Reference current source

Abstract

To improve the accuracy of a reference current while suppressing an increase in circuit scale.SOLUTION: A reference current source 1 is provided with: a first semiconductor element 2 having a single diode-connected bipolar transistor; a second semiconductor element 3 having a plurality of diode-connected bipolar transistors connected in parallel; a resistor 4 converting a differential voltage ΔVbe into a current, the differential voltage being a difference between base-emitter voltages of the first semiconductor element 2 and the second semiconductor element 3; an amplifier 5 in which the first semiconductor element 2 is connected between one input terminal and ground and the resistor 4 and the second semiconductor element 3 are connected in series between the other input terminal and the ground; and a current mirror circuit 6 whose output current is controlled by an output of the amplifier 5. The reference current source 1 outputs a current corresponding to the current converted by the resistor 4 as a reference current IREF. The resistor 4 is a resistor having a temperature characteristic equivalent to that of the differential voltage ΔVbe.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a reference current source that outputs a reference current.

Background Art

[0002] The reference current source is often used for applications such as supplying a current flowing through a shunt resistor used in a current sensor, a reference current for an analog circuit in an A / D converter, etc. It is desirable that such a reference current source can output a constant reference current that does not fluctuate depending on temperature, that is, has no temperature characteristics. Patent Document 1 discloses a configuration for suppressing the temperature characteristics in a reference current source. In the following description, the configuration disclosed in Patent Document 1 will be referred to as the prior art.

[0003] The prior art is configured to generate a reference current Iref with substantially zero temperature characteristics based on the forward voltage VF1 of one first diode and the difference voltage dVF, which is the difference between the forward voltage VF1 and the forward voltage VF2 of a second diode with a changed current density, specifically, a plurality of second diodes connected in parallel. The difference voltage dVF is represented by the following formula (A). Here, k is the Boltzmann constant, T is the absolute temperature, q is the charge amount of an electron, and N is the number of second diodes connected in parallel.

[0004]

Equation

[0005] In this case, the first PMOS transistor for supplying current to the first diode, the second PMOS transistor for supplying current to the second diode, and the third PMOS transistor for outputting the reference current Iref constitute a current mirror circuit. Therefore, the currents I1 and I2 flowing through the first PMOS transistor P1 and the second PMOS transistor P2, respectively, are equal in value as shown in equation (B) below. In this case, the reference current Iref is expressed by equation (C) below. Here, I2A is the current flowing through the series circuit of the first resistor and the first diode, I2B is the current flowing through the second resistor connected in parallel to the above series circuit, R1 is the resistance value of the first resistor, and R2 is the resistance value of the second resistor.

[0006]

number

[0007] From the characteristics of the element, it is known that the differential voltage dVf has a positive temperature characteristic, and the forward voltage VF1 has a negative temperature characteristic, as expressed by equations (D) and (E) below.

[0008]

number

[0009] Based on these factors, the temperature characteristics of the reference current Iref can be expressed by equation (F) below.

[0010]

number

[0011] In conventional technology, as is clear from equation (F) above, by setting the constants N, R1, and R2 to arbitrary values, it is possible to cancel out the positive temperature characteristics of the differential voltage dVf and the negative temperature characteristics of the forward voltage VF1, thereby making the temperature characteristics of the reference current Iref approximately zero, in other words, canceling out the temperature characteristics. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 11-45125 [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] When considering the integration of a conventional design into an integrated circuit (IC), the first resistor is generally a non-silicide resistor, prioritizing area efficiency. IC stands for Integrated Circuit. Non-silicide resistors have a relatively small temperature characteristic, for example, around 0.01% / K. Therefore, when a non-silicide resistor is used as the first resistor, it is impossible to cancel the temperature characteristic using only the differential voltage dVf and the first resistor. For this reason, conventional designs require the addition of a fourth resistor connected in parallel with the first diode and a second resistor connected in parallel with the series circuit of the first resistor and the second diode, which inevitably increases the circuit size.

[0014] Furthermore, in conventional technology, as shown in equation (F) above, the value of the forward voltage VF1 affects the value of the reference current Iref. Therefore, if the absolute value of the forward voltage VF1 fluctuates, for example, due to stress applied to the IC package, it may become impossible to maintain good accuracy of the reference current Iref.

