JPH08125460A - Inverting amplifier circuit - Google Patents

Abstract

PURPOSE: To realize the inverting amplifier circuit in which output distortion of an inverting amplifier is almost eliminated due to the effect of a resistance change in a voltage dependent resistor. CONSTITUTION: In the inverting amplifier circuit formed by forming an inverting amplifier 1 and a voltage dependent resistor in an LSI, a 1st resistor R11 with a power supply potential VD at its back gate voltage and a 2nd resistor R12 with a ground potential GND at its back gate voltage are connected in series and connected to a noninverting input terminal (+) of the inverting amplifier 1 or an inverting input terminal (-) as a reference resistor, and a 3rd resistor R13 with a power supply potential VD at its back gate voltage and a 4th resistor R14 with a ground potential GND at its back gate voltage are connected in series and connected between a connecting point of the 1st and 2nd resistors R11, R12 connected in series and an output terminal of the inverting amplifier 1 as a feedback resistor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverting amplifier circuit formed on an LSI. Although the inverting amplifier circuit configured on the LSI is an analog IC, it can be used easily like a single transistor, and is therefore widely used in electronic circuits of electronic equipment products.

When such an inverting amplifier circuit is formed by LSI semiconductor technology, the resistor used in the inverting amplifier circuit becomes a voltage-dependent type whose resistance value changes depending on the voltage across the resistor, resulting in inverting amplification. This will adversely affect the input / output characteristics of the circuit. Therefore, there is a demand for an inverting amplifier circuit that can eliminate such drawbacks.

[0003]

2. Description of the Related Art FIG. 7 shows an electric circuit diagram of an inverting amplifier circuit formed on an LSI according to a conventional example, and its description will be given.

The inverting amplifier circuit shown in FIG. 7 is connected between an inverting amplifier 1 whose positive phase input terminal "+" is grounded, a negative phase input terminal "-" of the inverting amplifier 1 and a voltage supply terminal 2. Resistor R1, the output terminal of the inverting amplifier 1 and the negative phase input terminal "-"
And a resistor R2 connected between and.
The output terminal of the inverting amplifier 1 is connected to the voltage output terminal 3.

The back gate voltage (described later) of the resistors R1 and R2 is the power supply voltage VD of the inverting amplifier 1.
It is said to have the same voltage as. In this state, resistors R1 and R2
An arrow pointing upwards will be added above the symbol.

The structure of the resistors R1 and R2 on the LSI is as shown in the sectional view of FIG. 8, assuming that the resistors R1 and R2 are resistors by a normal diffusion process. In FIG. 8, reference numeral 5 is an N-channel substrate formed of an N-type semiconductor. Reference numeral 6 is a P-channel diffusion layer formed by diffusing a P-type semiconductor in the N-channel substrate 5. Reference numerals 7 and 8 are electrodes formed on the P-channel diffusion layer 6, and the voltages V1 and V2 at the electrodes 7 and 8 are the voltages across the resistor R1 or R2.

The back gate voltage described above is a voltage between the P-channel diffusion layer 6 and the N-channel substrate 5, and since the power supply voltage VD is applied to the N-channel substrate 5 in this example, the back gate voltage is the power supply voltage. It is VD.

The resistor R1 or R2 having such a structure is
It becomes a voltage-dependent type in which the resistance value changes as the voltages V1 and V2 at both ends increase and decrease. This is the voltage V across
When 1 and V2 increase, the reverse bias voltage at the junction (PN junction) between the P-channel diffusion layer 6 and the N-channel substrate 5 decreases, which narrows the width of the depletion layer 9 generated at the PN junction. The resistance value decreases and the voltage V across
This is because when 1 and V2 decrease, the reverse bias voltage at the PN junction increases, and the width of the depletion layer 9 widens, thereby increasing the resistance value.

As described above, when the substrate potential of the LSI, that is, the voltage of the N-channel substrate 5 is the power supply voltage VD, the resistance value of the voltage-dependent resistor R1 or R2 is R _V , R _V = R _HP − It is represented by α ₁ V1-β ₁ V2-γ ₁ V1V2.

