 1001 to 1003, and resistors 1101 to 110.
3. Cutting parts 1201 to 1203, trimming terminal 13
01-1303.14. Resistor 15 and negative voltage terminal 1
6, a connection point 2011 between the high resistor 1001 and the resistor 1101 is connected to each gate terminal of the MOS transistors 404, 410, 416, and 422 and the input terminal of the inverting circuit 501, and the high resistor 1002 The connection point 2012 between the
The output terminal 2019 of the human-powered OR circuit is connected to each gate terminal of the MOS transistors 408, 411, 420, and 423 and the input terminal of the inverting circuit 502.
3 and the resistor 1103 (7) connection point 2013 is connected to one input terminal of the two-man power OR circuit 17o2, and the output terminal 2020 of this two-man power OR circuit 1702 connects each of the MOS transistors 415, 418', and 421.424. The output terminal 2014 of the inverting circuit 501 is connected to each gate terminal of MOB transistors 401, 407, 413, and 419, and the output terminal 2o15 of the inverting circuit 502 is connected to the MOS transistor 402. , 405, 414, and 417, and the output terminal 2o16 of the inverting circuit 503 is connected to the gate terminals of M
OB) The test terminal 19 connected to each gate terminal of the transistors 403, 406, 409, and 412 is connected to the input terminal of the selector 18, and the first output terminal 20 of the selector 18
17 is connected to the other input terminal of the two-manpower OR circuit 1701, and the second output terminal 2018 of the selector 18 is connected to the other input terminal of the two-manpower OR circuit 1702. . Here, it is assumed that the selector 2 operates as shown in Table 1, and the resistor 301N307 has a unit resistance value R1, and the resistor 308 has a resistance value R2.

Margin below, 5.・↑[, Paka, Table 1 In the reference voltage generation circuit according to the above, before trimming, the potential of the test terminal 19 is controlled, and the output potential of the output terminal 8 of the reference voltage generation circuit is measured for each potential. Then, based on these measured values, the parts and bits that should be retrimmed are predicted and trimmed.
If the test terminal 19 is connected to a positive voltage power supply and set to 9, the first output terminal 2017 of the selector 18 as shown in Table 1.
, the second output terminal 2018 are both at low logic potential, 2
The output terminal 2o19 of the manual OR circuit 1701 has a low potential since the input terminal 2012 is at a low potential before trimming. Also, the output terminal 2020 of the two-manpower OR circuit 1702
Similarly, since the input terminal 2013 is at a low potential before trimming, it becomes a low potential. Even higher resistance 1001 and resistance 1
Since the connection point 2011 with the inverting circuits 501, 502 . and all outputs of 503 2014, 2015, respectively. and 2016 are high potential, MOS transistors 401, 402, 403, 405
,406,407,409゜412.413,414,
417 and 419 become conductive, and other MOB)
The transistor becomes non-conductive, and the output terminal 2002 of the operational amplifier 2 is connected to the inverting input terminal IE2003 through the MOS transistors 401 and 402. The output potential of the output terminal 8 at this time is set to Vngrl. Further, if the potential of the output terminal 2001 of the stabilizing voltage generation circuit 1 is ΔVT, and the output offset potential of the operational amplifier 7 is Vxo, then ΔvT=vREF1−vlOψday (1).

