JP2000196370A - Distortion control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To freely control secondary distortion in a secondary distortion control circuit such as an inverting amplifier constituted by using a non-linear resistance. SOLUTION: In this distortion control circuit, a combined resistance R12 which is formed on an integrated circuit substrate and constituted by serially connecting two kinds of resistances R1 and R2 whose non-linear coefficients are different is connected between a Vi input terminal and the inversion input terminal of an operational amplifier OP11. Also, a combined resistances k.R21 constituted by serially connecting resistances k.R1 and k.R2 having the same resistance ratio as the ratio of the resistances R1 and R2 is connected between the inversion input terminal and a Vo output terminal. At that time, the positions of the two resistances are changed or the ratio of each resistance is changed in each combined resistance R12 and k.R21 so that the secondary distortion of the operational amplifier OP11 can be freely controlled within a fixed range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distortion control circuit, and more particularly to a secondary distortion control circuit such as an inverting amplifier constituted by using a nonlinear resistor and an operational amplifier.

[0002]

2. Description of the Related Art As is well known, a resistor formed on an integrated circuit substrate often has a non-linear characteristic with respect to a voltage applied to both ends thereof. Also, on the integrated circuit board,
It is also well known that a plurality of types of resistors having different voltage dependencies can be provided together.

FIG. 8 shows a schematic configuration of a diffusion or ion implantation resistor provided on an integrated circuit substrate.

In this case, a resistor (N + impurity region) 102 is formed on the surface of the P-type substrate 101 by diffusing or ion-implanting an N-type impurity at a high concentration. Then, Al electrodes 104, 104 connected to the resistor 102 are provided via an oxide film 103 provided so as to cover the entire surface.

This resistor 102 is connected to the Al electrode 104,
A power supply V is connected between the transistors 104 and a reverse voltage is applied to the PN junction (the PN junction is set to a reverse potential) to electrically insulate the P-type substrate 101 from the P-type substrate 101.

For this reason, as shown in FIG. 1, when the reverse voltage applied to the PN junction is large, the depletion layer 105 at the PN junction expands greatly. As a result, the resistance 10
2 becomes smaller, and the resistor 102 has voltage dependency. The magnitude of the voltage dependency of the resistor 102 changes depending on the diffusion concentration and the diffusion depth (or the implantation concentration and the implantation depth).

FIG. 9 shows a schematic configuration of a conductive thin film resistor using a polysilicon thin film provided on an integrated circuit substrate.

For example, a resistor 2 made of a polysilicon thin film is formed on the surface of a P-type substrate 201 through an oxide film 202.
03 is provided. Also, Al electrodes 204, 204 are provided at both ends of the resistor 203, respectively.

In this case, the resistance 203 is insulated from the substrate 201 by the oxide film 202. For this reason,
There is no voltage dependency due to the expansion of the depletion layer, and the nonlinear coefficient is often much smaller than that of the diffusion resistance or ion implantation resistance.

Note that the resistor 203 is not limited to a polysilicon thin film, but may be formed using a tungsten thin film or the like.

As described above, a plurality of types of resistors having different voltage dependencies can be mixedly formed on an integrated circuit substrate.

Hereinafter, the voltage dependence of the resistance will be considered.

The voltage dependency of the resistor 102 shown in FIG.
It changes continuously in the length direction of the resistor 102. Therefore, for the sake of simplicity, for example, as shown in FIG.
Analyzed by dividing into n.

For example, the i-th resistor ri in the resistors r1 to rn can be written as ri = ro [1 + Δ (i / n) V]. Here, ro is the value of ri at V = 0 (that is, at V = 0, r1 = r2 =... = Rn =
ro). Δ represents a nonlinear coefficient.

From this, if n is sufficiently large, R = Σri = n · ro [1 + Δ · V / n ² · Σi] for the entire resistance R. Here, Σ represents the sum of 1 to n for i.

[0016] In addition, Σi is a Σi = [n · (n + 1)] / 2, if n is sufficiently large, and Σi = n ^2/2.

Here, assuming that n · ro = Ro, FIG.
As shown in (2), when the midpoint potential V / 2 of the resistor R is used, the resistor R can be set as follows: R = Ro (1 + Δ · V / 2).

FIG. 12 shows an example in which an inverting amplifier is constructed using this nonlinear resistor.

That is, the Vi input terminal is connected to the inverting input (-) terminal of the operational amplifier (operational amplifier) OP1 via the resistor R1. Also, this inverting input terminal and V
A resistor R2 is connected to the output terminal o, and the output of the operational amplifier OP1 is fed back via the resistor R2. On the other hand, the non-inverting input (+) end of the operational amplifier OP1 is grounded.

In this case, the midpoint potential of the resistor R1 is Vi /
2. Since the midpoint potential of the resistor R2 is Vo / 2, the following equation holds.

R1 = R1o (1 + ΔVi / 2) R2 = R2o (1 + ΔVo / 2) From the relationship between Vo and Vi, Vo = − (R2 / R1) Vi = − (R2o / R1o) Vi [( 1 + ΔVo / 2) / (1 + ΔVi / 2)] If ΔVo / 2 << 1, ΔVi / 2 << 1, then
The following equation approximately holds.

Vo = − (R2o / R1o) Vi [1 + Δ
(Vo−Vi) / 2] Here, Vo = − (R2o / R1
o) is approximated by Vi, and put the Go = R2o / R1o, Vo = -Go · Vi [1-Δ (1 + Go) Vi / 2] = -Go · [Vi-Δ (1 + Go) Vi 2/2] and Become.

Here, a sine wave is considered as an input signal.

Vi = A sin ωt Vi ² = A ² sin ² ωt = A ² (1−cos 2ωt) / 2 From this, Vo = −Go · A [sin ωt−Δ (1 + Go) A (1)
−cos2ωt) / 4] cos2ωt on the right side of the above equation indicates the second harmonic.
Therefore, if the second harmonic distortion factor is set to 2HD, 2HD = −Δ (1 + Go) A / 4 where the negative sign indicates the phase relationship where the fundamental wave is sincot and the second harmonic is −cos2ωt. It shows that there is.

In the inverting amplifier, since the nonlinear coefficient Δ is determined by the type of the resistor, the second harmonic distortion factor 2HD
Can be controlled by changing Go. But G
o is the gain of this inverting amplifier. Usually, the gain is designed to be constant, so that the gain cannot be changed in most cases. That is, in the conventional inverting amplifier using one type of resistor, a constant second harmonic distortion rate is obtained due to the inherent nonlinear coefficient of the resistor, and it is impossible to control this.

Next, consider the case where different types of resistors are used for the resistors R1 and R2 (inverting amplifier).
In this case, the nonlinear coefficient Δ of each of the resistors R1 and R2
R1 = R1o (1 + Δ1 · Vi / 2) R2 = R2o (1 + Δ2 · Vo / 2) From the relationship between Vo and Vi, Vo = − (R2 / R1) Vi = − (R2o / R1o ) Vi [(1 + Δ2 · Vo / 2) / (1 + Δ1 · Vi / 2)] Assuming that Δ2 · Vo / 2 << 1, Δ1 · Vi / 2 << 1, the following equation approximately holds. .

Vo =-(R2o / R1o) Vi [1+
(Δ2 · Vo−Δ1 · Vi) / 2] Here, Vo = − (R2o / R1
o) When approximating by Vi, Go = R2o / R1o. Therefore, when approximating by Vo = −Go · Vi with respect to Vo on the right side of the above equation, Vo = −Go · Vi [1− (Δ2 · Go + Δ1) Vi / 2] = the -Go · [Vi- (Δ2 · Go + Δ1) Vi 2/2].

Here, a sine wave is considered as an input signal.

[0029] ^{Vi = Asinωt Vi 2 = A 2} sin 2 ωt = A 2 (1-cos2ωt) / 2 than this, Vo = -Go · A [sinωt- (Δ2 · Go + Δ1)
A (1−cos2ωt) / 4] cos2ωt on the right side of the above equation indicates the second harmonic.
Therefore, if the second harmonic distortion factor is set to 2HD, then 2HD = − (Δ2 · Go + Δ1) A / 4 This second harmonic distortion factor 2HD becomes 0 if the relationship Δ1 = −Δ2 · Go holds.

Also, depending on how the resistors R1 and R2 are combined with a resistor having a nonlinear coefficient of .DELTA.1 and a resistor of .DELTA.2, as shown in Table 1 below, the second-order harmonic distortion is to some extent. The rate 2HD can be controlled.

[0031]

[Table 1]

As described above, in the case of the inverting amplifier, the resistance R1
By using different types of resistors for the resistor R2 and the resistor R2, the secondary distortion can be controlled to some extent.

However, although the value of the resistor formed on the integrated circuit board is controlled within a certain range during mass production, the range of its variation cannot be generally ignored. Also, since there is generally no correlation between the variations in the different resistances, for example, the resistance R1 and the resistance R2 are each ± 30 without correlation.
%, The variation of the gain is 0.7 · R20 / (1.3 · R10) <Go <1.3 ·
R20 / (0.7 · R10) 0.54 · R20 / R10 <Go <1.9 · R20 / R
It becomes 10.

Here, R10 is the design value of the resistor R1, R2
0 is a design value of the resistor R2. In this example, the design value of 5
The gain in mass production varies from 4% to 190%.

As described above, since the gain greatly varies, it is difficult to use different types of resistors for the resistors R1 and R2. That is, in the case of a conventional inverting amplifier using two types of resistors, distortion can be controlled to some extent, but variation in gain becomes very large. Therefore, controlling distortion by this method has a great disadvantage.