However, R _HP is the original resistance value, α ₁ , β ₁ ,
γ ₁ is a coefficient of a voltage dependent portion determined by the semiconductor manufacturing process, α ₁ and β ₁ are first-order distortion coefficients, and γ ₁ is a second-order distortion coefficient.

Since it is difficult to obtain the coefficients of α ₁ , β ₁ and γ ₁ by calculation from the relationship with the process, they are obtained by combining the measured value and the formula. Usually α ₁ and β ₁
Has the same value, and γ ₁ is much smaller than α ₁ and β ₁ . Moreover, it is considered that the ratios of the coefficients α ₁ , β ₁ , and γ ₁ between the normal diffusion resistance and the resistance due to substrate separation are constant in the same process.

In the example of FIG. 7, the back gate voltage of each of the resistors R1 and R2 is the power supply voltage VD, but the back gate voltage may be the ground potential GND. In this case, the structure of the resistors R1 and R2 on the LSI is as shown in the sectional view of FIG. 9, assuming that the resistors R1 and R2 use a substrate separation process. In FIG. 9, reference numeral 11 is an N channel substrate formed of an N type semiconductor, and 12 is a P channel diffusion layer formed by diffusing a P type semiconductor into the N channel substrate 11. The N-channel substrate 11 and the P-channel diffusion layer 12 are resistors R1 or R
It is supposed to be used as 2.

Reference numerals 13 and 14 are P-channel substrates made of P-type semiconductor, and an N-channel substrate 11 which is a resistor is formed by using a substrate separation process that completely separates the LSI substrate.
It is completely separated from the LSI bases (N-channel bases) 15 and 16 by surrounding the periphery of. As a result, the N-channel substrate 11 and the P-channel diffusion layer 12 function as the resistor R1 or R2.

In the case of this configuration, the voltages V1 and V2 across the resistor R1 or R2 are such that the voltage V1 is the N-channel substrate 11
At a point where the electrode 17 formed on the P channel diffusion layer 12 and the electrode 17 formed on the P channel diffusion layer 12 are connected to each other.
Appears at the point where the electrode 19 formed on the N-channel substrate 11 and the electrode 20 formed on the P-channel diffusion layer 12 are connected.

The back gate voltage is a voltage between the N channel substrate 11 and the P channel substrates 13 and 14, and P
By grounding the channel substrates 13 and 14, the back gate voltage becomes the ground potential GND.

In such a structure, the voltage V
1 and V2 increase, grounded P channel substrate 1
The reverse bias voltage between the substrates 3, 14 and the N-channel substrate 11 increases, and the width of the depletion layers 21 and 22 formed at the junctions of the substrates 13, 14 and 11 increases, so that the resistance value increases.
When the voltages V1 and V2 at both ends are decreased, the reverse bias voltage at the junction is decreased, which results in depletion layers 21 and 22.
Since the width of is narrow, the resistance value decreases.

Thus, when the substrate potential of the LSI, that is, the voltage of the P-channel substrates 13 and 14 is the ground potential GND, and the resistance value of the voltage-dependent resistor R1 or R2 is R _g , R _g = R _SOI + α ₂ V1 + β ₂ V2 + γ ₂ V1V2 ...

However, R _SOI is the original resistance value, α ₂ ,
β ₂ and γ ₂ are coefficients of the voltage-dependent portion determined by the semiconductor manufacturing process, and are similar to α ₁ , β ₁ and γ ₁ used in the equation.

When the back gate voltage of the resistor by the diffusion process shown in FIG. 8 is set to the ground potential GND, the relationship between the N-type semiconductor and the P-type semiconductor is reversed, and the structure as shown in FIG. 9 is obtained. Good.

