Resistance circuit and current detection circuit having the same

Abstract

Provided are a resistance circuit and a current detection circuit having the same, which have small temperature dependence, can adjust a resistance value in a wide range from a high resistance value to a low resistance value, and have a small area. A resistance circuit connected between a first terminal and a second terminal and having a variable resistance value, the resistance circuit having a reference resistance, a series variable resistance group, and a parallel variable resistance group, the series variable resistance group having N parallel variable resistance units (RP(1) to (N)) connected in series with each other, the N parallel variable resistance units each having a resistance and a trimming element connected in parallel with the resistance, the parallel variable resistance group having M series variable resistance units (RS(1) to (M)) connected in parallel with each other, the M series variable resistance units each having a resistance and a trimming element connected in series with the resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to a resistance circuit and a current detection circuit having the same. BACKGROUND

[0002] As for a resistance circuit of a semiconductor integrated circuit, there is a technique in which an insulating layer is provided on a silicon substrate, and a polysilicon layer formed on the insulating layer is used as a resistance element. It is known that the temperature dependence of the resistance value of the polysilicon used as the resistance element varies depending on the dose at which impurities are ion implanted into the polysilicon (for example, refer to Patent Literature 1).

[0003] Therefore, in order to obtain a resistance element of polysilicon having small temperature dependence, it is necessary to control the dose implanted into the polysilicon layer within a fixed range. On the other hand, the sheet resistance value (resistance value per unit area) of the polysilicon depends on the dose. Therefore, the sheet resistance value of the polysilicon resistance having small temperature dependence converges to a fixed range.

[0004] Further, in a case where a constant voltage output circuit is formed by a semiconductor integrated circuit, for example, the resistance value of the resistance circuit is changed by trimming using a trimming element, and the division ratio of a voltage dividing circuit is set to a desired value.

[0005] Specifically, in a case where the resistance value of a unit resistance is set to 1R, for example, resistances of 1 / 16R, 1 / 8R, 1 / 4R, 1 / 2R, and 1R are connected in series, and fuses are provided in parallel with each of the resistances, respectively. The fuses are arbitrarily cut in a trimming process at the time of manufacturing, and thereby the resultant resistance of the entire resistance circuit is set to a desired resistance value. The resistance value of each of the resistances connected in parallel with the fuses is set to 2n (n is a consecutive integer) times the unit resistance, and thereby a resistance circuit having a desired resistance value in a range of substantially continuous resistance values can be obtained.

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2020-21909

[0007] In a case where a current detection circuit is implemented by a semiconductor integrated circuit, as a method of mainly detecting a current in a range of several mA (Milliampere) to several 100 mA, current sensing is performed by measuring a voltage generated by a current flowing through a resistance circuit for current detection. In such a resistance circuit for current detection, in addition to small temperature dependence of the resistance value, it is required that the resistance circuit be able to adjust the resistance value with high precision in a large range from a high resistance value to a low resistance value according to a current value to be detected.

[0008] However, in the case of the existing resistance circuit in which the resistance value is variable, in order to adjust the resistance value with high precision, it is necessary to reduce the minimum resistance value of the resistance connected in parallel with the fuse. As described above, the resistance value of the thin layer in the case of small temperature dependence of the resistance element formed of polysilicon is fixed, and thus it is not possible to arbitrarily reduce the resistance value of the unit resistance.

[0009] As a technique for further reducing the minimum resistance value of the resistance circuit, there are, for example, a technique of increasing the number of resistances connected in parallel, and a technique of shortening the length L of the unit resistance and enlarging the width W of the unit resistance.

[0010] However, in the case of applying the technique of increasing the number of resistances connected in parallel, in order to realize a resistance value of n that is smaller than the resistance value 1R of the unit resistance, i.e., a smaller resistance value of 1 / 32R, 1 / 64R, 1 / 128R, it is necessary to connect 32, 64, 128 resistance elements in parallel, respectively. In the structure in which such resistance elements are connected in parallel, since a very large number of resistance elements are included, the circuit area becomes large, and this in turn leads to an increase in the cost of the semiconductor chip.

