JPH04273401A - Resistance train for dividing reference voltage - Google Patents

Abstract

PURPOSE:To eliminate the following at a resistance train, for reference-voltage dividing use, which is used at a digital-to-analog converter of R-string system or the like: an irregularity in individual resistances forming the resistance train; an irregularity in an Al contact resistance; and the difference in an Al interconnection resistance between a return point and a straight-line part. CONSTITUTION:At a resistance trainby this invention, Al contacts 1 as electrodes are installed at equal intervals in a continuous polysilicon resistance train 2, and their cut ends at the electrodes in the resistance-width direction are alternately perpendicular and they are arranged alternately to form resistance shapes. Thereby, the influence by an irregularity in Al interconnection resistances and Al contact resistances is eliminated, and a resistance pattern is not changed even at the return point of the resistance train. As a result, a reference voltage can be divided equally.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistor string for dividing a reference voltage, and more particularly to a resistor string for dividing a reference voltage used in a high-precision R-string type digital-to-analog converter or a voltage comparison type analog-to-digital converter. .

0002

2. Description of the Related Art A conventional resistor string for dividing a reference voltage, as shown in FIG.
It consists of a wiring 4 and a resistor 5 made of a polysilicon layer. Although the figure shows six resistor arrays R1 to R6, if the resistor array is long and cannot be arranged linearly due to the layout of the circuit, turning points such as R4 to R5 will exist.

0003

[Problems to be Solved by the Invention] In this conventional reference voltage dividing resistor array, in addition to variations in the polysilicon resistance itself, there are variations in contact resistance due to variations in the shape of the Al contact, and variations in the Al wiring resistance between the turning point and the straight part. There is a difference between

In particular, when one resistance value is set to a small value, variations in polysilicon resistance, variations in contact resistance, and variations in Al wiring resistance at the turning point become relatively non-negligible values, and the uniformity of the reference voltage division becomes impossible.

An object of the present invention is to provide a reference voltage dividing resistor string that solves the above problems.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the reference voltage dividing resistor string according to the present invention includes a polysilicon resistor and an electrode, and is configured to be an R-string type digital-to-analog converter. A reference voltage dividing resistor array that equally divides the reference voltage in a voltage comparison type analog-to-digital converter, etc. A polysilicon resistor is formed by continuously combining unit resistors, and the electrodes are equal to the polysilicon resistor. A unit resistor has a resistance shape in which the cut ends of the electrodes in the resistance width direction are perpendicular to each other, and are line symmetrical to one cut end of the electrode, or are arranged at the center of one cut end of the electrode. A resistance string is formed by connecting the cut end of one electrode to the cut end of the other electrode, or by connecting the cut end of one electrode to the cut end of the other electrode.A resistance string formed by a combination of unit resistors has a folded part similar to a straight part. The unit resistor pattern has a shape that is equally spaced, and the pattern of the unit resistor does not change.

[0007]

[Operation] The resistor string for dividing the reference voltage of the present invention divides the reference voltage by connecting successive resistors with Al wiring at equal intervals, without connecting each resistor in series with Al wiring. I'm taking it out. In addition, by making the polysilicon resistance layer meander, even at the turning point of the resistance string,
The resistance pattern has a shape that does not change.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram showing Embodiment 1 of the present invention. In the figure, Al contacts 1 are provided at equal intervals on a continuous polysilicon resistor 2, and these are used as electrodes.

By applying a reference voltage to both ends of the polysilicon resistor 2, divided voltages of the reference voltage equally divided by the Al contacts 1 serving as electrodes provided on the polysilicon resistor 2 at equal intervals can be obtained.

[0011] At this time, by making the ends of the electrodes in the resistor width direction perpendicular to each other and arranging them alternately, the individual resistors have the same shape in the folded part of the resistor row as in the straight part of the resistor row. All values are equal, allowing highly accurate division of the reference voltage.

(Embodiment 2) FIG. 2 is a diagram showing Embodiment 2 of the present invention. In this embodiment, a meandering polysilicon resistor 7 similar to that in the first embodiment is provided with Al contacts 6 as electrodes at intervals of every two unit resistors of the first embodiment.

According to this embodiment, as in the first embodiment, by applying a reference voltage to both ends of the polysilicon resistor 5, equally divided voltages of the reference voltage can be obtained.

This embodiment has the advantage that the value of one resistor is equal to the value of three resistors in the first embodiment, and variations in resistance values due to variations in the shape of the polysilicon resistor 5 are averaged out. be.

[0015]

[Effects of the Invention] As explained above, the reference voltage dividing resistor string of the present invention does not require any Al wiring between each resistor.
There is no influence of variations in Al wiring resistance and Al contact resistance. Further, there is no change in the resistance pattern at the turning point of the resistor string, which allows the reference voltage to be equally divided by the resistor string.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing Example 1 of the present invention.

FIG. 2 is a diagram showing Example 2 of the present invention.

FIG. 3 is a diagram showing a conventional example.

[Explanation of symbols]

1,6 Al contact 2,7 Polysilicon resistor

Claims (1)

[Claims] Claim 1: Comprising a polysilicon resistor and an electrode, R-
A resistor string for dividing the reference voltage equally in string-type digital-to-analog converters, voltage comparison-type analog-to-digital converters, etc., and a polyseries resistor is a series of resistors formed by combining unit resistors. The electrodes are arranged at equal intervals on a polysilicon resistor, and the unit resistor has a resistance shape in which the cuts of the electrodes in the resistance width direction are at right angles to each other, and the electrodes are line-symmetrical to one cut of the electrode. , or point symmetrical about the center of one cut of the electrode,
Alternatively, a resistance string is formed by connecting the cut end of one electrode to the cut end of the other electrode, and the resistance string formed by a combination of unit resistors has the same spacing in the folded part as in the straight part. A resistor string for dividing a reference voltage, characterized in that the pattern of the unit resistor has a shape that does not change.