In FIG. 9, reference numeral 24 is a P channel substrate formed of a P type semiconductor, 25 is an N channel diffusion layer formed by diffusing an N type semiconductor into the P channel substrate 24, and 2
Electrodes 6 and 27 are formed on the N-channel diffusion layer 25. The voltages V1 and V2 at the electrodes 26 and 27 become the voltage across the resistor R1 or R2. The back gate voltage is ground potential GND by grounding the P-channel substrate 24.

In the resistor having such a configuration, the characteristic of the resistance value which changes in accordance with the increase and decrease of the voltages V1 and V2 across the resistor has the characteristic opposite to that of the resistor shown in FIG. That is,
The resistance value can be expressed by an equation.

Further, when the back gate voltage of the resistor in the substrate separation process shown in FIG. 9 is set to the power supply voltage VD, the relationship between the N-type semiconductor and the P-type semiconductor is reversed and the structure shown in FIG. Good.

In FIG. 11, reference numeral 28 is a P channel substrate formed of a P type semiconductor, and 29 is an N channel diffusion layer formed by diffusing an N type semiconductor into the P channel substrate 29. The P channel substrate 28 and the N channel diffusion layer 29 are adapted to be used as the resistor R1 or R2.

Reference numerals 30 and 31 denote N-channel substrates made of N-type semiconductor, which surround the P-channel substrate 28.
It is completely separated from the LSI substrates (P-channel substrate) 32 and 33. As a result, the P-channel substrate 28 and the N-channel diffusion layer 29 function as the resistor R1 or R2.

The voltages V1, V across the resistor R1 or R2
2 appears at the point where the voltage V1 connects the electrode 34 formed on the P-channel substrate 28 and the electrode 35 formed on the N-channel diffusion layer 29, and the voltage V2 is formed on the P-channel substrate 28. The formed electrode 36 and N channel diffusion layer 29
It appears at the point where the electrode 37 formed above is connected. Back gate voltage is based on N channel 3
By supplying the power supply voltage VD to 0 and 31, the power supply potential is obtained.

In the resistor having such a structure, the characteristic of the resistance value which changes in accordance with the increase and decrease of the voltages V1 and V2 across the resistor has the characteristic opposite to that of the resistor shown in FIG. That is,
The resistance value can be expressed by an equation.

[0027]

By the way, the normal LS
In I, since the base potential is either the potential of the power supply voltage VD or the ground potential GND, any one of the resistors having the structures of FIGS. When the inverting amplifier circuit as shown is configured, there is a problem that the output is distorted with respect to the input of the inverting amplifier 1 in the inverting amplifier circuit due to the influence of the resistance value that changes according to the voltage across the resistors R1 and R2. there were.

The present invention has been made in view of the above points, and provides an inverting amplifier circuit capable of substantially eliminating the output distortion of the inverting amplifier due to the influence of the changing resistance value of the voltage-dependent resistor. Is intended.

[0029]

FIG. 1 shows the principle of the present invention. The inverting amplifier circuit shown in FIG. 1 is configured by forming an inverting amplifier 1 and a voltage-dependent resistor on an LSI, and is characterized in that the back gate voltage is the power supply potential VD. The resistor R11 and the second resistor R12 whose back gate voltage is set to the ground potential GND are connected in series to either the positive phase input terminal “+” or the negative phase input terminal “−” of the inverting amplifier 1. The inverting amplifier 1 is connected as a reference resistor, and is connected in series with a third resistor R13 whose back gate voltage is a power supply potential and a fourth resistor R14 whose back gate voltage is a ground potential GND. A series-connected first and second resistor R11,
A feedback resistor is connected between the connection end of R12 and the output end of the inverting amplifier 1.

[0030]

According to the present invention described above, resistors (R11 and R12, or R13) whose resistance characteristics due to voltage dependence are opposite to each other are provided.
And R14) are connected in series to form a reference resistor and a feedback resistor of the inverting amplifier, the change amount of the resistance value due to the voltage dependence is canceled in the reference resistor and the feedback resistor. Therefore,
Since the resistance value changes due to the voltage dependence, the output distortion generated from the output terminal of the inverting amplifier is almost eliminated.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is an electric circuit diagram of an inverting amplifier circuit formed on an LSI according to an embodiment of the present invention. In the embodiment shown in this figure, the portions corresponding to the respective portions of the conventional example shown in FIG. 7 are denoted by the same reference numerals, and the description thereof will be omitted.

