JPH01162422A - Analog/digital converter - Google Patents

Abstract

PURPOSE:To improve converting accuracy by compensating a voltage error part due to a comparator input current and causing a divided voltage to be equal. CONSTITUTION:The title converter has first resistance R1-(n)-th resistance Rn (n=62) and this is a full-parallel type A/D converter to divide a reference voltage by the resistance. For example, a reference resistance 1 has a width W1 and a length l1 and it is composed of an AI film. Here, the resistance R1 is composed of the reference resistance 1 and the resistances R2-Rn are constituted of the resistance which adds a compensating resistance part 2 to compensate the voltage error part due to the input current of the comparator to the reference resistance 1. Thus, by adding the compensating resistance part to the respective reference resistances and causing the voltage, which is pressure- divided, to be equal, the converting accuracy can be improved.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an analog/digital converter, and particularly to a fully parallel analog/digital converter.

The purpose is to improve conversion accuracy.

The first resistor (R1) to the nth resistor (Rn(n-62)
), and divides a reference voltage by a resistor, the first resistor (R1) is constituted by a first reference resistor (1), and the second to nth The resistance (Rz~Rn (n=62)) is the first reference resistance (1
) with a compensation resistor section (2) that compensates for the voltage error caused by the comparator input current, and is characterized in that the resistance value gradually decreases from the first resistor to the nth resistor. It consists of an analog/digital converter.

[Industrial application field]

The present invention relates to an analog/digital converter (hereinafter referred to as an A/D converter), and particularly to a fully parallel type A/D converter.

There is a demand for improved conversion accuracy in such converters.

[Conventional technology]

In the conventional fully parallel A/D converter conversion method.

For example, when converting an analog signal to a 6-bit digital signal, a common method is to divide the reference voltage into 62 parts using a reference resistor made with one wire, and compare each potential with the analog voltage at once using 63 comparators. It is being

In this case, if the voltages divided by the reference resistors are not equal, conversion accuracy will decrease.

The voltage divided by the reference resistor is determined by the reference resistor and the current flowing through the reference resistor, but the current flowing through the two individual reference resistors causes an error equal to the input current of the comparator.

FIG. 3 shows a conventional example of an A/D converter.

R, l (n=1.2.'-..., 62) are reference resistances and are all equal. Let this value be Ro. In the figure, symbols have the following meanings.

IC = Comparator input current Ir: Current flowing into Vrb Vrt: Upper limit potential for conversion Vrb: Lower limit potential for conversion Vin: Analog input voltage to be A/D converted The voltage divided by the nth reference resistor is Vn(n =1.2.
, 62).

Vl = R111 = Ro (Ir+I c )V2
=R2I2 =Ro(Ir+21c)=V
1+-1'jo otsuj-c, -Vr+(n=61>-Rn (n=61) x I n (n=61)-R
o (Ir+611 c) -V, ten ball sub-Tj9-Q-I-+q, -Vn (n-
62) −Rn (n=62) x I n (n=[i 2)
=Ro (Ir+62I c ) -Vl 10-Danichi-R8o--3-L-(-. If Vl is used as a reference, the divided voltage will have an error as shown by the underline.

[Problem that the invention seeks to solve]

An object of the present invention is to provide an A/D converter that compensates for voltage errors caused by this comparator input current, equalizes the divided voltages, and improves conversion accuracy.

[Means for solving problems]

The first resistor (R1) to the nth resistor (Ro (n=62
)) and divides a reference voltage by a resistor, the first resistor (R+) being constituted by a first reference resistor (1), and the second to The resistance n (Rz to Rn (n=62)) is the first reference resistance (1
) with a compensation resistor section (2) that compensates for the voltage error caused by the comparator input current, and is characterized in that the resistance value gradually decreases from the first resistor to the nth resistor. The above problem is solved by the analog/digital converter.

[Effect]

In the first method of the present invention, the voltage V1 divided by R1 in FIG. 3 is used as a reference.

