Semiconductor integrated circuit

Abstract

To provide a resistance partial pressure circuit to which an influence of a voltage modulation is reduced.SOLUTION: A semiconductor integrated circuit 100 comprises a resistance partial pressure circuit 600. A first partial pressure resistance Rd1 is connected to between a first terminal P1 and a third terminal P3, and a second partial pressure resistance Rd2 is connected to between a second terminal P2 and a third terminal P3. A first bias resistance Rb1 and a second bias resistance Rb2 are serially connected to between the first terminal P1 and the second terminal P2. The first bias resistance Rb1 contains two first resistance elements r1 of which each resistance value is equal. In a well of the two first resistance elements r1 and a well of the first partial pressure resistance Rd1, a voltage Vb1 of a connection node of the two first resistance elements r1 is supplied. The second bias resistance Rb2 is also similar to the first bias resistance Rb1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to resistors formed in semiconductor integrated circuits. [Background technology]

[0002] Resistors are one of the important components of semiconductor integrated circuits. There are various types of resistors, such as polysilicon resistors, diffused resistors, and metal resistors, depending on the application.

[0003] The resistance value of resistors formed on semiconductor substrates changes slightly depending on the voltage applied to them. This is called voltage modulation. Voltage modulation is at most 0.1% or less when a large voltage exceeding 10V is applied, so it does not cause a problem in many applications. [overview]

[0004] However, in circuits that require high accuracy, even slight variations in resistance caused by voltage modulation can significantly deteriorate the circuit characteristics. When a resistor-based voltage divider circuit is formed, the voltage division ratio changes due to variations in resistance.

[0005] The present disclosure has been made in view of the above problems, and an exemplary purpose of an embodiment of the present disclosure is to provide a resistive voltage divider circuit that reduces the effects of voltage modulation. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a circuit diagram of a semiconductor integrated circuit including a resistive voltage divider circuit according to the embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a resistor. [Diagram 3] FIG. 3 is a cross-sectional view of a semiconductor integrated circuit including a resistor according to a comparative technique. [Figure 4] FIG. 4 is a diagram showing a simulation result of the resistance value of a resistor according to the embodiment and a resistor according to the comparative technique. [Diagram 5] FIG. 5 is a circuit diagram used in the simulation of FIG. [Figure 6] FIG. 6 is a cross-sectional view of a semiconductor integrated circuit including a resistor according to a modified example. [Figure 7] FIG. 7 is a circuit diagram of the amplifier circuit. [Figure 8] FIG. 8 is a circuit diagram of an amplifier circuit according to the embodiment. [Figure 9] FIG. 9 is a circuit diagram of an amplifier circuit according to a comparison technique. [Figure 10] FIG. 10 is a circuit diagram of a voltage monitoring circuit.

[0007] (Overview of the embodiment) A summary of some exemplary embodiments of the present disclosure will be described. This summary is intended to provide a simplified overview of some concepts of one or more embodiments for a basic understanding of the embodiments as a prelude to the detailed description that follows, and is not intended to limit the scope of the invention or disclosure. This summary is not intended to be an exhaustive overview of all possible embodiments, nor is it intended to identify key elements of all embodiments or to delineate the scope of some or all aspects. For convenience, the term "one embodiment" may be used to refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed in this specification.

[0008] A semiconductor integrated circuit according to one embodiment includes a resistive voltage divider circuit that generates a voltage obtained by dividing a voltage at a first terminal and a voltage at a second terminal at a third terminal. The resistive voltage divider circuit includes a first voltage divider resistor connected between the first terminal and the third terminal, a second voltage divider resistor connected between the second terminal and the third terminal, and a first bias resistor and a second bias resistor connected in series between the first terminal and the second terminal. The first bias resistor includes two first resistor elements having the same resistance value, and a voltage at a connection node between the two first resistor elements is supplied to a well of the two first resistor elements and a well of the first voltage divider resistor. The second bias resistor includes two second resistor elements having the same resistance value, and a voltage at a connection node between the two second resistor elements is supplied to a well of the two second resistor elements and a well of the second voltage divider resistor.