The inverting amplifier circuit of the embodiment shown in FIG. 2 is different from that shown in FIG. 7 in that a voltage supply terminal 2 and a resistor R1 are provided.
A resistor R3 whose back gate voltage is set to the ground potential GND, and a resistor R4 whose back gate voltage is set to the ground potential GND are connected between the resistors R1 and R2. There is something I did.

However, the back gate voltage is the ground potential G
The ND state is indicated by a downward arrow below the resistors R3 and R4. Thus resistor R3
3 shows an example of a structure on an LSI in which R1 and R1 or R4 and R2 are connected in series. Since the resistors R3 and R1 and the resistors R4 and R2 have the same series connection structure, the resistors shown in FIG. 3 are described as R3 and R1.

The resistors R3 and R1 shown in FIG. 3 are obtained by forming the resistor having the structure shown in FIG. 9 and the resistor having the structure shown in FIG. 8 on the same LSI. However, in FIG. 3, the portions corresponding to the respective portions of FIGS. 9 and 8 are denoted by the same reference numerals, and the description thereof will be omitted.

That is, the resistor R3 shown in FIG. 3 surrounds the N-channel substrate 11 on which the P-channel diffusion layer 12 serving as a resistor is formed, and is completely LSI substrates (N-channel substrate) 15 and 5. P-channel base 13, which is separated from
Since 14 is grounded, the back gate voltage is set to the ground potential GND. The back gate voltage of the resistor R1 is set to the power supply potential by applying the power supply voltage VD to the N channel substrate 5 on which the P channel diffusion layer 6 is formed.

In such a configuration, as described in the conventional example, in the resistor R3, the voltage V1 across the resistor R1,
When V2 increases, its resistance value increases and the voltage V
When 1 and V2 decrease, the resistance value decreases. Resistor R
In No. 1, the resistance value decreases as the voltages V2 and V3 at both ends increase, and the resistance value increases as the voltages V2 and V3 at both ends decrease.

That is, since the resistance characteristics of the resistors R3 and R1 due to the voltage dependence thereof are completely opposite, the change amounts of the resistance values depending on the voltage cancel each other out.
Therefore, when the inverting amplifier circuit is configured as shown in FIG. 2, the output is distorted with respect to the input of the inverting amplifier 1 due to the influence of the resistance value which changes according to the voltage across the resistor as in the conventional case. Can be almost eliminated. The effect is that the reference resistor R3 for the inverting amplifier 1
This is further improved by making R1 and the feedback resistors R4 and R2 similar to each other as shown in FIG.

In the above example, the resistor R shown in FIG.
3 was due to the substrate separation process shown in FIG. 9, and the resistor R1 was due to the diffusion process shown in FIG. However, the same effect can be obtained by using the diffusion process for the resistor R3 and the substrate separation process for the resistor R1.

FIG. 4 shows a configuration example in this case. That is, the resistor R3 shown in FIG. 4 has the structure shown in FIG. 10, and the resistor R1 has the structure shown in FIG. In FIG.
Portions corresponding to the respective portions in FIGS. 10 and 11 are designated by the same reference numerals.

Further, as shown in FIGS. 3 and 4, the resistor R3 formed by the diffusion process and the substrate separation process.
The reason for combining R1 and R1 is that they can be easily formed because the LSI substrate is either an N-channel substrate or a P-channel substrate. When the back gate voltages having different back gate voltages are combined in the same process, the channels of the substrate become different, which makes it difficult to manufacture.

Even if the series-connected resistor having the structure shown in FIG. 3 (or FIG. 4) is used only for the reference resistance portion as shown in FIG. 5, it is used for the feedback resistance portion as shown in FIG. Even if only it is used, the output distortion of the inverting amplifier 1 can be reduced as compared with the conventional case. Furthermore, FIG.
Even when the series configuration of FIGS. 5 and 6 is changed to the parallel configuration, the same effect can be obtained, though not to the same degree as the series configuration.