FIG. 13 shows an example in which a non-inverting (forward) amplifier is formed by using the above-mentioned nonlinear resistor.

That is, the Vi input terminal is connected to the operational amplifier O
It is connected to the non-inverting input terminal of P2. Operational amplifier OP
The two inverting input terminals are grounded via a resistor R1. Further, a resistor R2 is connected between the inverting input terminal and the Vo output terminal, so that the output of the operational amplifier OP2 is fed back via the resistor R2.

In this case, the midpoint potential of the resistor R1 is Vi /
2. Since the midpoint potential of the resistor R2 is (Vi + Vo) / 2, the following equation holds.

R1 = R1o (1 + ΔVi / 2) R2 = R2o [1 + Δ (Vi + Vo) / 2] From the relationship between Vo and Vi, again, Go = R2o / R
Assuming 1o, Vo = (1 + R2 / R1) Vi = Vi + Go · Vi ｛[1 + Δ (Vi + Vo) / 2] / (1 + ΔVi / 2)｝ Δ (Vi + Vo) / 2 << 1, ΔVi / 2 << 1 If so, the following equation approximately holds.

Vo = Vi + Go · Vi (1 + Δ · Vo / 2) Here, when Vo on the right side of the above equation is approximated by Vo = (1 + Go) Vi, Vo = Vi + Go · Vi [1 + Δ (1 + Go) Vi / 2] = (1 + Go) Vi + Go · (1 + Go) Δ · Vi 2/2 = (1 + Go) become (Vi + Go · Δ · Vi 2/2).

Here, a sine wave is considered as an input signal.

Vi = A sin ωt Vi ² = A ² sin ² ωt = A ² (1−cos 2ωt) / 2 From this, Vo = (1 + Go) · A [sin ωt + Go · Δ · A
(1−cos2ωt) / 4] cos2ωt on the right side of the above equation indicates a second harmonic.
Therefore, assuming that the second harmonic distortion factor is 2HD, 2HD = −Go · Δ · A / 4 Here, the negative sign indicates that the fundamental wave is 2ω with respect to sinωt.
This shows that the second harmonic has a phase relationship of -cos2ωt.

Also in the non-inverting amplifier, the nonlinear coefficient Δ is determined by the type of the resistor.
In order to control the HD, Go may be changed. However, 1 + Go is the gain of the non-inverting amplifier. Usually, the gain is designed to be constant, so that the gain cannot be changed in most cases. That is, in the conventional non-inverting amplifier, a constant 2
It became the second harmonic distortion rate, and it was impossible to control this.

Next, as in the case of the above-described inverting amplifier, in the non-inverting amplifier, the resistors R1 and R2 are connected to each other.
Consider the case where different types of resistors are used. Also in this case, since the nonlinear coefficients of the respective resistors R1 and R2 are different, R1 = R1o (1 + Δ1 · Vi / 2) R2 = R2o [1 + Δ2 · (Vi + Vo) / 2] From the relationship between Vo and Vi, Go = R2o / R
Assuming 1o, Vo = (1 + R2 / R1) Vi = Vi + Go · Vi ｛[1 + Δ2 · (Vi + Vo) / 2] / (1 + Δ1 · Vi / 2)｝ Δ2 · (Vi + Vo) / 2 << 1, Δ1 · Vi / 2 <<
If it is 1, the following equation approximately holds.

Vo = Vi + Go · Vi [1 + Δ2 · (Vi + Vo) / 2−Δ1 · Vi / 2] = Vi + Go · Vi [1+ (Δ2−Δ1) · Vi / 2 + Δ2 · Vo / 2] Here, the right side of the above equation Is approximated by Vo = (1 + Go) Vi. Vo = Vi + Go · ViＶ1 + [(Δ2-Δ1) + Δ2 · (1 + Go)] · Vi / 2｝ = (1 + Go) Vi + Go [Δ2 · (2 + Go) − ^{Δ1] Vi 2/2 = (} 1 + Go) a (Vi + Go · Δ '· Vi 2/2). Δ ′ = [Δ2 · (2 + Go) −Δ1] /
(1 + Go).

Here, a sine wave is considered as an input signal.

Vi = A sin ωt Vi ² = A ² sin ² ωt = A ² (1−cos 2ωt) / 2 From this, Vo = (1 + Go) · A [sin ωt + Go · Δ ′ · A
(1−cos2ωt) / 4] cos2ωt on the right side of the above equation indicates a second harmonic.
Therefore, assuming that the second harmonic distortion factor is 2HD, 2HD = −Go · Δ ′ · A / 4 = −Go · A [Δ2 · (2 + Go) −Δ1] / [4 (1 + Go)] The wave distortion factor 2HD is Δ1 = −Δ2 · (2 + G
If the relation of o) is established, it becomes 0.

Further, as shown in Table 2 below, to some extent, the second harmonic distortion depends on how the resistors R1 and R2 are combined with a resistor having a nonlinear coefficient of Δ1 and a resistor of Δ2. The rate 2HD can be controlled.

[0049]

[Table 2]

Thus, in the case of the non-inverting amplifier, the resistance R
By using different types of resistors for 1 and the resistor R2, the secondary distortion can be controlled to some extent.

However, even in the case of a non-inverting amplifier, the value of the resistance formed on the integrated circuit board is controlled within a certain range during mass production, but the range of variation cannot be generally ignored. Further, since there is generally no correlation between the variations in the resistances, the gain greatly varies as in the case of the inverting amplifier. Therefore, in the case of a conventional non-inverting amplifier using two types of resistors, the distortion can be controlled to some extent, but the variation in gain becomes very large, so that controlling the distortion by this method has a great disadvantage.

FIG. 14 shows an example in which a differential amplifier is formed by using the above-mentioned nonlinear resistor.

That is, the Vm input terminal is connected to the inverting input terminal of the operational amplifier OP3 via the resistor R1. A resistor R2 is connected between the inverting input terminal and the Vo output terminal, and the output of the operational amplifier OP3 is fed back via the resistor R2.

On the other hand, the Vp input terminal is connected to the non-inverting input terminal of the operational amplifier OP3 via the resistor R3. The non-inverting input terminal is grounded via the resistor R4.

In this case, the midpoint potential of the resistor R1 is (Vm +
Vi) / 2 and the midpoint potential of the resistor R2 is (Vo + Vi) /
2. The midpoint potential of the resistor R3 is (Vp + Vi) / 2,
Since the midpoint potential of No. 4 is Vi / 2, the following equation holds.

R1 = R1o [1 + Δ (Vm + Vi) / 2] R2 = R2o [1 + Δ (Vo + Vi) / 2] R3 = R3o [1 + Δ (Vp + Vi) / 2] R4 = R4o (1 + ΔVi / 2) Since it is a differential amplifier. , Vm = −Vp, R3o = R1o, R
4o = R2o, and here again, Go = R2o / R1o.

Further, for simplicity, the above R1 to R4
In the expressions on the right side, Vi and Vo on the right side are as follows: Vi = Vp · R4 / (R3 + R4) = Vp · R4o / (R3o + R4o) = Vp · R2o / (R1o + R2o) = Vp · Go / (1 + Go) Vo = 2 · Go・ Substitute Vp. Then, the above equations R1 to R4 are as follows.

R1 = R1o [1 + Δ (Vm + Vi) / 2] = R1o {1 + Δ [−Vp + Vp · Go / (1 + Go)] / 2} = R1o {1−Δ · Vp · Go / [2 (1 + Go)]} = R1o (1−Δ · k1) where k1 = Vp / [2 (1 + Go)] R2 = R2o [1 + Δ (Vo + Vi) / 2] = R2o ｛1 + Δ [2 · Go · Vp + Vp · Go / (1 + Go)] / 2 ＝= R2o ｛1 + Δ · Vp · Go (2Go + 3) / [2 (1 + Go)]｝ = R2o (1 + Δ · k2) where k2 = Vp · Go (2Go + 3) / [2 (1 + Go)] = k1 · Go · ( 2Go + 3) R3 = R3o [1 + Δ (Vp + Vi) / 2] = R3o {1 + Δ [Vp + Vp · Go / (1 + Go)] / 2} = R1o ｛1 + Δ · Vp (2Go + 1) / [2 (1 + Go)]｝ = R1o (1 + Δ · k3) where k3 = Vp · (2Go + 1) / [2 (1 + Go)] = k1 · (2Go + 1) R4 = R4o (1 + Δ · Vi / 2) = R2o ｛1 + Δ · Vp · Go / [2 (1 + Go) )]｝ = R2o (1 + Δ · k4) where k4 = Vp · Go / [2 (1 + Go)] = k1 · Go The relational expression between Vo and Vp is: Vo = (R2 / R1) ｛(R1 + R2) R4 · Vp / [R2 (R3 + R4)] − Vm｝ = Vp · [R4 (R1 + R2) + R2 (R3 + R4)] / [R1 (R3 + R4)] = Vp · Go [1 + Δ (k4 + k12) + 1 + Δ (k2 + k34)] / [1 + Δ ( k1 + k34)] == Vp · 2 · Go ｛1 + Δ (k2 + k4 + k12 + k34) / 2] / [1 + Δ (k1 + k34)]｝ = Vp · 2 · Go ｛1 + Δ [(k2 + k4 + k12 + k3) ) −2− (k 1 + k34)]｝ = Vp · 2 · Go [1 + Δ (k2 + k4 + k12−k34−2k1) / 2] where k12 = (R2o · k2−R1o · k1) / (R1o + R2o) = (Go · k2) -k1) / (1 + Go) = [Go · k1 · Go · (2Go + 3) -k1] / (1 + Go) = k1 [Go 2 · (2Go + 3) -1] / (1 + Go) = k1 [2Go 3 + 3Go 2 -1 ] / (1 + Go) = k1 (2Go 2 + Go-1) k34 = (R1o · k3 + R2o · k4) / (R1o + R2o) = (k1 · (2Go + 1) + k1 · Go 2) / (1 + Go) = k1 [(2Go + 1) + Go ² ] / (1 + Go) = k1 (1 + Go). Therefore, k2 + k4 + k12-k34-2k1 = k1 · Go · (2Go + 3) + k1 · Go + k1 (2Go 2 + Go-1) -k1 (1 + Go) -2k1 = k1 [Go · (2Go + 3) + Go + (2Go 2 + Go-1) - ( 1+ Go) -2] = k1 (a ^{4Go 2 + 4Go) = 4 ·} Vp · Go (Go + 1) / [2 (1 + Go)] = 2 · Vp · Go. Therefore, the equation for Vo is as follows: Vo = Vp · 2 · Go [1 + Δ (k2 + k4 + k12−k34-2k1) / 2] = Vp · 2 · Go [1 + Δ · Vp · Go] = 2 · Go [Vp + Δ · Go · Vp ² ].