[0009] In this configuration, the first and second bias resistors function as a bias circuit that supplies a voltage to the well of the resistor. With this configuration, one resistor is divided into two resistor elements, and a voltage equivalent to the midpoint voltage is applied to the well of each resistor element, thereby reducing the effect of voltage modulation.

[0010] In one embodiment, at least one of the first voltage divider resistor and the second voltage divider resistor may be trimmable.

[0011] In one embodiment, the first voltage dividing resistor, the second voltage dividing resistor, the first bias resistor, and the second bias resistor may be polysilicon resistors.

[0012] In one embodiment, the first voltage dividing resistor, the second voltage dividing resistor, the first bias resistor, and the second bias resistor may be diffused resistors.

[0013] In one embodiment, the wells of the two first resistive elements may be independent and the wells of the two second resistive elements may be independent.

[0014] In one embodiment, the well of the two first resistive elements may be common, and the well of the two second resistive elements may be common.

[0015] In one embodiment, the semiconductor integrated circuit may further include an operational amplifier. The operational amplifier and the resistive voltage divider circuit may form a differential amplifier circuit.

[0016] In one embodiment, the semiconductor integrated circuit may further include a voltage comparator that compares the voltage of the third terminal with a threshold voltage. The voltage comparator and the resistive voltage divider circuit may form a voltage monitoring circuit.

[0017] (Embodiment) Hereinafter, preferred embodiments will be described with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be given the same reference numerals, and duplicated descriptions will be omitted as appropriate. In addition, the embodiments are illustrative and do not limit the disclosure and invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the disclosure and invention.

[0018] In this specification, "a state in which component A is connected to component B" includes a case in which component A and component B are directly physically connected to each other, and a case in which component A and component B are indirectly connected to each other via other components that do not substantially affect the electrical connection state between them or that do not impair the function or effect achieved by their combination.

[0019] Similarly, "a state in which component C is provided between components A and B" includes not only the case in which components A and C, or components B and C, are directly connected to each other, but also the case in which they are indirectly connected to each other via other components that do not substantially affect the electrical connection between them or that do not impair the functions or effects achieved by their combination.

[0020] 1 is a circuit diagram of a semiconductor integrated circuit 100 including a resistive voltage divider circuit 600 according to an embodiment. The resistive voltage divider circuit 600 has a first terminal P1, a second terminal P2, and a third terminal P3, divides a voltage V1 at the first terminal P1 and a voltage V2 at the second terminal P2, and generates a divided voltage V3 at the third terminal P3.

[0021] The resistive voltage dividing circuit 600 includes a first voltage dividing resistor Rd1, a second voltage dividing resistor Rd2, a first bias resistor Rb1, and a second bias resistor Rb2.

[0022] The first voltage dividing resistor Rd1 is connected between the first terminal P1 and the third terminal P3, and the second voltage dividing resistor Rd2 is connected between the second terminal P2 and the third terminal P3. In other words, the first voltage dividing resistor Rd1 and the second voltage dividing resistor Rd2 are connected in series between the first terminal P1 and the second terminal P2, and the connection node of the first voltage dividing resistor Rd1 and the second voltage dividing resistor Rd2 is the third terminal P3.

[0023] The voltage V3 at the third terminal P3 is expressed by the formula (1). V3=(V1×Rd2+V2×Rd1) / (Rd1+Rd2) …(1)

[0024] The first bias resistor Rb1 and the second bias resistor Rb2 constitute a bias circuit 610. The first bias resistor Rb1 and the second bias resistor Rb2 are connected in series between the first terminal P1 and the second terminal P2, and connected in parallel to the first voltage dividing resistor Rd1 and the second voltage dividing resistor Rd2. The ratio of the first bias resistor Rb1 to the second bias resistor Rb2 is equal to the ratio of the first voltage dividing resistor Rd1 to the second voltage dividing resistor Rd2. Rb1:Rb2=Rd1:Rd2 …(2)

[0025] The first bias resistor Rb1 includes two first resistor elements (also called sub resistors) r1 that have the same resistance value and are connected in series. The second bias resistor Rb2 includes two second resistor elements r2 that have the same resistance value and are connected in series.