[0011] Further, in the case of reducing the resistance value of the unit resistance by adopting the technique of shortening the length L of the unit resistance and enlarging the width W of the unit resistance, the number of series resistances for adjusting the resistance value of the entire resistance circuit to a higher resistance value increases. In this case, since the circuit area becomes large, this also leads to an increase in the cost of the semiconductor chip. SUMMARY

[0012] The present application has been made in view of the above problems, and it is an object to provide a resistance circuit having small temperature dependence, and capable of adjusting the resistance value substantially continuously in a large range from a high resistance value to a low resistance value, and having a small circuit area, and a current detection circuit having the resistance circuit.

[0013] The resistance circuit of the embodiment of the present application is a resistance circuit connected between a first terminal and a second terminal and having a variable resistance value, characterized by comprising: a reference resistance; a series variable resistance group connected in series with the reference resistance; and a parallel variable resistance group connected in parallel with the reference resistance, the series variable resistance group having N parallel variable resistance units connected in series with each other, an Nth parallel variable resistance unit having an Nth resistance and an Nth trimming element connected in parallel with the Nth resistance, the parallel variable resistance group having M series variable resistance units connected in parallel with each other, an Mth series variable resistance unit having an Mth resistance and an Mth trimming element connected in series with the Mth resistance, the M and the N each being an integer of 1 or more.

[0014] According to the present application, a resistance circuit having a small temperature dependence, capable of adjusting a resistance value substantially continuously in a wide range from a high resistance value to a low resistance value, and a small area, and a current detection circuit having the resistance circuit can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 FIG. 1 is a circuit diagram showing a general structure of a resistance circuit according to the present application (parallel variable resistance units: N, series variable resistance units: M).

[0016] Figure 2 FIG. 2 is a circuit diagram showing a structure example of a parallel variable resistance unit in the resistance circuit according to the present embodiment.

[0017] Figure 3 FIG. 3 is a circuit diagram showing a structure example of a series variable resistance unit in the resistance circuit according to the present embodiment.

[0018] Figure 4 FIG. 4 is a circuit diagram showing a specific structure example of the resistance circuit according to the present embodiment (parallel variable resistance units: 5, series variable resistance units: 5).

[0019] Figure 5 FIG. 5 is a circuit diagram showing a specific structure example of a series variable resistance group (in the case where the parallel variable resistance units are 5 (N = 5)).

[0020] Figure 6 FIG. 6 is a circuit diagram showing a specific structure example of a parallel variable resistance group (in the case where the series variable resistance units are 5 (M = 5)).

[0021] Figure 7 FIG. 7 is a table showing the number of resistors in the specific structure example of the resistance circuit according to the present embodiment (parallel variable resistance units: 5, series variable resistance units: 5).

[0022] Figure 8 FIG. 8 is a table showing the number of resistors in the resistance circuit according to the comparative example.

[0023] Figure 9 FIG. 9 is a circuit diagram showing a structure example of a current detection circuit having the resistance circuit according to the present embodiment.

[0024] REFERENCE NUMERALS

[0025] 1: first terminal; 2: second terminal; 10: series variable resistance group; 20: parallel variable resistance group; R0: reference resistance; RP(N): (Nth) parallel variable resistance unit; RS(M): (Mth) series variable resistance unit; R1[N], R2[M]: resistance; T1[N], T2[M]: trimming element; 100, 100a: resistance circuit; 200: current detection circuit; 111: output transistor; 5: sensing output terminal (output terminal). DETAILED DESCRIPTION

[0026] Hereinafter, a resistance circuit of an embodiment of the present application and a current detection circuit having the resistance circuit will be described with reference to the drawings.

[0027] Figure 1 is a circuit diagram showing a generalized structure of the resistance circuit 100 as an example of the resistance circuit of the present embodiment (N parallel variable resistance units and M series variable resistance units, N and M each being an integer of 1 or more).