Next, when the test terminal 19 is connected to the ground potential, as shown in Table 1, the first output terminal 2017 of the selector 18 becomes a high logic potential, the second output terminal 2018 becomes a low logic potential, and the node 2011 and the node 2020 is at a low potential, and the node 2019 is at a high potential.
7,408,409゜411.412,413,419
, 420, and 423 become conductive, and other MOS)
The transistors are in a non-conducting state, and the resistors 302 and 30
The connection point 2005 with 3 is the M08 transistor 407,4
08.409 through operational amplifier two inverting input terminals 2
Connected to 003. Let the output potential of the output terminal 8 at this time be Va needle 2. Next, when the test terminal 19 is connected to a negative voltage power supply, as shown in Table 1, the first output terminal 2017 of the selector 18 becomes a low logic potential and the second output terminal 2018 becomes a high logic potential. Node 2011 and node 2019 have a low potential, and node 2020 has a high potential. For this reason, M
401,402 of OS transistors 401 to 424
,405.407,413゜414.415,417,
418, 419, 421, and 424 are in a conductive state, the other MOS transistors are in a non-conductive state, and the connection point 2007 between the resistor 304 and the resistor 305 is connected to the inverting input terminal 112003 of the operational amplifier 20 through the MOS transistors 413, 414, and 415. connected to. The output potential of the output terminal 8 at this time is Vnl+I! If it is 3, then it becomes. In addition, the connection point between the (11)th and nth resistors counting from the resistor 301 is connected to the inverting input terminal lI2003 of the operational amplifier 2 via three MOS transistors, and the output potential of the output terminal 8 is set to VR. Here, the feedback point at which the desired output voltage VRKF of the base single voltage generation circuit can be obtained is expressed by equation (4).
(5) Also, from equations (1), (2), and (3), Vlo
= VREF l−ΔV'r (6
), and the measured values VRIFI, VRIF 2, O! are obtained from the measurements shown in Figure 3 performed before trimming. Hi Vngr 3
j l) The location to be trimmed, bits, etc. for each circuit to be trimmed can be accurately determined by calculation.

Before performing trimming using Al1, it is possible to accurately predict the parts and bits to be trimmed without cutting any parts, for each circuit to avoid trimming and obtain the desired output, and then perform trimming after trimming. can be administered.

In addition, as can be seen from equations (1) to (8), the output voltage ΔTr of the stabilizing voltage generation circuit due to element variations in each circuit to obtain the desired output by trimming, manufacturing deviation, etc., and the output offset voltage Vro of the operational amplifier 7 and resistance 301~
Ratio R between resistance value R1 of resistor 307 and resistance value R2 of resistor 308
Even if there are variations in t/R1, etc., it is possible to accurately predict the location and bits to be trimmed.

〔Effect of the invention〕

As described above, by using the present invention, it is possible to accurately predict the parts and bits to be trimmed before trimming, and trimming can be performed afterward. It is possible to significantly reduce and minimize the occurrence of defects such as trimming failures due to errors in parts and bits that should be trimmed due to deviations from the originally designed value due to element variations and manufacturing deviations during manufacturing. can. Furthermore, the time spent on trimming can also be saved, making it very effective for applications such as integrated circuits.

Furthermore, it is obvious that the above-mentioned integrated circuit can be applied not only to semiconductor integrated circuits but also to hybrid integrated circuits. Furthermore, it is obvious that the number of test terminals provided separately from the trimming terminals is not limited to one, but that a plurality of test terminals may be provided to enable even more types of measurements.

Further, although this embodiment has been explained by taking trimming of a reference voltage generation circuit as an example, it is obvious that the present method can be used for trimming other types of circuits that obtain a desired output by performing other trimming.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional example. In the figure, 1... stabilizing voltage generation circuit,
2.7...Operation amplifier, 301-308.10
01S1003.1101-1103.15 ・-・
-Resistor, 401-424...MOS transistor, 501-503...Inverting circuit, 6...
...Ground potential, 8...Output terminal, 9...
... Positive voltage terminal, 1201-1203... Cutting section, 1301-1303.14... Trimming terminal, 16... Negative voltage terminal, 1701.17
02...2 human-powered OR circuit, 18...
Selector, 19...Test terminal, 2001-2
020... It is a node.

Claims (1)

[Claims] Before performing trimming on the trimming terminal of the circuit to be trimmed, the potential of a test terminal provided separately from the trimming terminal is controlled, and the voltage of the circuit to be trimmed is adjusted for each potential of the test terminal. A trimming method characterized by measuring the output, selecting the area to be trimmed based on the measured value, and performing the trimming.