Here, a sine wave is considered as an input signal.

[0060] ^{Vp = Asinωt Vp 2 = A 2} sin 2 ωt = A 2 (1-cos2ωt) / 2 than this, Vo = 2 · Go [Vp + Δ · Go · Vp 2] = 2 · Go · A [sinωt + Δ · Go A (1-cos2ωt) / 2] cos2ωt on the right side of the above equation indicates a second harmonic.
Therefore, assuming that the second harmonic distortion factor is 2HD, 2HD = −Go · Δ · A / 2 Here, the negative sign indicates that the fundamental wave is 2ω with respect to sinωt.
This shows that the second harmonic has a phase relationship of -cos2ωt.

Also in the differential amplifier, since the nonlinear coefficient Δ is determined by the type of the resistor, the second harmonic distortion factor 2H
To control D, Go may be changed. But,
2Go is the gain of this differential amplifier. Usually, since the gain is designed to be constant, it is almost impossible to change the gain. That is, in the conventional differential amplifier, a constant second harmonic distortion rate is obtained due to the inherent nonlinear coefficient of the resistor, and it is impossible to control this.

Next, as in the case of the above-described inverting amplifier and non-inverting amplifier, in the differential amplifier, the resistors R1 and R1 are connected.
Consider a case where different types of resistors are used as the resistors R2, R3, and R4.

As shown in FIG. 14, the midpoint potential of the resistor R1 is (Vm + Vi) / 2, and the midpoint potential of the resistor R2 is (Vo + Vi).
Vi) / 2 and the midpoint potential of the resistor R3 is (Vp + Vi) /
2. Since the middle point potential of the resistor R4 is Vi / 2,
The nonlinear coefficients of R1, R2, R3, and R4 are Δ1, Δ
Assuming 2, 3, and 4, the following equation is established.

R1 = R1o [1 + Δ1 · (Vm + Vi) / 2] R2 = R2o [1 + Δ2 · (Vo + Vi) / 2] R3 = R3o [1 + Δ3 · (Vp + Vi) / 2] R4 = R4o (1 + Δ4 · Vi / 2) Difference Vm = −Vp, R3o = R1o, R
4o = R2o, and here again, Go = R2o / R1o.

Further, for the sake of simplicity, the above R1 to R4
In the expressions on the right side, Vi and Vo on the right side are as follows: Vi = Vp · R4 / (R3 + R4) = Vp · R4o / (R3o + R4o) = Vp · R2o / (R1o + R2o) = Vp · Go / (1 + Go) Vo = 2 · Go・ Substitute Vp. Then, the above equations R1 to R4 are as follows.

R1 = R1o [1 + Δ1 · (Vm + Vi) / 2] = R1o ｛1 + Δ1 · [−Vp + Vp · Go / (1 + Go)] / 2｝ = R1o ｛1−Δ1 · Vp · Go / [2 (1 + Go)] ＝= R1o (1−Δ1 · k1) where k1 = Vp / [2 (1 + Go)] R2 = R2o [1 + Δ2 · (Vo + Vi) / 2] = R2o ｛1 + Δ2 · [2 · Go · Vp + Vp · Go / (1 + Go) )] / 2｝ = R2o ｛1 + Δ2 ・ Vp ・ Go (2Go + 3) / [2 (1 + Go)]｝ = R2o (1 + Δ2 ・ k2) where k2 = Vp ・ Go (2Go + 3) / [2 (1 + Go)] = k1 Go ・ (2Go + 3) R3 = R3o [1 + Δ3３ (Vp + Vi) / 2] = R3o ｛1 + Δ3 ・ [Vp + Vp ・ Go / (1 + Go)] / 2｝ = R1o ｛1 + Δ3 ・ Vp (2Go + 1) / [2 (1 + Go)]｝ = R1o (1 + Δ3 · k3) where k3 = Vp · (2Go + 1) / [2 (1 + Go)] = k1 · (2Go + 1) R4 = R4o (1 + Δ4 · Vi / 2) = R2o ｛1 + Δ4 · Vp · Go / [2 (1 + Go)]｝ = R2o (1 + Δ4 · k4) where k4 = Vp · Go / [2 (1 + Go)] = k1 · Go The relational expression between Vo and Vp is Vo = (R2 / R1) ｛(R1 + R2) R4 · Vp / [R2 (R3 + R4)] − Vm｝ = Vp · [R4 (R1 + R2) + R2 (R3 + R4)] / [R1 (R3 + R4)] = 2 · Vp · Go [1+ (Δ1 · k1 + Δ2 · k2 + Δ4 · k4 + Δ12−Δ34) / 2] where Δ12 = (R2o · Δ2 · k2-R1o · Δ1 · k1) / (R1o + R2o) = k1 [Go^Two (2Go + 3) Δ2-Δ1] / (1 + Go) k34 = (R1o · Δ3 · k3 + R2o · Δ4 · k4) / (R1o + R2o) = (Δ3 · k3 + Go · Δ4 · k4) / (1 + Go) = (Δ3 · k1 · ( 2Go + 1) + Go · Δ4 · k1 · Go) / (1 + Go) = k1 [Δ3 · (2Go + 1) + Δ4 · Go^Two ] / (1 + Go). Therefore, Δ12−Δ34 = k1 [Go^Two ・ (2Go + 3) Δ2-Δ1-Δ3 ・ (2Go + 1) -Δ 4 ・ Go^Two ] / (1 + Go) Δ1 · k1 + Δ2 · k2 + Δ4 · k4 + Δ12−Δ34 = Δ1 · k1 + Δ2 · k1 · Go · (2Go + 3) + Δ4 · k1 · Go + k1 [Go^Two ・ (2Go + 3) Δ2-Δ1-Δ3 ・ (2Go + 1) -Δ4 ・ Go ^Two ] / (1 + Go) = k1 [Δ1 · (1 + Go) + Δ2 · Go · (2Go + 3) (1 + Go) + Δ4 · Go (1 + Go) + Go^Two ・ (2Go + 3) Δ2-Δ1-Δ3 ・ (2Go + 1) -Δ4 ・ Go^Two ] / (1 + Go) = k1 [Δ1 · Go + Δ2 · Go · (2Go + 3) (1 + 2Go) + Δ4 · Go−Δ3 · (2Go + 1)] / (1 + Go) Therefore, the equation of Vo is as follows: Vo = Vp · [R4 (R1 + R2) + R2 (R3 + R4)] / [R1 (R3 + R4)] = 2 · Vp · Go [1+ (Δ1 · k1 + Δ2 · k2 + Δ4 · k4 + Δ12−Δ34) / 2 ] = 2 · Vp · Go ｛1 + k1 [Δ1 · Go + Δ2 · Go · (2Go + 3) (1 + 2Go) + Δ4 · Go−Δ3 · (2Go + 1)] / [2 (1 + Go)]｝ = 2 · Vp · Go ｛1 + Vp [Δ1 Go + Δ2 · Go · (2Go + 3) (1 + 2Go) + Δ4 · Go−Δ3 · (2Go + 1)] / [2 (1 + Go)^Two み る Here, consider a sine wave as an input signal.

Vp = Asinωt Vp^Two = A^Twosin^Two ωt = A^Two (1−cos2ωt) / 2 From this, Vo = 2 · Vp · Go ｛1 + Vp [Δ1 · Go + Δ2 · Go · (2Go + 3) · (1 + 2Go) + Δ4 · Go−Δ3 · (2Go + 1)] / [2 (1 + Go)] ^Two = 2 · Go ｛sin ωt + A (1-cos2ωt) [Δ1 · Go + Δ2 · Go · (2Go + 3) (1 + 2Go) + Δ4 · Go−Δ3 · (2Go + 1)] / [4 (1 + Go)]^Two Ｃｏ cos2ωt on the right side of the above equation indicates the second harmonic.
Therefore, if the second harmonic distortion factor is set to 2HD, 2HD = −A [Δ1 · Go + Δ2 · Go · (2Go +
3) (1 + 2Go) + Δ4 · Go−Δ3 · (2Go +
1)] / [4 (1 + Go)]^Two 差動 In the case of this differential amplifier, as shown in Table 3 below,
The same type of resistor is used for R1 and resistor R2,
By using the same type of resistor as resistor R4, integration
Gain fluctuations due to variations in the circuit manufacturing process
The distortion can be controlled to some extent while avoiding.