[0026] In Fig. 1, the rectangle surrounding each resistor (resistance element) represents a well. In this embodiment, the two resistance elements r1 of the first bias resistor Rb1 are formed in a common well. Similarly, the two resistance elements r2 of the second bias resistor Rb2 are formed in a common well.

[0027] The wells of the two first resistor elements r1 and the first voltage dividing resistor Rd1 are supplied with a voltage (called a first bias voltage) Vb1 at the connection node of the two first resistor elements r1. The wells of the two second resistor elements r2 and the second voltage dividing resistor Rd2 are supplied with a voltage (called a second bias voltage) Vb2 at the connection node of the two second resistor elements r2.

[0028] The first voltage dividing resistor Rd1, the second voltage dividing resistor Rd2, the first bias resistor Rb1, and the second bias resistor Rb2 are polysilicon resistors or diffused resistors.

[0029] The above is the configuration of the resistive voltage divider circuit 600. Next, the configurations of the first bias resistor Rb1 and the second bias resistor Rb2 will be described.

[0030] 2 is a cross-sectional view of a resistor 200. The resistor 200 is the first bias resistor Rb1 or the second bias resistor Rb2 of FIG 1. The resistor 200 is formed on the semiconductor substrate 110. The resistor 200 has a first end 202 and a second end 204.

[0031] A well 112 is formed in a semiconductor substrate 110. A resistor 200 is formed on the well 112. The resistor 200 is formed by dividing it into resistive elements 210 and 212 that are connected in series between a first end 202 and a second end 204. When the design value of the resistance value of the resistor 200 is r, the resistive elements 210 and 212 are designed to have the same resistance value of r / 2. The resistive elements 210 and 212 are polysilicon resistors or diffused resistors.

[0032] A voltage Vb1 corresponding to a midpoint voltage between the voltage at the first end 202 and the voltage at the second end 204 is applied to the well 112. Specifically, the well 112 is connected to a connection node 206 between the resistance elements 210 and 212.

[0033] The above is the configuration of the resistor 200. The advantages of the resistor 200 become clear when compared with a comparative technique. Therefore, the comparative technique will be described first.

[0034] 3 is a cross-sectional view of a semiconductor integrated circuit 100R including a resistor 200R according to a comparative technique. The resistor 200R includes a single resistive element 214 having a resistance value r formed on a well 112. The well 112 is connected to one of a first end 202 and a second end 204 (here, the second end 204). The above is the configuration of the resistor 200R.

[0035] FIG. 4 is a diagram showing a simulation result of the resistance value of the resistor 200 according to the embodiment and the resistor 200R according to the comparative technology. FIG. 5 is a circuit diagram used in the simulation of FIG. 4. The design values ​​of the resistors 200 and 200R are 1 kΩ. In the circuit (i), the second terminal 204 of the resistor 200 is grounded, and the first terminal 202 is connected to the variable voltage source 900. In the circuit (ii), the second terminal 204 of the resistor 200R is grounded, and the first terminal 202 is connected to the variable voltage source 900. In the circuit (iii), the first terminal 202 of the resistor 200R is grounded, and the second terminal 204 is connected to the variable voltage source 900. The voltage V of the variable voltage source 900 is DD The voltage is swept from 0 to 10 V, the current flowing through the resistor is measured, and the resistance value is calculated from the voltage and current.