[0028] The resistance circuit 100 has a first terminal 1, a second terminal 2, a reference resistance R0, a series variable resistance group 10 connected in series with the reference resistance R0, and a parallel variable resistance group 20 connected in parallel with the reference resistance R0.

[0029] The reference resistance R0 has a resistance element including a polysilicon layer of a length L and a width W with a first end R0a and a second end R0b as both ends. The resistance element of the reference resistance R0 is composed of a single resistance element or a plurality of resistance elements connected in series or in parallel.

[0030] Here, a resistance element formed of the same polysilicon layer as the reference resistance R0 and having the same length and width as the reference resistance R0, i.e., the length L and the width W, is referred to as a "unit resistance". Also, regarding the polysilicon layer, the dose of ion implantation at the time of manufacture is adjusted so that the ideal temperature dependence is zero.

[0031] The series variable resistance group 10 has a first end 10a connected to the first terminal 1, N parallel variable resistance units RP(1) to RP(N), and a second end 10b connected to the first end R0a of the reference resistance R0.

[0032] The N parallel variable resistance units RP(1) to RP(N) have the parallel variable resistance unit RP(1), the parallel variable resistance unit RP(2),..., the parallel variable resistance unit RP(N-1), and the parallel variable resistance unit RP(N) connected in series in this order from the first end 10a toward the second end 10b.

[0033] The parallel variable resistance group 20 has a first end 20a connected to the first end R0a of the reference resistance R0, M series variable resistance units RS(1) to RS(M), and a second end 20b connected to the second end R0b of the reference resistance R0.

[0034] The M series variable resistance units RS(1) to RS(M) are connected in parallel between the first end 20a and the second end 20b with the series variable resistance unit RS(1), the series variable resistance unit RS(2),..., (omitted),..., the series variable resistance unit RS(M-1), and the series variable resistance unit RS(M). Further, the first end 20a and the second end 20b are connected to the first end R0a and the second end R0b, respectively, and thus each of the series variable resistance units RS(1) to RS(M) is also connected in parallel to the reference resistance R0.

[0035] The resistance value of the resistance circuit 100 as a whole between the first terminal 1 and the second terminal 2 is determined in accordance with a resultant resistance composed of the reference resistance R0, the series variable resistance group 10, and the parallel variable resistance group 20. As will be described later, each of the parallel variable resistance units RP(1) to RP(N) and the series variable resistance units RS(1) to RS(M) has a trimming element. Each of the parallel variable resistance units RP(1) to RP(N) and the series variable resistance units RS(1) to RS(M) is configured to be able to adjust the resistance value in accordance with whether the trimming element is in a connected state or in a non-connected state.

[0036] Figure 2 is a circuit diagram showing a configuration example of the Nth parallel variable resistance unit RP(N) among the parallel variable resistance units RP(1) to RP(N).

[0037] Each of the N parallel variable resistance units RP has a resistance R1 and a trimming element T1[N] connected in parallel to the resistance R1. That is, the Xth parallel variable resistance unit RP(X) has a resistance R1[X] as a resistance and a trimming element T1[X] as a trimming element connected in parallel to the resistance R1[X], respectively. Here, X is an integer satisfying 1 ≤ X ≤ N. The Nth parallel variable resistance unit RP(N) has a resistance R1[N] as an Nth resistance and a trimming element T1[N] as an Nth trimming element connected in parallel to the resistance R1[N].

[0038] One terminal of the parallel variable resistance unit RP(N) is connected to the first terminal of the trimming element T1[N] and the first terminal of the resistor R1[N]. The other terminal of the parallel variable resistance unit RP(N) is connected to the second terminal of the trimming element T1[N] and the second terminal of the resistor R1[N]. That is, the parallel variable resistance unit RP(X) includes a first terminal connected to the first terminal of the trimming element T1[X] and the first terminal of the resistor R1[X], and a second terminal connected to the second terminal of the trimming element T1[X] and the second terminal of the resistor R1[X].