[0068]

[Table 3]

However, without changing the gain,
Further, while it is possible to control a certain degree of secondary distortion while suppressing variations in gain during mass production, it is far from controlling the secondary distortion freely.

[0070]

As described above, in the related art, the use of two types of resistors can control the secondary distortion to some extent, but cannot control the secondary distortion freely. there were.

Therefore, the present invention provides a distortion control circuit which can freely set the nonlinear coefficient of the resistance within a certain range and can freely control the secondary distortion while avoiding the fluctuation of the gain. It is an object.

[0072]

In order to achieve the above object, a distortion control circuit according to the present invention comprises: a first combined resistor in which a plurality of types of resistors having different nonlinear coefficients are connected in series; Connect multiple types of resistors with different coefficients in series,
And a second combined resistor having a resistance ratio substantially equal to a ratio of each resistance of the first combined resistor, and a second combined resistor formed on an integrated circuit board. ,
According to the connection position of each resistor in the second combined resistor and the ratio of each resistor, the resistance ratio between the first and second combined resistors is made substantially constant, and the secondary distortion rate of the integrated circuit is controlled. It has a configuration.

In the distortion control circuit according to the present invention,
An operational amplifier connected between an inverting input terminal and a signal input terminal of the operational amplifier and having first and second non-linear coefficients different from each other;
And a first combined resistor connected in series between the inverting input terminal and the signal output terminal of the operational amplifier, and a ratio of the first combined resistor to the first and second resistors. And a second combined resistor in which third and fourth resistors are connected in series and have substantially the same resistance ratio.

In the distortion control circuit of the present invention,
An operational amplifier, a first combined resistor connected between the inverting input terminal of the operational amplifier and ground and having first and second resistors having different nonlinear coefficients connected in series, and an inverting input terminal of the operational amplifier. And a third output terminal connected between the first and second combined resistors, and having a resistance ratio substantially equal to the ratio of the first and second resistances of the first combined resistance. 2 combined resistors.

Further, in the distortion control circuit according to the present invention, the operational amplifier, the inverting input terminal of the operational amplifier and the first
A first combined resistor connected in series with the first and second signal resistors having different nonlinear coefficients, and
A third and a fourth resistor connected between an inverting input terminal of the operational amplifier and a signal output terminal and having a resistance ratio substantially equal to a ratio of the first and second resistors of the first combined resistor; A second combined resistor in which resistors are connected in series, and a fifth resistor and a sixth resistor which are connected between a non-inverting input terminal of the operational amplifier and a second signal input terminal and have different nonlinear coefficients are connected in series; A third combined resistor connected between the non-inverting input terminal of the operational amplifier and the ground, and the fifth combined resistor and the sixth combined resistor of the third combined resistor.
And a fourth combined resistor in which seventh and eighth resistors are connected in series and have substantially the same resistance ratio as that of the first resistor.

According to the distortion control circuit of the present invention, it is possible to offset the variation in the resistance value during mass production between the combined resistors. As a result, without changing the gain
The second-order distortion can be canceled or controlled to an arbitrary value.

[0077]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows an example in which an inverting amplifier is configured as a secondary distortion control circuit according to a first embodiment of the present invention.

That is, the inverting amplifier comprises an operational amplifier (operational amplifier) OP11 and a combined resistor (first combined resistor) R12 connected between the inverted input (-) end of the operational amplifier OP11 and the Vi input terminal. , Inverting input terminal and Vo
And a combined resistor (second combined resistor) k · R21 connected between the output terminal.

The combined resistor R12 couples two resistors R1 and R2 (first and second resistors) having different nonlinear coefficients from the Vi input terminal side to the inverting input terminal side.
And the second resistor R2 are connected in series in this order, and have a desired nonlinear coefficient.

The combined resistance k · R21 is equal to each of the resistances R1,
The resistors k and R1 (third resistors) and k and R2 (the same type as the resistors R1 and R2, which have substantially the same resistance ratio as the ratio of R2 and have k times the resistance value, respectively) Fourth resistance)
Are connected in series in the order of a third resistor k · R1 and a fourth resistor k · R2 from the inverting input terminal side to the Vo output terminal side, and have a resistance k times the combined resistance R12. It has a value.

The non-inverting input (+) terminal of the operational amplifier OP11 is grounded.

The first and second combined resistors R12, R12,
Each resistor R1, R2, k · R1, k constituting k · R21
R2 and operational amplifier OP11 are provided, for example, on an integrated circuit board. For example, the resistors R1, k
R1 is a diffusion or ion implantation resistance, the resistors R2, k · R2 are conductive thin film resistors, or the resistors R1, k · R1 are conductive thin film resistors, and the resistors R2, k · R2 are diffusion Or an ion implantation resistance.

In this case, for example, as shown in FIG. 2, the midpoint potential V1 of the resistor R1 in the combined resistor R12 is
It is given by the following equation.

V1 = [(R1 / 2 + R2) / (R1 + R2)] · V Similarly, the midpoint potential V2 of the resistor R2 is: V2 = [(R2 / 2) / (R1 + R2)] · V The nonlinear coefficient of the resistor R1 Is Δ1 and the nonlinear coefficient of the resistor R2 is Δ2, R1 = R1o ｛1 + Δ1 [(R1 / 2 + R2) / (R1
+ R2)] · V｝ R2 = R2o ｛1 + Δ2 [(R2 / 2) / (R1 + R
2)] · V｝ Here, as a first-order approximation, the resistances on the right side of the above equation are replaced by R1 → R1o and R2 → R2o, respectively, and the ratio α between the resistors R1 and R2 is R2o / R1o. = R1o ｛1 + Δ1 [(R1o / 2 + R2o) / (R1o + R2o)] · V｝ R2 = R2o ｛1 + Δ2 [(R2o / 2) / (R1o + R2o)] · V｝ R12 = R1 + R2 = R1o ｛1 + Δ1 [(R1o / 2 + R2o) / (R1o + R2o)] · V} + R2o {1 + Δ2 [(R2o / 2) / (R1o + R2o)] · V} = (R1o + R2o) (1 + Δ '· V / 2) Δ' = (Δ1 + 2 · α · Δ1 + α 2 · Δ2) / (1 + α) ^{2 From the} above two equations, it can be seen that the combined resistance R12 has a resistance value at V = 0 of R1o + R2o and a nonlinear coefficient of Δ ′. The value of Δ ′ can be changed by changing the ratio between the resistance R1 and the resistance R2, so that the nonlinear coefficient Δ1
And a non-linear coefficient Δ2.

On the other hand, for example, as shown in FIG.
1 and the position of the resistor R2 are reversed,
In the case of the combined resistance k · R21 having twice the resistance value, the resistances k · R1 and k · R2 on the right side of the following equation are also R
When replaced with 1o and R2o, the midpoint potential V2 of the resistor k · R2 becomes V2 = [(k · R2 / 2 + k · R1) / (k · R2 + k · R1)] · V = [(R2 / 2 + R1) / ( R2 + R1)] · V = [(R2o / 2 + R1o) / (R2o + R1o)] · V Similarly, the midpoint potential V1 of the resistor k · R1 is V1 = [(k · R1 / 2) / (k · R2 + k · R1) )] · V = [(R1 / 2) / (R2 + R1)] · V = [(R1o / 2) / (R2o + R1o)] · V The nonlinear coefficient of the resistor k · R1 is Δ1, and the nonlinear coefficient of the resistor k · R2 is Assuming that Δ2, k · R2 = k · R2o (1 + Δ2 · V2) = k · R2o ｛1 + Δ2 [(R2o / 2 + R1o) / (R2o + R1o)] · V｝ k · R1 = k · R1o (1 + Δ1 · V1) = k · R1o ｛1 + Δ1 [(R1o / 2) / (R2o + R1o)] · V｝ R21 = kR2 + kR1 = kR2o ｛1 + Δ2 [(R2o / 2 + R1o) / (R2o + R1o)] · V｝ + kR1o ｛1 + Δ1 [(R1o / 2) / (R2o + R1o) )] · V} from = k · (R1o + R2o) (1 + Δ '' · V / 2) Δ '' = (α 2 · Δ2 + 2 · α · Δ2 + Δ1) / (1 + α) 2 above two equations, the combined resistance k · R21 has a resistance value of k · (R1o + R2o) at V = 0 and a non-linear coefficient of Δ ″.
It turns out that it becomes. By changing the ratio between the resistances k · R1 and k · R2, the value of Δ ″ can be changed freely between the nonlinear coefficient Δ1 of the resistance k · R1 and the nonlinear coefficient Δ2 of the resistance k · R2. Can be taken.

Here, the combined resistance R12, k · R21
Consider an inverting amplifier (see FIG. 1) configured using

Since the inverting input terminal of the operational amplifier OP11 is a virtual ground point (virtual ground), FIGS.
The calculation result of the combined resistance R12, k · R21 shown in (1) can be used as it is, and the following equation is established.