[0042]

As described above, according to the present invention,
The output distortion of the inverting amplifier due to the influence of the changing resistance value of the voltage-dependent resistor can be almost eliminated.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is an electric circuit diagram of an inverting amplifier circuit formed on an LSI according to an embodiment of the present invention.

FIG. 3 is a diagram showing a structure of a resistor on an LSI used in the inverting amplifier circuit shown in FIG.

4 is a diagram showing another structure of a resistor on an LSI used in the inverting amplifier circuit shown in FIG.

5 is an electric circuit diagram in the case where the resistor having the structure shown in FIG. 3 is used for the reference resistance portion of the inverting amplifier in the inverting amplifier circuit of the embodiment.

6 is an electric circuit diagram in the case where the resistor having the structure shown in FIG. 3 is used as a feedback resistor of the inverting amplifier in the inverting amplifier circuit of the embodiment.

FIG. 7 is an electric circuit diagram of an inverting amplifier circuit formed on an LSI according to a conventional example.

FIG. 8 is a diagram showing a structure of a resistor formed on an LSI by a normal diffusion process when a back gate voltage is a power supply potential.

FIG. 9 is a diagram showing a structure of a resistor formed on an LSI by a substrate separation process when a back gate voltage is a ground potential.

FIG. 10 is a diagram showing a structure of a resistor formed on an LSI by a normal diffusion process when the back gate voltage is ground potential.

FIG. 11 is a diagram showing a structure of a resistor formed on an LSI by a substrate separation process when a back gate voltage is a power supply potential.

[Explanation of symbols]

1 Inverting amplifier R11 First with back gate voltage set to power supply potential VD
Resistor R12 A second resistor whose back gate voltage is set to the ground potential GND R13 A third resistor whose back gate voltage is set to the power supply potential VD
Resistor R14 Fourth resistor whose back gate voltage is ground potential GND

Claims (5)

[Claims] 1. An inverting amplifier and a voltage-dependent resistor are L
In an inverting amplifier circuit formed on SI, a first resistor whose back gate voltage is a power supply potential and a second resistor whose back gate voltage is a ground potential are connected in series to each other, and A third resistor whose back gate voltage is the power supply potential and a fourth resistor whose back gate voltage is the ground potential are connected as a reference resistor to either the positive phase input terminal or the negative phase input terminal of the inverting amplifier. Connected in series as a feedback resistor between the connection end of the series-connected first and second resistors of the inverting amplifier and the output end of the inverting amplifier. An inverting amplifier circuit characterized by the above. 2. The inversion according to claim 1, wherein the first and second resistors are connected in parallel instead of being connected in series, and the third and fourth resistors are connected in parallel instead of being connected in series. Amplifier circuit. 3. A series connection arrangement of a resistor whose back gate voltage is a ground potential and a resistor whose back gate voltage is a power supply potential in the reference resistor,
2. The series connection arrangement of a resistor in which the back gate voltage of the feedback resistor is set to the ground potential and a resistor in which the back gate voltage is set to the power supply potential are similar to each other. Inversion amplifier circuit. 4. The reference resistor is configured by serially connecting a resistor whose back gate voltage is ground potential and a resistor whose back gate voltage is power supply potential,
2. The inverting amplifier circuit according to claim 1, wherein the feedback resistor is configured by using one of a resistor having a back gate voltage at a ground potential and a resistor having a back gate voltage at a power supply potential. . 5. The feedback resistor is configured by serially connecting a resistor having a back gate voltage at a ground potential and a resistor having a back gate voltage at a power supply potential, and the reference resistor is a back gate. The inverting amplifier circuit according to claim 1, wherein the inverting amplifier circuit is configured by using one of a resistor whose voltage is ground potential and a resistor whose back gate voltage is power supply potential.