[0039] Here, the resistor R1[X] is composed of one unit resistor or a plurality of unit resistors connected in series or in parallel. The trimming element T1[X] is an element capable of switching from a connected state to a non-connected state, and is, for example, a fuse. The fuse is in the connected state in an initial state before the trimming process. In addition, the resistance value of the fuse is sufficiently smaller than the resistance value of the resistor R1[X]. Therefore, the combined resistance of the fuse in the connected state and the resistor R1[X] is approximately the same as the resistance value of the fuse.

[0040] In the trimming process, when the trimming element T1[X] is in the non-connected state, that is, the fuse is cut, the fuse becomes a resistance value much higher than the resistance value of the resistor R1[X]. Therefore, the combined resistance of the fuse in the non-connected state and the resistor R1[X] is approximately the same as the resistance value of the resistor R1[X]. In this way, the resistance value of the parallel variable resistance unit RP(X) is changed depending on the presence or absence of processing (cutting) of the fuse, that is, the connected state and the non-connected state of the trimming element T1[X].

[0041] Figure 3 is a circuit diagram showing a structure example of the Mth series variable resistance unit RS(M) among the series variable resistance units RS(1) to RS(M).

[0042] The M series variable resistance units RS each have a resistor R2 and a trimming element T2 connected in series with the resistor R2. That is, the Xth series variable resistance unit RS(X) has a resistor R2[X] as a resistor and a trimming element T2[X] as a trimming element connected in series with the resistor R2[X]. Here, X is an integer satisfying 1 ≤ X ≤ M. The Mth series variable resistance unit RS(M) has a resistor R2[M] as an Mth resistor and a trimming element T2[M] as an Mth trimming element connected in series with the resistor R2[M].

[0043] One terminal of the series variable resistance unit RS(M) is connected to the first terminal of the trimming element T2[M]. The second terminal of the trimming element T2[M] is connected to the first terminal of the resistance R2[M]. The second terminal of the resistance R2[M] is connected to the other terminal of the series variable resistance unit RS(M). That is, the series variable resistance unit RS(X) includes the first terminal connected to the first terminal of the trimming element T2[X], and the second terminal connected to the second terminal of the resistance R2[M].

[0044] Here, the resistance R2[X] is composed of one unit resistance, or a plurality of unit resistances connected in series or in parallel. The trimming element T2[X] is an element capable of switching from the connected state to the non-connected state, and is, for example, a fuse. The resistance value of the fuse is sufficiently smaller than the resistance value of the resistance R2[X]. Therefore, the combined resistance of the fuse as the trimming element T2[X] and the resistance R2[X] is approximately the same as the resistance value of the resistance R2[X].

[0045] In the trimming process, when the trimming element T2[X] is in the non-connected state, that is, the fuse is cut, the fuse becomes a resistance value much higher than that of the resistance R2[X]. Therefore, the combined resistance of the fuse in the non-connected state and the resistance R2[X] is a resistance value much higher than that of the resistance R2[X]. In this way, the resistance value of the series variable resistance unit RS(X) is changed depending on the presence or absence of the processing (cutting) of the fuse, that is, the connected state and the non-connected state of the trimming element T2[X].

[0046] The resistance circuit 100 is preferably configured to be able to adjust the resistance value with high precision in the entire range of a large range from a high resistance value to a low resistance value. If considering enabling adjustment of the resistance value with high precision in the entire range of a large range from a high resistance value to a low resistance value, the resistance circuit 100 is preferably configured to satisfy the following equation (1). In the following equation (1), R0 is the resistance value of the reference resistance R0, R para is the combined resistance value of the reference resistance R0 and the parallel variable resistance group 20 before trimming, R 1min is the resistance value R 11 of the resistance R1[N], R 1N is the smallest resistance value among the resistance values R 2max of the resistances R2[1] to R2[M], and R 21 is the largest resistance value among the resistance values R 2M of the resistances R2[1] to R2[M].