Vo = −Vi · Ro / Ri = −Vi · k · R21 / R12 = −Vi · k · (R1o + R2o) (1 + Δ ″ · Vo / 2) / [(R1o + R2o) · (1 + Δ ′ · Vi /2)]=-Vi.k.(1+.DELTA.".Vo/2)/(1+.DELTA.'.Vi/2)=-Vi.k.(1+.DELTA.".Vo/2-.DELTA.'.Vi/2) Here, when Vo on the right side of the above equation is approximated by Vo = −k · Vi, Vo = −Vi · k · (1−Δ ″ · k · Vi / 2−Δ ′ · Vi / 2) = − Vi・ K · [1- (k · Δ ″ + Δ ′) Vi / 2] = − Vi · k · [1−Δ ′ ″ · Vi / 2] = − k · [Vi−Δ ′ ″ · Vi ^2/2] However, in Δ '''= k · Δ ''+Δ' above equation, the gain k of the fundamental wave ratio of the same type of resistance is (R1: k · R2: k · R1, R2), Even if the resistance value fluctuates during mass production of integrated circuits, The value of the gain k is substantially constant.

Here, a sine wave is considered as an input signal.

[0090] ^{Vi = Asinωt Vi 2 = A 2} sin 2 ωt = A 2 (1-cos2ωt) / 2 From this, Vo = -k · (Vi- Δ '''· Vi 2/2) = -k · A • [sinωt−Δ ″ ′ ”A (1−cos2ωt) / 4] 2HD = −Δ ′ ″ A / 4 = − (k · Δ ″ + Δ ′) A / 4 = −A · [(k · α ² + 2 · k · α + α ² ) Δ2 + (k + 2 · α + 1) · Δ1] / [4 · (1 + α) ² ] If α = 0, (R2 = k · R2 = 0), 2HD (α = 0) = − A · [(k + 1) · Δ1] / 4 This value is a value when only the resistors R1 and k · R1 with a nonlinear coefficient of Δ1 are used.

If α = 1 (R1o = R2o, k · R
1o = k · R2o), 2HD (α = 1) = − A · [(3 · k + 1) Δ2 + (k
+3) · Δ1] / 16α = ∞ (R1 = k · R1
= 0), 2HD (α = ∞) = − A · [(k + 1) · Δ2] / 4 This value is a value when only the resistors R2 and k · R2 with a nonlinear coefficient of Δ2 are used.

As described above, according to the inverting amplifier of the present invention, by changing the ratio α of the resistors R2 and R1 from 0 to ∞ without changing the gain k, the secondary distortion is reduced to 2HD (α
= 0) to 2HD (α = ∞).

Further, two types of resistors (R1, R2 or k
(R1, k · R2) can also avoid the adverse effect of gain variation during mass production of integrated circuits.

As described above, the variation in the resistance value during mass production can be offset among the combined resistors.

That is, on the integrated circuit board, first and second resistors having different nonlinear coefficients are connected in series to form a combined resistor having an arbitrary nonlinear coefficient within a certain range. The inverting amplifier is configured by using another combined resistor configured with a ratio. As a result, by using two types of resistors,
It is possible to freely set the nonlinear coefficient of the resistance within a certain range while suppressing the gain variation during mass production of the integrated circuit. Therefore, the secondary distortion can be canceled or the secondary distortion can be controlled to an arbitrary value without changing the gain.

In the above-described first embodiment of the present invention, the case where the ratio α of the resistance R2 and the resistance R1 is changed from 0 to ∞ so that the secondary distortion can be freely controlled. Although explained, the resistance R2 is not limited to this.
The secondary distortion can be controlled by changing the position of the two types of resistors (R1, R2 or kR1, kR2) in addition to changing the ratio α between the resistance R1 and the resistor R1. .

FIG. 4 shows the above-described inverting amplifier (see FIG. 1).
Is an example in which the positions of the resistors R1 and R2 are interchanged.

That is, the inverting amplifier comprises an operational amplifier OP11, and an inverting input terminal of the operational amplifier OP11 and V
between the i input terminal and the combined resistor R12.
A combined resistor (first combined resistor) R12 ′ in which the positions of R1 and R2 are connected in reverse, and a combined resistor (second combined resistor) k · R21 connected between the inverting input terminal and the Vo output terminal. It is composed of

The combined resistor R12 'is connected to two resistors R1 and R2 (first and second resistors) having different nonlinear coefficients from the inverting input terminal side toward the Vi input terminal side by a first resistor. R1 and the second resistor R2 are connected in series in this order, and have a desired nonlinear coefficient.

The combined resistance k · R21 is equal to the resistances R1,
The resistors k and R1 (third resistors) and k and R2 (the same type as the resistors R1 and R2, which have substantially the same resistance ratio as the ratio of R2 and have k times the resistance value, respectively) Fourth resistance)
Are connected in series from the inverting input terminal side to the Vo output terminal side in the order of a third resistor k · R1 and a fourth resistor k · R2, and are k times as large as the combined resistor R12 ′. It is configured to have a resistance value.

The non-inverting input terminal of the operational amplifier OP11 is grounded.

Similarly, the first and second combined resistors R1
2 ′, k · R21, the respective resistors R1, R2, k · R
1, k · R2 and operational amplifier OP11 are, for example,
It is provided on an integrated circuit substrate. For example, the resistor R
1, k · R1 is a diffusion or ion implantation resistance, the resistors R2, k · R2 are conductive thin film resistors, or the resistors R1, k · R1 are conductive thin film resistors, and the resistors R2, k R2 is the diffusion or ion implantation resistance.

In this case, the combined resistance R12 'obtained by replacing the resistances R1 and R2 is as follows: R12' = R2o ｛1 + Δ2 [(R2o / 2 + R1o) / (R1o + R2o)] · Vi｝ + R1o ｛1 + Δ1 [(R1o / 2) / (R1o + R2o)] · Vi｝ = (R1o + R2o) (1 + Δ · Vi / 2) Δ = (Δ1 + 2 · α · Δ2 + α ² · Δ2) / (1 + α) ^{2 When} the relationship between Vo and Vi is calculated again with this value, Vo = −Vi · Ro / Ri = −Vi · k · R21 / R12 ′ = − Vi · k · (R1o + R2o) (1 + Δ ″ · Vo / 2) / [(R1o + R2o) · (1 + Δ · Vi / 2) ] = − Vi · k · (1 + Δ ″ · Vo / 2) / (1 + Δ · Vi / 2) = − Vi · k · (1 + Δ ″ · Vo / 2−Δ · Vi / 2) Is approximated by Vo = −k · Vi, Vo = −Vi · K · (1-Δ '' · k · Vi / 2-Δ · Vi / 2) = -Vi · k · [1-(k · Δ "+ Δ) Vi / 2] = -Vi · k · [ 1-Δ '''· Vi / 2] = -k · [Vi-Δ''' · Vi 2/2] However, Δ '''= k · Δ''+ Δ in the equation, the gain k to the fundamental Is the ratio of the same type of resistors (R1: k · R1, R2: k · R2), and the gain k is substantially constant even if the resistance value varies during mass production of the integrated circuit.

Here, a sine wave is considered as an input signal.

[0105] ^{Vi = Asinωt Vi 2 = A 2} sin 2 ωt = A 2 (1-cos2ωt) / 2 From this, Vo = -k · [Vi- Δ '''· Vi 2/2] = -k · A · [sinωt-Δ ''' · A (1-cos2ωt) / 4] 2HD = -Δ''' A / 4 = - (k · (α 2 · Δ2 + 2 · α · Δ2 + Δ1) + (Δ1 + 2 · α · Δ 2 + α ² · Δ2)) A / [4 · (1 + α) ² ] = − A (k + 1) [α (α + 2) Δ2 + Δ1] / [4 · (1 + α) ² ] If α = 0, R2 = k · R2 = 0), 2HD (α = 0) = − A · [(k + 1) · Δ1] / 4 This value is a value when only the resistors R1 and k · R1 with a nonlinear coefficient of Δ1 are used.

If α = 1, (R1o = R2o, k · R
1o = k · R2o) 2HD (α = 1) = − A · (k + 1) [(3 · Δ2 + Δ
1)] / 16 This value is the value of the inverting amplifier shown in FIG.
k + 1) Δ2 + (k + 3) Δ1] / 16). That is, it is understood that the secondary distortion of the inverting amplifier can be controlled by changing the positions of the two types of resistors R1 and R2.

Similarly, in the inverting amplifier shown in FIG. 1, the value of the second harmonic distortion factor 2HD (α = 1) is changed even if the positions of the resistors kR1 and kR2 are switched. be able to.

Further, when α = ∞, (R1 = k · R1
= 0), 2HD (α = ∞) = − A · [(k + 1) · Δ2] / 4 This value is a value when only the resistors R2 and k · R2 with a nonlinear coefficient of Δ2 are used.

As described above, according to the inverting amplifier of the present invention, in addition to changing the ratio α of the resistors R2 and R1 from 0 to ∞ without changing the gain k, two types of resistors (R1, R2 Alternatively, it is also possible to control the secondary distortion by changing the positional relationship of k · R1, k · R2).

In this case as well, it is possible to avoid the problem of gain variation during mass production of integrated circuits due to the use of two types of resistors (R1, R2 or k · R1, k · R2).

Further, the present invention is not limited to the case where an inverting amplifier is formed, and for example, a non-inverting amplifier can be formed. (Second Embodiment) FIG. 5 shows a second embodiment of the present invention, in which the above-described resistor R12 (see FIG. 2) and resistor k ·
This is an example in which a non-inverting amplifier is configured using R21 (see FIG. 3).

That is, the non-inverting amplifier includes an operational amplifier OP12 and a combined resistor (first combined resistor) R connected between the inverting input terminal of the operational amplifier OP12 and the ground.
12 and a combined resistor (second combined resistor) k.R21 connected between the inverting input terminal and the Vo output terminal.

The combined resistor R12 couples two resistors R1 and R2 (first and second resistors) having different nonlinear coefficients from the inverting input terminal side to the ground side with the first resistor R1.
The first and second resistors R2 are connected in series in this order, and have a desired nonlinear coefficient.