[0036] As shown in FIG. 4, in the circuits (ii) and (iii) using the resistor 200R according to the comparative technology, the resistance value r is DD In contrast, in the circuit (i) using the resistor 200 according to the embodiment, the resistance value r changes according to the power supply voltage V DD It is clear that the effect of voltage modulation is suppressed.

[0037] Return to FIG. 1. In the resistive voltage divider circuit 600 of FIG. 1, the first bias resistor Rb1 and the second bias resistor Rb2 of the bias circuit 610 have the configuration of the resistor 200 of FIG. 2, so that the effect of voltage modulation is suppressed, and therefore the resistance values ​​of the first bias resistor Rb1 and the second bias resistor Rb2 are stable. And, since the first bias voltage Vb1 generated in the first bias resistor Rb1 is supplied to the well of the first voltage divider resistor Rd1, the effect of voltage modulation is also suppressed in the first voltage divider resistor Rd1, and the resistance value is stable. And, since the second bias voltage Vb2 generated in the second bias resistor Rb2 is supplied to the well of the second voltage divider resistor Rd2, the effect of voltage modulation is also suppressed in the second voltage divider resistor Rd2, and the resistance value is stable.

[0038] As a result, the resistive voltage divider circuit 600 of FIG. 1 can suppress fluctuations in the voltage division ratio determined by the two resistance values ​​Rd1 and Rd2.

[0039] 6 is a cross-sectional view of a semiconductor integrated circuit 100a including a resistor 200a according to a modified example. In this modified example, two resistive elements 210 and 212 are formed separately in independent wells 112_1 and 112_2. The wells 112_1 and 112_2 are connected to a connection node 206 between the first resistive element r1 and the second resistive element r2. This configuration can also suppress the effect of resistance modulation, as in the resistor 200 of FIG. 2. However, in this modified example, since the wells 112_1 and 112_2 are independent, the circuit area is larger than that of the resistor 200 of FIG. 2.

[0040] Next, applications of the resistive voltage divider circuit 600 will be described. The resistive voltage divider circuit 600 can be suitably used in circuits that require high accuracy on the order of 0.1%. For example, a suitable application of the resistive voltage divider circuit 600 is an amplifier circuit that is a combination of an operational amplifier and resistors.

[0041] 7 is a circuit diagram of the amplifier circuit 400. The amplifier circuit 400 is a subtraction amplifier including an operational amplifier 402 and resistors R11 to R14. R11=R13 and R12=R14 are established, and the gain of the amplifier circuit 400 is g=R13 / R11.

[0042] The pair of resistors R11 and R12 and the pair of resistors R13 and R14 form a resistive voltage divider circuit. Therefore, the configuration of the resistive voltage divider circuit 600 described above can be applied.

[0043] Fig. 8 is a circuit diagram of an amplifier circuit 400A according to an embodiment. In the amplifier circuit 400A of Fig. 8, a pair of resistors R11 and R12 constitutes a resistive voltage dividing circuit 600_1, and similarly, a pair of resistors R13 and R14 constitutes a resistive voltage dividing circuit 600_2. Each of the resistive voltage dividing circuits 600_1 and 600_2 has the configuration of the resistive voltage dividing circuit 600 of Fig. 1. Bias resistors corresponding to the resistors R11 to R14, respectively, are shown as R11b to R14b.

[0044] The advantages of the amplifier circuit 400A of FIG. 8 become clear when compared with the comparative art.

[0045] 9 is a circuit diagram of an amplifier circuit 400B according to a comparative technique. In the comparative technique, resistors R11 to R14 have the same configuration as the first bias resistor Rb1 and the second bias resistor Rb2 in FIG.