[0015] The present invention has been made in view of the above circumstances, and its purpose is to provide a reference current source that can improve the accuracy of the reference current while suppressing an increase in circuit size. [Means for solving the problem]

[0016] The reference current source according to claim 1 comprises: a first semiconductor element (2) consisting of one diode or one diode-connected bipolar transistor; a second semiconductor element (3) formed by connecting in parallel a plurality of diodes or a plurality of diode-connected bipolar transistors; a conversion resistor (4, 22) for converting a differential voltage, which is the difference between the forward voltage of each of the first semiconductor element and the second semiconductor element or the base-emitter voltage of each, into a current; an amplifier (5, 32) with the first semiconductor element connected between one input terminal and ground and the conversion resistor and the second semiconductor element connected in series between the other input terminal and ground; and a current mirror circuit (6, 33) whose output current is controlled by the output of the amplifier. The reference current source outputs, as a reference current, a current corresponding to the current converted by the conversion resistor. The conversion resistor is a resistor having a temperature characteristic similar to that of the differential voltage. The conversion resistor (22) consists of a combination of at least two resistors (22a, 22b) having temperature characteristics similar to those of the differential voltage. One of the two resistors has a temperature characteristic that is larger in the negative direction relative to the temperature characteristics of the differential voltage. The other of the two resistors has a temperature characteristic that is larger in the positive direction relative to the temperature characteristics of the differential voltage. One of the two resistors is a silicided poly resistor. The other of the two resistors is a silicided diffusion resistor.

[0017] According to such a configuration, it is possible to cancel out the positive temperature characteristic and the negative temperature characteristic only by the characteristics of the conversion resistor and the differential voltage, and the temperature characteristic of the reference current can be suppressed to a small value. Also, in the above configuration, there is no need to separately add two resistors to enable cancellation of the temperature characteristic as in the prior art, and the circuit scale can be suppressed accordingly. Furthermore, in the above configuration, although each forward voltage or each base-emitter voltage may vary due to stress, the differential voltage, which is the difference between them, varies extremely little due to stress. In the above configuration, since the reference current is determined only by the resistance value of the conversion resistor and the value of the differential voltage, it is possible to generate a reference current with little influence of variation due to stress. Thus, according to the above configuration, an excellent effect can be obtained in that the accuracy of the reference current can be improved while suppressing an increase in the circuit scale.

Brief Description of the Drawings

[0018] [Figure 1] Diagram schematically showing the configuration of the reference current source according to the first embodiment [Figure 2] Diagram schematically showing the configuration of the reference current source according to the second embodiment [Figure 3] FIG. 1 is a diagram showing an example of temperature characteristics of a reference current when the conversion resistor according to the second embodiment is constituted by one resistor and when it is constituted by a combination of two resistors. [Figure 4] FIG. 2 is a diagram schematically showing the configuration of a reference current source according to the third embodiment. [Figure 5] FIG. 3 is a diagram schematically showing the configuration of a reference current source according to the fourth embodiment. [Figure 6] FIG. 4 is a diagram schematically showing the configuration of a reference current source according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, a plurality of embodiments will be described with reference to the drawings. In each embodiment, substantially the same components are denoted by the same reference numerals and the description thereof will be omitted. (First Embodiment) Hereinafter, the first embodiment will be described with reference to FIG. 1.

[0020] As shown in FIG. 1, a reference current source 1 of the present embodiment is a circuit that generates and outputs a constant reference current IREF, and includes a first semiconductor element 2, a second semiconductor element 3, a resistor 4, an amplifier 5, and a current mirror circuit 6. The reference current source 1 is configured as an IC together with various circuits that are destinations of the output reference current IREF.

[0021] The first semiconductor element 2 is constituted by one PNP bipolar transistor. The collector of the first semiconductor element 2 is connected to the ground to which the reference potential of the circuit is applied, and is also connected to its base. That is, the bipolar transistor constituting the first semiconductor element 2 is diode-connected. The emitter of the first semiconductor element 2 is connected to node N1.

[0022] The second semiconductor element 3 has a configuration in which multiple PNP-type bipolar transistors are connected in parallel. In this embodiment, the number of bipolar transistors connected in parallel in the second semiconductor element 3 is assumed to be P, where P is a positive integer of 2 or more. In this case, each of the bipolar transistors constituting the first semiconductor element 2 and the multiple bipolar transistors constituting the second semiconductor element 3 are transistors of the same size.

[0023] The collector of the second semiconductor element 3 is connected to ground and also to its base. In other words, each of the multiple bipolar transistors constituting the second semiconductor element 3 is diode-connected. The emitter of the second semiconductor element 3 is connected to node N2 via resistor 4. Resistor 4 functions as a conversion resistor that converts the differential voltage ΔVbe, which is the difference between the base-emitter voltage Vbe1 of the first semiconductor element 2 and the base-emitter voltage Vbe2 of the second semiconductor element, into a current. The differential voltage ΔVbe is expressed by equation (1) below.

[0024]

number

[0025] Amplifier 5 has one input terminal, the inverting input terminal, connected to node N1. In other words, the first semiconductor element 2 is connected between one input terminal of amplifier 5 and ground. Amplifier 5 also has the other input terminal, the non-inverting input terminal, connected to node N2. In other words, the resistor 4 and the second semiconductor element 3 are connected in series between the other input terminal of amplifier 5 and ground. The output terminal of amplifier 5 is connected to node N3.