The combined resistance k · R21 is equal to the resistance R1,
The resistors k · R1 (third resistor) and k · R2 (fourth resistor) having substantially the same resistance ratio as R2 and having the same k-fold resistance value as the resistors R1 and R2. Resistance),
From the inverting input terminal side to the Vo output terminal side,
The third resistor k · R1 and the fourth resistor k · R2 are connected in series in this order, and have a resistance value k times the combined resistor R12.

The non-inverting input terminal of the operational amplifier OP12 is connected to the Vi input terminal.

Similarly, the first and second combined resistors R1
2, k · R21, each resistor R1, R2, k · R
1, k · R2 and operational amplifier OP12 are, for example,
It is provided on an integrated circuit substrate. For example, the resistor R
1, k · R1 is a diffusion or ion implantation resistance, the resistors R2, k · R2 are conductive thin film resistors, or the resistors R1, k · R1 are conductive thin film resistors, and the resistors R2, k R2 is the diffusion or ion implantation resistance.

In this case, for the combined resistor R12, the example of the first embodiment described above (see FIGS. 1 and 4) can be used as it is, so that R12 = (R1o + R2o) (1 + Δ ′ · Vi / 2) Δ ′ = (Δ1 + 2 · α · Δ1 + α ² · Δ2) / (1+
α) ² where α = R2o / R1o The combined resistor k · R21 needs to be obtained from the midpoint potential of each resistor R1, R2, k · R1, k · R2 because one end is not grounded.

The midpoint potential V2 of the resistor R1 is as follows: V1 = [(kR2 + kR1 / 2) Vi + (kR1 / 2) Vo] / (kR2 + kR1) = [(R2o + R1o / 2) Vi + (R1o / 2) Vo] / (R2o + R1o) Similarly, the midpoint potential V2 of the resistor R2 can be calculated as follows: V2 = [(kR2 / 2) Vi + (kR1 + kR2 / 2) Vo] / (k. R2 + kR1) = [(R2o / 2) Vi + (R1o + R2o / 2) Vo] / (R2o + R1o) Here, Vo = (1 + k) approximately on the right side of the above equation.
Using Vi and setting α = R2o / R1o, V1 = [(R2o + R1o / 2) + (R1o / 2) (1 + k)] · Vi / (R2o + R1o) = [2 · (α + 1) + k] Vi / [ 2 · (α + 1)] V2 = [(R2o / 2) + (R1o + R2o / 2) (1 + k)] · Vi / (R2o + R1o) = [(k + 2) · α + 2 · (1 + k)] Vi / [2 · (α + 1) )] Assuming that the nonlinear coefficient of the resistor k · R1 is Δ1 and the nonlinear coefficient of the resistor k · R2 is Δ2, k · R2 = k · R2o (1 + Δ2 · V2) = k · R2o ｛1 + Δ2 [(k + 2) · α + 2 · ( 1 + k)] · Vi / [2 · (α + 1)]｝ k · R1 = k · R1o (1 + Δ1 · V1) = k · R1o ｛1 + Δ1 [2 · (α + 1) + k] · Vi / [2 · (α + 1) ]｝ K · R21 = k · R2 + k · R1 = k · R2o (1 Δ2V2) + kR1o (1 + Δ1V1) = {kR2o + kR1o} + ΔkR2oΔ2 [(k + 2) α + 2 (1 + k)] + kR1oΔ1 [2 (α + 1) + k ]｝ / Vi / [2 · (α + 1)] = k · (R1o + R2o) (1 + Δ ″ · Vi / 2) Δ ″ = {k · R2o · Δ2 [(k + 2) · α + 2 · (1 + k)] + k · R1 o · Δ1 [2 · (α + 1) + k]｝ / [(α + 1) · k · (R1o + R2o)] = {α · Δ2 [(k + 2) · α + 2 · (1 + k)] + Δ1 [2 · (α + 1) + k] Since the inverting input terminal of the｝ / (α + 1) ² operational amplifier OP12 has the same potential as the non-inverting input terminal, the following equation holds.

Vo = Vi · (R12 + k · R21) / R12 = Vi · (1 + k · R21 / R12) = Vi + Vi · k · (R1o + R2o) (1 + Δ ″ · Vi / 2) / [(R1o + R2o) (1 + Δ ′) Vi / 2)] = Vi + Vi.k. (1 + .DELTA. ". Vi / 2) / (1 + .DELTA. '. Vi / 2) = Vi + Vi.k. (1 + .DELTA.". Vi / 2-.DELTA.'. Vi / 2) = Vi + Vi · k · [ 1+ (Δ '' - Δ ') · Vi / 2] = (1 + k) Vi + k · (Δ''-Δ') · Vi 2/2 = (1 + k) {Vi + k · (Δ '' −Δ ′) · Vi ² / [2 · (1 + k)] 正弦 Here, a sine wave is considered as an input signal.

Vi = Asinωt Vi^Two = A^Two sin^Two ωt = A^Two(1−cos2ωt) / 2 From this, Vo = (1 + k) · A · {sinωt + k · (Δ ″ −Δ ′) · A · (1-cos2ωt) / [4 · (1 + k)]} 2HD = − k · (Δ ″ −Δ ′) · A / [4 · (1 + k)] Δ ″ −Δ ′ = ｛α · Δ2 [(k + 2) · α + 2 · (1 + k)] + Δ1 [2 · (α + 1) + k ]-(Δ1 + 2 · α · Δ1 + α^Two ・ Δ2)｝ / (1 + α)^Two = ｛Α^Two・ Δ2 ・ (k + 1) + α ・ Δ2 ・ 2 ・ (1 + k) + Δ1 ・ (k + 1) （/ (1 + α)^Two 2HD = -k · A · ｛α^Two ・ Δ2 + 2 ・ α ・ Δ2 + Δ1２ / [4 ・ (1 + α) ^Two Assuming that α = 0 (R2 = k · R2 = 0), 2HD (α = 0) = − k · A · Δ1 / 4 This value is only for the resistors R1 and k · R1 having a nonlinear coefficient of Δ1.
This is the value when configured with.

When α = 1, (R1o = R2o, k · R
1o = k · R2o), 2HD (α = 1) = − k · A · [3 · Δ2 + Δ1] / 1
6 When α = α (R1 = k · R1 = 0), 2HD (α = ∞) = − k · A · Δ2 / 4 This value is composed of only resistors R2 and k · R2 with a nonlinear coefficient of Δ2. The value of the case.

As described above, according to the non-inverting amplifier of the present invention, by changing the ratio α of the resistors R2 and R1 from 0 to ∞ without changing the gain (1 + k), the secondary distortion is reduced by 2H.
It can be controlled freely within the range of D (α = 0) to 2HD (α = ∞).

Also in this case, it is possible to avoid the problem of gain variation during mass production of integrated circuits due to the use of two types of resistors (R1, R2 or k · R1, k · R2).

Also, as in the case of the inverting amplifier described above,
Two types of resistors (R1, R2 or kR1, kR2)
The secondary distortion can be controlled by changing the positional relationship of. Also in this case, it is possible to avoid the problem of gain variation during mass production of the integrated circuit due to the use of two types of resistors.

The present invention is not limited to the case where an inverting amplifier or a non-inverting amplifier is formed. For example, a differential amplifier can be formed. (Third Embodiment) FIG. 6 shows a third embodiment of the present invention, in which the above-described resistor R12 (see FIG. 2) and resistor k ·
This is an example in which a differential amplifier is configured using R21 (see FIG. 3).

That is, this differential amplifier comprises an operational amplifier OP13 and an inverting input terminal of the operational amplifier OP13.
A combined resistor (first combined resistor) R12 connected between the Vi input terminal (first signal input terminal) and a combined resistor (second combined resistor) connected between the inverting input terminal and the Vo output terminal. (Combined resistor) k · R21, and a combined resistor (third resistor) connected between the non-inverting input terminal and the Vi input terminal (second signal input terminal).
R34) and a combined resistance (fourth combined resistance) kR43 connected between the non-inverting input terminal and the ground.

The combined resistance R12 has different nonlinear coefficients Δ
The two resistors R1 and R2 (first and second resistors) having the first and second resistances R1 and R2 from the -Vi input terminal side toward the inverting input terminal side are connected to the first resistor R1 and the second resistor R2. They are connected in series in order and have a desired nonlinear coefficient.

The combined resistance k · R21 is equal to each of the resistances R1,
The resistors k and R1 (third resistors) and k and R2 (the same type as the resistors R1 and R2, which have substantially the same resistance ratio as the ratio of R2 and have k times the resistance value, respectively) Fourth resistance)
Are connected in series in the order of a third resistor k · R1 and a fourth resistor k · R2 from the inverting input terminal side to the Vo output terminal side, and have a resistance k times the combined resistance R12. It has a value.

The combined resistance R34 has different nonlinear coefficients Δ
The three resistors R3 and R4 (fifth and sixth resistors) having the third and third resistances of the fifth resistor R3 and the sixth resistor R4 from the Vi input terminal side to the non-inverting input terminal side. They are connected in series in order and have a desired nonlinear coefficient.

The combined resistance k · R43 is equal to the resistances R3 and R3.
The resistors k.R3 (seventh resistor) and k.R4 (the same type as the resistors R3 and R4, which have substantially the same resistance ratio as the ratio of R4 and have a resistance value of k times, respectively) Eighth resistance)
Are connected in series from the ground side to the non-inverting input end in the order of a seventh resistor k · R3 and an eighth resistor k · R4, and have a resistance value k times that of the combined resistor R34. Is configured.