[0047] [Mathematical Expression 1]

[0048] 2R0-(R0 -1 +R 2max -1 ) -1 -R para -R1min > 0... (1)

[0049] According to the resistance circuit 100 in accordance with the above-described equation (1), the adjustment accuracy does not deteriorate in a region of resistance values that can be obtained after a certain trimming is performed. That is, the resistance value can be adjusted with high accuracy substantially continuously over a wide range.

[0050] Further, from the viewpoint of suppressing an increase in the area of the resistance circuit 100, it is effective to reduce the overlap of the adjustment ranges of the resistance values based on the series variable resistance group 10 and the parallel variable resistance group 20. If the circuit area of the resistance circuit 100 is considered to be suppressed within an appropriate range, the resistance circuit 100 is preferably configured to satisfy the following equation (2). In addition, R0, R para and R 1min are the same as the above-described equation (1).

[0051] [Mathematical expression 2]

[0052]

[0053] According to the resistance circuit 100 in accordance with the above-described equation (2), the overlap of the adjustment ranges of the resistance values based on the series variable resistance group 10 and the parallel variable resistance group 20 can be reduced, and further, an increase in the circuit area can be suppressed.

[0054] If the resistance circuit 100 is configured in such a manner that the above-described equation (1) and the above-described equation (2) are both satisfied, it is more preferable than the resistance circuit 100 configured to satisfy only the above-described equation (1) or only the above-described equation (2). The resistance circuit 100 that satisfies both the above-described equation (1) and the above-described equation (2) can adjust the resistance value with high accuracy over the entire range from a high resistance value to a low resistance value, and further, an increase in the circuit area can be suppressed.

[0055] The adjustment range of the resistance value of the resistance circuit 100 is the range in which all of the trimming elements T1 [1] to T1 [N] and the trimming elements T2 [1] to T2 [M] are from the connected state to the state in which all of them are non-connected (cut off). In a case where the smallest resistance value that can be adjusted is set to R 100min , the largest resistance value is set to R 100max , and the resistance values of the fuses are ignored, R 100min and R 100max are the following equation (3) and the following equation (4), respectively. Here, X is an integer that satisfies 1 ≤ X ≤ N.

[0056] [Mathematical expression 3]

[0057] R 100min = R para ... (3)

[0058]

[0059] The resistance circuit 100 can adjust its resistance value in the range of R 100min to R 100max . The adjustable range of the resistance value of the resistance circuit 100 can be easily changed by changing the design value of N representing the number of parallel variable resistance units RP(N) or M representing the number of series variable resistance units RS(M) and the number of each resistance.

[0060] Further, the synthesized resistance of the resistance circuit 100 can achieve the adjustment of the smallest resistance value by the fine adjustment of the series variable resistance unit including the resistance with the resistance value R 2max . Therefore, in the case where it is intended to adjust the resistance value with more minute accuracy, the resistance value of the resistance R2 in the series variable resistance unit RS can be increased.

[0061] In the existing resistance circuit, the adjustment accuracy is improved by reducing the resistance value of the resistance connected in parallel with the fuse, but the resistance value of the fuse and the resistance value of the resistance become close values, so an error from the target occurs in the change of the resistance value due to the fine adjustment. Further, the fuse is formed by ion implantation with a different dose from the polysilicon resistance or by salicidation, so the temperature dependence of the resistance value is different. Therefore, the temperature dependence of the resistance circuit is also deteriorated.

[0062] On the contrary, if it is the resistance circuit 100 having the above structure, in order to improve the adjustment accuracy of the resistance value, it is only necessary to increase the resistance value of the resistance within the series variable resistance unit RS. Regardless of how much the adjustment accuracy of the resistance value is increased, the resistance value of the fuse and the resistance value of the resistance do not become close, so the change of the resistance value does not cause a large error, and deterioration of the temperature dependence does not occur. Therefore, according to the resistance circuit 100, the adjustment accuracy of the resistance value of the resistance circuit 100 can be arbitrarily improved.