Vl = Ro XI H = Ro (Tr + Ic)
■To make 2 equal to ■1.

Since V2 = R2X (Ir +2 Ic),
V, = V2, then Rz = Ro x (Ir + Ic) / (Ir + 21c) = Ro
X (j Ic/ <Ir + 21c)) R3 = Ro x (Ir + Ic) / (Ir + 31c) = R
oX (1-21c/(Ir+31c))Rn
(n=61) - Ro x (Ir + Ic) / (Lr +61 re) =
RoX (1-60Ic/ (Ir +611c))Rn C
62) = Ro x (Ir + Ic) / (Ir + 62 Ic) = RoX (1611c/(Tr + 621c)) Therefore.

Rn=ROX (1(n-1)Ic/(Ir+n1c)).

(n-1) Ic/(Ir+n Ic) is the resistance to be compensated.

Therefore, by adding a compensation resistor to each reference resistor, it is possible to equalize the voltage divided into nine parts and improve conversion accuracy.

In the second method of the present invention, the voltage Vn (n=62) divided by R1 (n=62) in FIG. 3 is used as a reference.

In this case as well, the resistance to be compensated for in each divided portion can be determined by calculation similar to the first method.

In this case, the sign of the resistance to be compensated is opposite to that in the first case.

Therefore, in this case, by removing the correction resistance section from the reference resistance for correcting the resistance value, it is possible to equalize the voltage divided into nine and improve the conversion accuracy.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. 6
An example will be shown in which compensation or correction is applied to the reference resistance of the Vint A/D converter.

In Example 2, the width W1.
A first reference resistor 1 having a length of 11 is formed of an AI film. The value of this first reference resistance is defined as a first resistance R1 (-Ro). The second resistor R2 includes a compensating resistor 2 with a small volume added in parallel to the reference resistor R1.

Ro X Ic / (Ir +2 Ic) and lowers the J resistance value.

Similarly, in the case of Rn (n=62), Ro x (
Lower the resistance value by i 11c / (Ir +621c).

In Example 2, the width W2.
A second reference resistor 3 with a length of "21" is formed of an A1 film.The value of this reference resistor is R1 (n-62).R,, (n=
61) removes the correction resistor section 4 from the second reference resistor 3;

Increase the resistance value by RoXIc/(Ir+2Ic).

Correcting resistor section 4 to be sequentially removed in the same manner from n-61 onwards.
increase the volume of

In other words, if you look at it in another way, the compensation resistance section 2 is gradually added to the first resistor R1 even in the embodiment (I).
is basically equivalent.

The compensation resistor part 2 is added using the AI vacuum evaporation method, and the compensation resistor part 4
The removal can be performed using an L-rimming method using a laser or the like.

〔Effect of the invention〕

As explained above, according to the present invention, A with high conversion accuracy
/D converter can be provided.

[Brief explanation of the drawing]

FIG. 1 shows Example I. Figure 2 is an example ■. Figure 3 shows a conventional example of an A/D converter. It is. In the figure. l is the first reference resistance. 2 is a compensation resistance section. 3 is the second reference resistance. 4 is the correction resistance section R1 (=Kayatai Girin-I’O) (α) F’? :z=['? 0 (1-dark■) (b,) R62 = Bi. (1-≠ poison,) (C) i Mimon F Mariya Ita’3 Engineering Rod 1 mouth F’<b2 (=Thing 2 standard resistance gauge) (a) T? :Otsu I C’o) Implementation 4 da 1” ■ thousand and two mouths

Claims (1)

[Claims] The first resistor (R_1) to the nth resistor (R_n (n=6
2)) and divides a reference voltage by a resistor, the first resistor (R_1
) is composed of a first reference resistor (1), and the second to nth resistors (R_z to R_n (n=62)) compensate the voltage error due to the comparator input current to the first reference resistor (1). An analog/digital converter comprising a compensating resistor (2) added thereto, the resistance value of which gradually decreases from the first resistor to the n-th resistor.