Similarly, each of the resistors R1, R2, k · R1, k · R2, R3 constituting the first, second, third, and fourth combined resistors R12, k · R21, R34, k · R43. , R
4, k · R3, k · R4 and operational amplifier OP13
For example, it is provided on an integrated circuit substrate. For example, the resistors R1, k · R1 are diffusion or ion implantation resistors, the resistors R2, k · R2 are conductive thin film resistors, or the resistors R1, k · R1 are conductive thin film resistors, The resistors R2, k.R2 are diffusion or ion implantation resistors. Further, for example, the resistors R3, k · R3 are diffusion or ion implantation resistors, and the resistors R4, k · R4
Is a conductive thin film resistor, or the resistor R3, k ·
R3 is a conductive thin film resistor, and the resistors R4, k and R4 are diffusion or ion implantation resistors.

In this case, the voltage V at the non-inverting (forward) input terminal and the inverting input terminal is expressed as follows: V = Vi · K · R43 / (R34 + k · R43) Therefore, the relation between Vo and Vi is as follows: Vo = kR21 (V + Vi) / R12 + V = Vi2k [R43 (R12 + kR21) + R21 (R34 + kR43)] / [2R12 (R34 + kR43)] Becomes

Here, each resistor R1, R2, k · R1, k
-R2, R3, R4, k-R3, k-R4 are represented as follows.

R1 = R10 (1 + Δ1 · V1) R2 = R20 (1 + Δ2 · V2) k · R1 = k · R10 (1 + Δ1 · Vk1) k · R2 = k · R20 (1 + Δ2 · Vk2) R3 = R10 (1 + Δ3 · V3) ) R4 = R20 (1 + Δ4 · V4) k · R3 = k · R10 (1 + Δ3 · Vk3) k · R4 = k · R20 (1 + Δ4 · Vk4) From this, the combined resistor R12 is R12 = R1 + R2 = (R10 + R20) (1 + Δ12) .DELTA.12 = [(. DELTA.1.V1 + .alpha..DELTA.2.V2) / (1 + .alpha.)]. Multidot. (2 / Vi) where .alpha. = R20 / R10.

When calculating the midpoint potentials V1 and V2, V1 = − ｛(1 + 2 · α · k + 2 · α) / [(1 + α)
(1 + k)]｝ · (Vi / 2) V2 = {(2 · k−α) / [(1 + α) (1 + k)]}
· (Vi / 2) When this is substituted into the above equation of Δ12, Δ12 = ｛[-Δ1 (1 + 2 · α · k + 2 · α) + α ·
Δ2 (2 · k-α)] / [(1 + α)^Two(1 + k)]｝ Meanwhile, the combined resistance R34 is as follows: R34 = R3 + R4 = (R10 + R20) (1 + Δ34 · Vi / 2) Δ34 = [(Δ3 · V3 + α · Δ4 · V4) / (1+
α)] · (2 / Vi) When the midpoint potentials V3 and V4 are calculated, V3 = ｛[k + (1 + α) (1 + k)] / [(1 + α)
(1 + k)]｝ · (Vi / 2) V4 = ｛[(2 + α) k + α (1 + k)] / [(1+
α) (1 + k)]｝ · (Vi / 2) When this is substituted into the above expression of Δ34, Δ34 = ｛Δ3 [k + (1 + α) (1 + k)] + α · Δ
4 [(2 + α) k + α (1 + k)]｝ / [(1 + α)^Two 
(1 + k)] Also, the combined resistance k · R21 is k · R21 = k · (R10 + R20) (1 + Δ21 · V
i / 2) Δ21 = [(Δ1 · Vk1 + α · Δ2 · Vk2) / (1
+ Α)] · (2 / Vi) When calculating the midpoint potentials Vk1 and Vk2, Vk1 = ｛[k + (1 + α) (1 + k)] / [(1+
α) (1 + k)]｝ · (Vi / 2) Vk2 = ｛[(2 + α) k + α (1 + k)] / [(1+
α) (1 + k)]｝ · (Vi / 2) By substituting this into the above equation of Δ21, Δ21 = ｛Δ1 [2k · (1 + k) + (1 + 2 · α) +
k] + α · Δ2 [2 (2 + α) · (1 + k) k + α ·
k]｝ / [(1 + α)^Two(1 + k)] Also, the combined resistance k · R43 is k · R43 = k · (R10 + R20) (1 + Δ43 · V
i / 2) Δ43 = [(Δ3 · Vk3 + α · Δ4 · Vk4) / (1
+ Α)] · (2 / Vi) When calculating the midpoint potentials Vk3 and Vk4, Vk3 = {k / [(1 + α) (1 + k)]} · (Vi /
2) Vk4 = {(2 + α) k / [(1 + α) (1 + k)]}
· (Vi / 2) By substituting this into the formula of Δ43, Δ43 = {Δ3 · k + α · Δ4 (2 + α) k} / [(1
+ Α)^Two (1 + k)] of each combined resistor R12, R34, k · R21, k · R43
Substituting the calculation formula into the relational expression of Vo and Vi, Vo = Vi · 2 · k [R43 (R12 + k · R21) + R21 (R34 + k · R43)] / [2 · R12 (R34 + k · R43)] = 2 · k Vi ｛1 + [(2k + 1) (Δ21−Δ12) + (Δ43−Δ34)] · Vi / [4 (k + 1)]｝ = 2 · k ｛Vi + [(2k + 1) (Δ21−Δ12) + (Δ43− Δ34)] · Vi^Two / [4 (k + 1)]｝ = 2 · k (Vi + Δ · Vi^TwoHere, Δ = [(2k + 1) (Δ21−Δ12) + (Δ43−Δ34)] / [4 (k + 1)] Δ21−Δ12 = ｛Δ1 [2k · (1 + k) + (1 + 2 · α) k] + Α · Δ2 · [2 (2 + α) · (1 + k) k + α · k]｝ / [(1 + α)^Two (1 + k)] − ｛[− Δ1 (1 + 2 · α · k + 2 · α) + α · Δ2 (2 · k−α)] / [(1 + α)^Two (1 + k)]｝ = ｛Δ1 [2k · (1 + k) + (1 + 2 · α) k] + α · Δ2 · [2 (2 + α) · (1 + k) k + α · k] + Δ1 (1 + 2 · α · k + 2 · α) − α · Δ2 (2 · k-α)]｝ / [(1 + α)^Two(1 + k)] = ｛Δ1 [2 · k · (1 + k) + (1 + 2 · α) k + (1 + 2 · α · k + 2 · α)] + α · Δ2 · [2 (2 + α) · (1 + k) k + α · k− ( 2 · k-α)]｝ / [(1 + α)^Two(1 + k)] = ｛Δ1 [2k^Two + 3k + 1 + 4 · α · k + 2 · α] + α · Δ2 · [2 · k + 4 · k^Two + 3 · α · k + 2 · α · k^Two + Α]｝ / [(1 + α)^Two (1 + k)] = (1 + 2 · k) {Δ1 (2 · α + k + 1) + α · Δ2 · [2 · k + α (k + 1)]} / [(1 + α)^Two (1 + k)] Δ43−Δ34 = {Δ3 · k · + α · Δ4 (2 + α) k−Δ3 [k + (1 + α) · (1 + k)] − α · Δ4 [(2 + α) k + α (1 + k)]} / [(1 + α ) ^Two (1 + k)] = − ｛Δ3 · (α + 1) + α^Two ・ Δ4｝ / (1 + α)^Two Δ = [(2k + 1) (Δ21−Δ12) + (Δ43−Δ34)] / [4 (k + 1)] = ｛(2k + 1)^Two[Δ1 (2 · α + k + 1) + α · Δ2 · (2 · k + α · k + α)] − (1 + k) [Δ3 · (α + 1) + α^Two ・ Δ4]｝ / [4 (k + 1) ^Two (1 + α)^Two Here, a sine wave is considered as an input signal.

[0136] ^{Vi = Asinωt Vi 2 = A 2} sin 2 ωt = A 2 (1-cos2ωt) / 2 than this, Vo = 2 · k (Vi + Δ · Vi 2) = 2 · k · A (sinωt + Δ · A (1 −cos2ωt) / 2) 2HD = −Δ · A / 2 Since the expression of Δ is quite complicated, here, when k = 1 is considered, Δ (k = 1) = ｛9 · [Δ1 (2 · α + 2) + α · Δ2 · (2 + 2 · α )] - 2 · [Δ3 · (α + 1) + α 2 · Δ4]} / [16 · (1 + α) 2] = {18 · (1 + α) (Δ1 + α · Δ2) -2 · [Δ3 · (Α + 1) + α ² · Δ4]｝ / [16 · (1 + α) ² ] Further, for α = 0, 1, ∞, when Δ is calculated, Δ (k = 1, α = 0) = (9 · Δ1 −Δ3) / 8 Δ (k = 1, α = 1) = [18 (Δ1 + Δ2) −2 · Δ
3−Δ4] / 32 Δ (k = 1, α = ∞) = (9 · Δ2−Δ4) / 8 Therefore, 2HD (k = 1, α = 0) = − A · (9 · Δ1−Δ3)
/ 16 2HD (k = 1, α = 1) = − A · [18 (Δ1 + Δ
2) −2 · Δ3-Δ4] / 64 2HD (k = 1, α = ∞) = − A · (9 · Δ2-Δ4)
/ 16 Here, assuming that R1 and R3 and R2 and R4 are the same type of resistor, respectively, Δ1 = Δ3 Δ2 = Δ4 At this time, 2HD is 2HD (k = 1, α = 0) = − A · (9 · Δ1−Δ3) / 16 = −A · 8 · Δ1 / 16 = −A · Δ1 / 2 2HD (k = 1, α = 1) = − A · [18 (Δ1 + Δ2) −2 · Δ3−Δ4 ] / 64 = −A · [16 · Δ1 + 17 · Δ2] / 64 2HD (k = 1, α = ∞) = − A · (9 · Δ2−Δ4) / 16 = −A · 8 · Δ2 / 16 = − A · Δ2 / 2 Accordingly, the 2HD can freely control the secondary distortion by changing the ratio α in the range of −A · Δ1 / 2 to −A · Δ2 / 2.