[0063] Figure 4 is a circuit diagram showing a structure example of a resistance circuit 100a as a specific example of the resistance circuit 100.

[0064] The resistance circuit 100a is a resistance circuit 100 satisfying the above formula (1) and configured with N=5 and M=5. In the resistance circuit 100a, the reference resistance R0 is configured to connect the resistance R01 in parallel with the resistance R02. The resistance value R0 of the reference resistance R0 obtained by connecting the resistance R01 in parallel with the resistance R02 is expressed as 1 / 2R.

[0065] Figure 5 is a circuit diagram showing a specific structure example of the series variable resistance group 10 (in the case where the parallel variable resistance unit is 5 (N=5)) in the resistance circuit 100a.

[0066] The resistance values of the resistances of the respective parallel variable resistance units in the series variable resistance group 10 are 4R in RP(1), 2R in RP(2), 1R in RP(3), 1 / 2R in RP(4), and 1 / 4R in RP(5), respectively.

[0067] Figure 6 is a circuit diagram showing a specific configuration example of the parallel variable resistance group 20 (a case where the number of series variable resistance units is five (M = 5)) in the resistance circuit 100a.

[0068] The resistance values of the resistances of the respective series variable resistance units in the parallel variable resistance group 20 are 1R in RS(1), 2R in RS(2), 4R in RS(3), 8R in RS(4), and 16R in RS(5), respectively.

[0069] In the resistance circuit 100a having the series variable resistance group 10 and the parallel variable resistance group 20 described above, if the left side of the above-described formula (1) is calculated, it is approximately 0.011, and the inequality of the above-described formula (1) is satisfied. Further, if the left side of the above-described formula (2) is calculated, it is approximately 0.14, and the inequality of the above-described formula (2) is also satisfied. Thus, the resistance circuit 100a is configured to be able to adjust the resistance value with high precision in the entire range from a high resistance value to a low resistance value, and further suppress an increase in circuit area.

[0070] Figure 7 and Figure 8 is a table showing the number of resistors in the resistance circuit 100 and the resistance circuit of the comparative example.

[0071] Here, the resistance circuit (not shown) of the comparative example is a resistance circuit configured to have the same number of 10 variable resistance units as the resistance circuit 100 and to have the same minimum adjustment precision as the resistance circuit 100a. Specifically, the resistance circuit of the comparative example is configured with respect to the resistance circuit 100a to have variable resistance units RcP(1) to RcP(10) corresponding to the parallel variable resistance units RP(1) to RP(10) instead of the series variable resistance group 10 and the parallel variable resistance group 20. Further, the resistance circuit of the comparative example is configured with respect to the resistance circuit 100a to have a reference resistor Rc0 whose resistance value is approximately equal to that of the combined resistance of the reference resistor R0 and the parallel variable resistance group 20 instead of the reference resistor R0.

[0072] In the resistance circuit 100a, the total number of resistors of the reference resistor R0, the respective parallel variable resistance units RP(1) to RP(5), and the respective series variable resistance units RS(1) to RS(5) is 46 (refer to Figure 7). On the other hand, in the resistance circuit of the comparative example, the total number of resistances of the reference resistance Rc0 and the variable resistance units RcP(1) to RcP(10) is 265 (refer to Figure 8

[0073] If the resistance circuit 100a is compared with the resistance circuit of the comparative example, the total number of resistances (46) of the resistance circuit 100a is approximately 17% of the total number of resistances (265) of the resistance circuit of the comparative example and can be reduced to approximately 1 / 6. In other words, the resistance circuit 100a can suppress the circuit area of the resistance elements to approximately 1 / 6 of the circuit area of the resistance elements of the resistance circuit of the comparative example, and thus can suppress an increase in the cost of the semiconductor chip.