[0046] Even with the configuration of FIG. 9, the resistance value of each of the resistors R11 to R14 is stable because it is not easily affected by voltage modulation. Here, the operational amplifier 402 generally has an offset, and in order to remove the effect of this offset, one or more of the resistors R11 to R14 may be configured to be trimmable, that is, to be finely adjustable in resistance value. In the example of FIG. 9, it is assumed that the resistance value of the resistor R14 is trimmable. The configuration of the trimmable resistor is not particularly limited, but for example, the resistor R14 is configured as a series connection circuit R14_2 of multiple adjustment resistors in addition to a reference resistor R14_1. A switch is connected in parallel to each of the multiple adjustment resistors, and each switch can be controlled to be on or off. The area of ​​the resistor R14 configured to be trimmable is larger than the area of ​​the resistor R12 that has the same resistance value but is not trimmable.

[0047] The present inventors have studied the configuration of Fig. 9 and recognized the following problem. A PN junction exists between the well of the resistor and the semiconductor substrate. Since this PN junction is in a reverse bias state, a leakage current substantially flows through the PN junction from the well to the substrate. In other words, leakage currents I1 to I4 flow through resistors R11, R12, R13, and R14. In Fig. 9, the leakage currents I1 to I4 are indicated by current source symbols.

[0048] When I1=I3 and I2=I4 are satisfied, the leakage current does not affect the offset voltage. However, although the design values ​​of resistors R12 and R14 are equal, resistor R14 is configured to be trimmable, so the well area of ​​resistor R14 is larger than the well area of ​​resistor R12. As a result, the leakage current I4 of resistor R14 is larger than the leakage current I2 of resistor R12. This imbalance between the leakage currents I2 and I4 causes the offset voltage of amplifier circuit 400B.

[0049] Returning to FIG. 8, in FIG. 8, leakage currents I1 to I4 flow in the bias circuit 610 of each of the resistive voltage divider circuits 600_1 and 600_2. The resistor R14 is configured to be trimmable, but the bias resistor R14b of the bias circuit 610 does not need to be trimmed. Therefore, the well areas of the bias resistor R14b corresponding to the resistor R14 and the bias resistor R12b corresponding to the resistor R12 can be made equal, and I2≈I4 can be satisfied. This makes it possible to reduce the change in offset voltage caused by the trimmable resistor R14.

[0050] The amplifier circuit is not limited to a subtracting amplifier, but may be a non-inverting amplifier or an inverting amplifier.

[0051] Another example of an application of the resistive voltage divider circuit 600 is a voltage monitoring circuit.

[0052] 10 is a circuit diagram of a voltage monitoring circuit 700. The voltage monitoring circuit 700 includes a resistive voltage divider circuit 600 and a voltage comparator 702. The resistive voltage divider circuit 600 detects an input voltage V IN The voltage comparator 702 divides the divided voltage V IN ' is the threshold voltage V TH According to this configuration, the voltage division ratio of the resistive voltage divider circuit 600 is not easily affected by voltage modulation, so that accurate voltage comparison is possible.

[0053] (Additional Note) One aspect of the technology disclosed in this specification can be understood as follows.

[0054] (Item 1) A resistor voltage divider circuit is provided which divides the voltage of the first terminal and the voltage of the second terminal and generates the divided voltage at the third terminal. The resistor voltage divider circuit includes: a first voltage dividing resistor connected between the first terminal and the third terminal; a second voltage dividing resistor connected between the second terminal and the third terminal; a first bias resistor and a second bias resistor connected in series between the first terminal and the second terminal; Equipped with the first bias resistor includes two first resistor elements having the same resistance value, and a voltage of a connection node between the two first resistor elements is supplied to a well of the two first resistor elements and a well of the first voltage dividing resistor; A semiconductor integrated circuit, wherein the second bias resistor includes two second resistance elements having the same resistance value, and a voltage of a connection node of the two second resistance elements is supplied to a well of the two second resistance elements and a well of the second voltage dividing resistor.

[0055] (Item 2) 2. The semiconductor integrated circuit according to item 1, wherein at least one of the first voltage dividing resistor and the second voltage dividing resistor is trimmable.