Next, when R1 and R4 and R2 and R3 are the same type of resistor, respectively, Δ1 = Δ4 Δ2 = Δ3 At this time, 2HD becomes 2HD (k = 1, α = 0) = − A · (9 · Δ1-Δ3) / 16 = -A · (9 · Δ1-Δ2) / 16 2HD (k = 1, α = 1) = -A · [18 (Δ1 + Δ2)-2 · Δ3-Δ4] / 64 = −A · [17 · Δ1 + 16 · Δ2] / 64 2HD (k = 1, α = ∞) = − A · (9 · Δ2−Δ4) / 16 = −A · (9 · Δ2−Δ1) / 16 Therefore, in this case, 2HD is -A · (9 · Δ1−Δ
2) The secondary distortion can be freely controlled by changing α in the range of / 16 to −A · (9 · Δ2−Δ1) / 16.

As described above, according to the differential amplifier of the present invention, the resistance R20 and the resistance R1 can be changed without changing the gain k.
By changing the ratio α of 0 from 0 to ∞, the secondary distortion is reduced to 2HD
It can be controlled freely within the range of (α = 0) to 2HD (α = ∞).

Also in this case, two types of resistors (R1, R2 or kR1, kR2 or R3, R4 or kR
3, k · R4), it is possible to avoid the adverse effect of gain variation during mass production of integrated circuits.

As in the case of the inverting amplifier described above, two types of resistors (R1, R2 or k · R1, k ·
By changing the positional relationship of R2 or R3, R4 or kR3, kR4), it is also possible to control the secondary distortion. Also in this case, two kinds of resistors (R1, R2 or kR1, kR2 or R3, R4 or kR3,
By using (kR4), it is possible to avoid the adverse effect of gain variation during mass production of integrated circuits.

Further, in each of the above embodiments,
The case where the distortion component of each operational amplifier is controlled has been described. However, the present invention can be applied to, for example, control of an integrated circuit that generates a constant secondary distortion in total of input and output. (Fourth Embodiment) FIG. 7 shows a fourth embodiment of the present invention, in which the present invention is applied to control of an integrated circuit that generates a constant second-order distortion in total input and output. is there.

That is, by incorporating the secondary distortion control circuit 11 according to the present invention in the subsequent stage of the integrated circuit (for example, an amplifier) 10 which generates a constant secondary distortion in total of input and output, Distortion can be canceled.

At this time, since no special element is used, the cost does not increase, and the gain of the operational amplifier is determined by the ratio of the same type of resistance, so that the gain of the operational amplifier varies during mass production of the integrated circuit. No problems occur.

Of course, various modifications can be made without departing from the scope of the present invention.

[0145]

As described above, according to the present invention, the nonlinear coefficient of the resistance can be freely set within a certain range,
A distortion control circuit capable of freely controlling the secondary distortion while avoiding a change in gain can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a secondary distortion control circuit according to a first embodiment of the present invention, taking an inverting amplifier as an example.

FIG. 2 is a schematic diagram showing a configuration example of a combined resistor formed by connecting two types of resistors having different nonlinear coefficients in series.

FIG. 3 is a schematic diagram showing another configuration example of a combined resistor formed by connecting two types of resistors having different nonlinear coefficients in series.

FIG. 4 is a schematic diagram showing another configuration example of the inverting amplifier.

FIG. 5 is a schematic diagram illustrating a configuration of a secondary distortion control circuit according to a second embodiment of the present invention, taking a non-inverting amplifier as an example;

FIG. 6 is a schematic diagram illustrating a configuration of a secondary distortion control circuit according to a third embodiment of the present invention, taking a differential amplifier as an example.

FIG. 7 is a schematic diagram showing an example in which the present invention is applied to control of an integrated circuit that generates a constant secondary distortion in total of input and output according to a fourth embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view showing a configuration example of a diffusion resistance (or an ion implantation resistance) for explaining a conventional technique and its problems.

FIG. 9 is a schematic sectional view showing a configuration example of a conductive thin film resistor.

FIG. 10 is a schematic diagram for explaining voltage dependency of a diffusion resistance (or an ion implantation resistance).

FIG. 11 is a schematic diagram showing a nonlinear resistance model of a combined resistance.

FIG. 12 is a schematic diagram showing an example in which a conventional inverting amplifier is formed using a nonlinear resistor.

FIG. 13 is a schematic diagram showing an example in which a conventional non-inverting amplifier is formed using a nonlinear resistor.

FIG. 14 is a schematic diagram showing an example in which a differential amplifier is formed using a conventional nonlinear resistor.

[Explanation of symbols]

Reference Signs List 10 integrated circuit 11 secondary distortion control circuit OP11, OP12, OP13 operational amplifier R1, R2, R3, R4, kR1, kR2, kR
3, k · R4 ... resistance R12, R12 ', k · R21, R34, k · R43 ...
Combined resistance Vi, -Vi ... input terminal Vo ... output terminal

Claims (11)

[Claims] 1. A first combined resistance in which a plurality of types of resistors having different non-linear coefficients are connected in series, and a plurality of types of resistors having different non-linear coefficients are connected in series, and their resistance ratios are equal to the first resistance. A second combined resistor having at least the same resistance ratio as the ratio of each of the combined resistors, and a connection between the first and second combined resistors formed on the integrated circuit board. A distortion control circuit, wherein a resistance ratio between the first and second combined resistances is made substantially constant according to a position and a ratio of each resistance, and a secondary distortion factor of the integrated circuit is controlled. 2. The distortion control circuit according to claim 1, wherein the integrated circuit is an amplifier that generates a constant second-order distortion in total of input and output. 3. The apparatus according to claim 1, further comprising an operational amplifier to which said first and second combined resistors are connected.
4. The distortion control circuit according to 1. 4. The distortion control circuit according to claim 1, wherein said integrated circuit is an operational amplifier to which said first and second combined resistors are connected. 5. An operational amplifier, a first combined resistor connected between an inverting input terminal and a signal input terminal of the operational amplifier, and a first and a second resistor having different nonlinear coefficients connected in series; A third and a fourth resistor connected between an inverting input terminal of the operational amplifier and a signal output terminal and having a resistance ratio substantially equal to a ratio of the first and second resistors of the first combined resistor; A distortion control circuit comprising: a second combined resistor in which resistors are connected in series. 6. The distortion control circuit according to claim 5, wherein a non-inverting input terminal of the operational amplifier is grounded. 7. An operational amplifier connected between an inverting input terminal of the operational amplifier and ground,
A first combined resistor in which first and second resistors having different nonlinear coefficients are connected in series; and a first combined resistor connected between an inverting input terminal and a signal output terminal of the operational amplifier, A distortion control circuit, comprising: a second combined resistor having a resistance ratio substantially equal to the ratio of the first and second resistors, the second combined resistor having third and fourth resistors connected in series. 8. The distortion control circuit according to claim 7, wherein a non-inverting input terminal of the operational amplifier is connected to a signal input terminal. 9. One of the first and second resistors of the first combined resistor is a diffusion or ion implantation resistor, and the other of the first and second resistors is a conductive thin film. One of the third and fourth resistors of the second combined resistor is a diffusion or ion implantation resistor, and the other of the third and fourth resistors is a conductive thin film resistor. The distortion control circuit according to claim 5, wherein: 10. A first composite circuit comprising an operational amplifier connected between an inverting input terminal of the operational amplifier and a first signal input terminal and having first and second resistors having different nonlinear coefficients connected in series. A third resistor connected between the inverting input terminal and the signal output terminal of the operational amplifier and having a resistance ratio substantially equal to the ratio of the first and second resistors of the first combined resistor; A second combined resistor having a fourth resistor connected in series, and a fifth resistor and a sixth resistor connected between a non-inverting input terminal of the operational amplifier and a second signal input terminal and having different nonlinear coefficients. A third combined resistor connected in series, a resistor connected between the non-inverting input terminal of the operational amplifier and ground, and having a resistance substantially equal to the ratio of the fifth and sixth resistors of the third combined resistor. And a fourth combined resistor having a ratio of a seventh and an eighth resistor connected in series. Distortion control circuit. 11. One of the first and second resistors of the first combined resistor is a diffusion or ion implantation resistor, and the other of the first and second resistors is a conductive thin film. One of the third and fourth resistors of the second combined resistor is a diffusion or ion implantation resistor, and the other of the third and fourth resistors is a conductive thin film resistor. Wherein one of the fifth and sixth resistors of the third combined resistor is a diffusion or ion implantation resistor, and the other of the fifth and sixth resistors is a conductive thin film resistor. And one of the seventh and eighth resistors of the fourth combined resistor is a diffusion or ion implantation resistor, and one of the seventh and eighth resistors is The distortion control circuit according to claim 10, wherein the other is a conductive thin film resistor.