[0074] Further, the smallest resistance value of the resistance circuit 100a is 1 / 4R. In contrast, the smallest resistance value of the resistance circuit of the comparative example is 1 / 128R. If the smallest resistance value (=1 / 128R) of the resistance circuit of the comparative example is compared with the smallest resistance value (=1 / 4R) of the resistance circuit 100a, the smallest resistance value of the resistance circuit of the comparative example is 1 / 32 times the smallest resistance value of the resistance circuit 100a and is very small, and thus the resistance value of the resistance circuit after trimming is likely to have a large error due to the resistance value of the fuse compared with the resistance circuit 100a. That is, the resistance circuit 100a can reduce the error of the resistance value of the resistance circuit 100a after trimming compared with the resistance circuit of the comparative example.

[0075] Next, the current detection circuit having the resistance circuit of the present embodiment will be described.

[0076] Figure 9 is a circuit diagram showing a configuration example of a current detection circuit 200 as an example of the current detection circuit of the present embodiment.

[0077] The current detection circuit 200 has a power supply terminal 3, a ground terminal 4, a sense output terminal 5, a resistance circuit 100 as an example of the resistance circuit of the present embodiment, a load 101, a sense transistor 110, an output transistor 111, a PMOS transistor 112, a gate drive circuit 120, and a current sense amplifier 121. Further, the current detection circuit 200 is configured to detect an output current Iout flowing in the output transistor 111 and supply a voltage converted by a current proportional to the detected output current Iout flowing in the resistance circuit 100 to the sense output terminal 5.

[0078] Next, the connection of the current detection circuit 200 will be described.

[0079] ​The source of the sensing transistor 110 is connected to the power supply terminal 3, the gate is connected to the output terminal of the gate drive circuit 120 and the gate of the output transistor 111, and the drain is connected to the source of the PMOS transistor 112 and the inverting input terminal (-) of the current sense amplifier 121. The source of the output transistor 111 is connected to the power supply terminal 3, and the drain is connected to one terminal of the load 101 and the non-inverting input terminal (+) of the current sense amplifier 121.

[0080] The other terminal of the load 101 is connected to the ground terminal 4. The output terminal of the current sense amplifier 121 is connected to the gate of the PMOS transistor 112. The drain of the PMOS transistor 112 is connected to the first terminal of the resistance circuit 100 and the sensing output terminal. The second terminal of the resistance circuit 100 is connected to the ground terminal 4.

[0081] Next, the operation of the current detection circuit 200 will be described.

[0082] The output current Iout flowing to the load 101 flows between the source and the drain of the output transistor 111. The current sense amplifier 121 controls the gate voltage of the PMOS transistor 112 in such a manner that the voltage of the inverting input terminal coincides with the voltage of the non-inverting input terminal.

[0083] The gate voltage of the PMOS transistor 112 is controlled in such a manner that the voltage of the inverting input terminal coincides with the voltage of the non-inverting input terminal, as a result of which the drain voltage of the sensing transistor 110 coincides with the drain voltage of the output transistor 111. The voltages of the source, the gate, and the drain of the sensing transistor 110 and the output transistor 111 coincide, and therefore the sensing current Isense proportional to the output current of the output transistor 111 flows in the sensing transistor 110.

[0084] The sensing current Isense flows in the resistance circuit 100 via the PMOS transistor 112, and the sensing voltage Vsense is generated across the resistance circuit 100 and output to the sensing output terminal 5 which is the output terminal. The sensing voltage Vsense is a voltage obtained by current-voltage conversion of the sensing current Isense by the resistance of the resistance circuit 100. Therefore, the sensing voltage Vsense is proportional to the output current Iout, and the sensing voltage Vsense is read from the outside, whereby the output current can be detected.

[0085] The accuracy of the current detection in the current detection circuit 200 is affected by manufacturing variations. As main factors, variations in the resistance value of the resistance circuit 100, relative variations in the characteristics of the sensing transistor 110 and the output transistor 111, and offset voltage between input terminals of the current sense amplifier affect the accuracy of the current detection. The current detection circuit 200, by having the resistance circuit 100, can suppress the circuit area and widen the current detection range, and compensate for variations in the resistance value, so it can generate a sensing voltage Vsense with good accuracy.