[0056] (Item 3) 3. The semiconductor integrated circuit according to item 1 or 2, wherein the first voltage dividing resistor, the second voltage dividing resistor, the first bias resistor, and the second bias resistor are polysilicon resistors.

[0057] (Item 4) 3. The semiconductor integrated circuit according to item 1 or 2, wherein the first voltage dividing resistor, the second voltage dividing resistor, the first bias resistor, and the second bias resistor are diffused resistors.

[0058] (Item 5) the wells of the two first resistor elements are independent; 5. The semiconductor integrated circuit according to any one of items 1 to 4, wherein the wells of the two second resistance elements are independent.

[0059] (Item 6) the well of the two first resistor elements is common; 5. The semiconductor integrated circuit of any one of items 1 to 4, wherein the well of the two second resistor elements is common.

[0060] (Item 7) It also has an operational amplifier. 7. The semiconductor integrated circuit according to any one of items 1 to 6, wherein the operational amplifier and the resistive voltage divider circuit constitute a differential amplifier circuit.

[0061] (Item 8) a voltage comparator for comparing the voltage at the third terminal with a threshold voltage; 7. The semiconductor integrated circuit according to any one of items 1 to 6, wherein the voltage comparator and the resistive voltage divider circuit constitute a voltage monitoring circuit. [Explanation of symbols]

[0062] 100 Semiconductor integrated circuit 110 Semiconductor substrate 112 well 200 Resistance 202 1st end 204 2nd end r1 First resistance element r2 2nd resistance element 400 Amplification circuit 402 Operational Amplifier 600 Resistor divider circuit P1 1st terminal P2 2nd terminal P3 3rd terminal Rd1 1st voltage divider resistor Rd2 Second voltage divider resistor 610 Bias Circuit Rb1 First bias resistor r1 First resistance element Rb2 Second bias resistor r2 2nd resistance element

Claims

1. a resistor voltage divider circuit that generates a voltage obtained by dividing a voltage at a first terminal and a voltage at a second terminal at a third terminal; The resistor voltage divider circuit includes: a first voltage dividing resistor connected between the first terminal and the third terminal; a second voltage dividing resistor connected between the second terminal and the third terminal; a first bias resistor and a second bias resistor connected in series between the first terminal and the second terminal; Equipped with the first bias resistor includes two first resistor elements having the same resistance value, and a voltage of a connection node of the two first resistor elements is supplied to a well of the two first resistor elements and a well of the first voltage dividing resistor; A semiconductor integrated circuit, wherein the second bias resistor includes two second resistance elements having the same resistance value, and a voltage of a connection node of the two second resistance elements is supplied to a well of the two second resistance elements and a well of the second voltage dividing resistor.

2. 2. The semiconductor integrated circuit according to claim 1, wherein at least one of said first voltage dividing resistor and said second voltage dividing resistor is trimmable.

3. 3. The semiconductor integrated circuit according to claim 1, wherein the first voltage dividing resistor, the second voltage dividing resistor, the first bias resistor, and the second bias resistor are polysilicon resistors.

4. 3. The semiconductor integrated circuit according to claim 1, wherein the first voltage dividing resistor, the second voltage dividing resistor, the first bias resistor, and the second bias resistor are diffused resistors.

5. the wells of the two first resistor elements are independent; 3. The semiconductor integrated circuit according to claim 1, wherein the wells of the two second resistance elements are independent of each other.

6. the well of the two first resistor elements is common; 3. The semiconductor integrated circuit according to claim 1, wherein the two second resistor elements share a common well.

7. Further equipped with op amps, 3. The semiconductor integrated circuit according to claim 1, wherein said operational amplifier and said resistive voltage divider circuit constitute a differential amplifier circuit.

8. a voltage comparator for comparing the voltage at the third terminal with a threshold voltage; 3. The semiconductor integrated circuit according to claim 1, wherein said voltage comparator and said resistive voltage divider circuit constitute a voltage monitoring circuit.

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