[0086] Further, the fine adjustment of the resistance circuit 100 is performed in a manner that offsets the effects of the relative variations in the characteristics of the sensing transistor 110 and the output transistor 111, and the offset voltage between input terminals of the current sense amplifier, so the accuracy of the current detection can be improved.

[0087] In addition, the present application is not limited to the above-described embodiments, and in the implementation stage, in addition to the above-described examples, it can be implemented in various other ways, and various omissions, substitutions, and changes can be made within the scope of the gist of the application.

[0088] For example, the connection order of the resistors and the fine adjustment elements can be swapped within the range that does not affect the synthesized resistance before and after the fine adjustment.

[0089] For example, between the first terminal 1 and the second terminal 2, in addition to the series variable resistance group 10 and the reference resistance R0, other resistance circuits with different resistance values made of the same unit resistance can be connected in series with the resistance circuit 100.

[0090] The fine adjustment elements T1[1] to T1[N] and the fine adjustment elements T2[1] to T2[M] are not limited to fuses. The fine adjustment elements T1[1] to T1[N] and the fine adjustment elements T2[1] to T2[M] can be elements that can switch from a connected state to a non-connected state, such as MOS (Metal Oxide Semiconductor; complementary metal oxide semiconductor) transistors.

[0091] The MOS transistors as the fine adjustment elements T1[1] to T1[N] and the fine adjustment elements T2[1] to T2[M] can be switched between conduction as the connected state and cutoff as the non-connected state by controlling the gate voltage. In addition, N, which represents the number of parallel variable resistance units RP(N), and M, which represents the number of series variable resistance units RS(M), do not necessarily have to be different numbers, but can be integers of 1 or more, and can be the same number.

[0092] The above-described embodiments and modifications thereof are included in the scope and gist of the application, and are included in the scope of the application described in the claims and equivalents thereof.

Claims

1. A resistor circuit connected between a first terminal and a second terminal, wherein the resistance value is variable, characterized in that, The resistor circuit includes: a reference resistor; a series variable resistor group connected in series with the reference resistor; and a parallel variable resistor group connected in parallel with the reference resistor. The series variable resistor group has N parallel variable resistor units connected in series with each other. Each of the N parallel variable resistor units has a resistor and a fine-tuning element connected in parallel with the resistor. The parallel variable resistor group has M series variable resistor units connected in parallel with each other. Each of the M series variable resistor units has a resistor and a fine-tuning element connected in series with the resistor. Both M and N are integers greater than or equal to 1. The resistance value of the reference resistor is set to R0, and the combined resistance of the reference resistor and the parallel variable resistor group is set to R. para Let R be the smallest resistance value among the resistance values ​​of the N parallel variable resistor units. 1min Let the largest resistance value among the resistance values ​​of the M series-connected variable resistor units be R. 2max Under these circumstances, the inequality in equation (1) holds. 【Mathematical Formula 1】 。 2. The resistor circuit according to claim 1, characterized in that, The resistance value of the reference resistor is set to R0, and the combined resistance of the reference resistor and the parallel variable resistor group is set to R. para Let R be the smallest resistance value among the resistance values ​​of the N parallel variable resistor units. 1min Under these circumstances, the inequality in equation (2) holds. 【Mathematical Formula 2】 。 3. The resistor circuit according to claim 1 or 2, characterized in that, The resistive circuit is formed of a semiconductor containing a polycrystalline silicon layer. The reference resistor, the resistance of the N parallel variable resistor units, and the resistance of the M series variable resistor units are formed from the same polycrystalline silicon layer contained in the semiconductor.

4. A current detection circuit that detects the current flowing through an output transistor, characterized in that, This current detection circuit has the following characteristics: The resistor circuit according to any one of claims 1 to 3; and The output transistor, The resistor circuit has a resistance value that is adjusted such that a current flows through the resistor circuit in proportion to the current flowing through the output transistor, and the resistor circuit supplies the voltage generated across the resistor circuit to the output terminal.

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