[0026] The current mirror circuit 6 is a circuit whose output current is controlled by the output of amplifier 5, and it comprises three transistors Q1, Q2, and Q3. Transistors Q1 to Q3 are all P-channel MOS transistors. The gates of transistors Q1 to Q3 are connected in common and also to node N3. The sources of transistors Q1 to Q3 are connected in common and also to power line 7, which supplies the circuit's power supply voltage VDD. The drain of transistor Q1 is connected to node N1, and the drain of transistor Q2 is connected to node N2. The drain of transistor Q3 is connected to node No, which is the output node of the reference current IREF.

[0027] In the above configuration, the operation of amplifier 5 causes equivalent collector currents to flow through the first semiconductor element 2 and the second semiconductor element 3, which have different area ratios. In other words, in the above configuration, the first semiconductor element 2 and the second semiconductor element 3 operate with different current densities. At this time, the voltage at the low-potential terminal of resistor 4 becomes voltage Vbe2 and the voltage at the high-potential terminal of resistor 4 becomes voltage Vbe1, resulting in a differential voltage ΔVbe between each terminal of resistor 4. Therefore, the differential voltage ΔVbe is converted into current by resistor 4.

[0028] The drain currents of each transistor Q1 to Q3 constituting the current mirror circuit 6 are corresponding to the current converted by resistor 4. Therefore, according to the reference current source 1 with the above configuration, the current corresponding to the current converted by resistor 4 is output as the reference current IREF. In this embodiment, resistor 4 is a resistor having temperature characteristics similar to those of the differential voltage ΔVbe, and specifically consists of a silicided polyresistor, a diffusion resistor, etc.

[0029] Next, we will explain the mechanism by which the temperature characteristics of the reference current IREF generated by the reference current source 1 in the above configuration are canceled. The temperature characteristics of the differential voltage ΔVbe and the temperature characteristics of the resistor 4 are expressed by equations (2) and (3) below, respectively. Here, T0 is an arbitrary temperature, ΔVbe0 is the differential voltage ΔVbe at temperature T0, R is the resistance value of resistor 4, R0 is the resistance value R at temperature T0, and α and β are temperature coefficients.

[0030]

number

[0031] In the above configuration, the reference current IREF is determined by the differential voltage ΔVbe and the resistance value R of resistor 4, as shown by equation (4) below. Based on equations (2) and (3) above, the reference current IREF can be expressed as shown in equation (5) below.

[0032]

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[0033] Here, the temperature coefficient α of the differential voltage ΔVbe is approximately 0.33% / K, as shown in equation (6) below. Also, the temperature coefficient β of resistor 4 is approximately 0.3% / K, although this depends on the type of silicided resistor.

[0034]

number

[0035] Thus, in the above configuration, the temperature coefficient α and the temperature coefficient β are approximately the same value. If the temperature coefficients α and β are the same value, the temperature-dependent term "α(T-T0)-β(T-T0)" in equation (6) above can be set to zero, and in that case, the reference current IREF becomes a current that does not fluctuate depending on the temperature. Therefore, with the above configuration, it is possible to cancel the temperature characteristics of the reference current IREF.

[0036] According to the embodiment described above, the following effects can be obtained. Generally, silicided resistors are rarely used because they have problems such as low sheet resistance, poor area efficiency, and large variability. However, silicided resistors have the advantage that their temperature characteristics are very close to those of the differential voltage ΔVbe. In the reference current source 1 of this embodiment, this point is taken into consideration, and a silicided resistor, that is, a resistor with temperature characteristics similar to those of the differential voltage ΔVbe, is used as the conversion resistor 4 that converts the differential voltage ΔVbe into current.

[0037] In this way, the reference current source 1 of this embodiment can cancel out the positive and negative temperature characteristics using only the characteristics of the resistor 4 and the differential voltage ΔVbe, thereby keeping the temperature characteristics of the reference current IREF small. Furthermore, the reference current source 1 of this embodiment does not require the addition of two separate resistors to enable temperature characteristic cancellation as in the conventional technology, and the circuit size can be reduced accordingly.

[0038] In the reference current source 1 of this embodiment, the voltages Vbe1 and Vbe2 may fluctuate due to the fluctuation of the reverse saturation currents of the first semiconductor element 2 and the second semiconductor element 3 caused by stress. However, according to the reference current source 1 of this embodiment, the differential voltage ΔVbe is determined by the difference between the voltages Vbe1 and Vbe2, so if there is no difference in the reverse saturation currents, the stress fluctuation becomes extremely small. In the reference current source 1 of this embodiment, since the reference current IREF is determined only by the resistance value R of the resistor 4 and the value of the differential voltage ΔVbe, it is possible to generate a reference current IREF that is less affected by fluctuations due to stress. Thus, according to this embodiment, the excellent effect of improving the accuracy of the reference current IREF while suppressing an increase in circuit size can be obtained.

[0039] (Second Embodiment) The second embodiment will be described below with reference to Figures 2 and 3. As shown in Figure 2, the reference current source 21 of this embodiment differs from the reference current source 1 of the first embodiment shown in Figure 1 in that it is equipped with a resistor 22 instead of resistor 4. The resistor 22 is composed of a combination of two resistors 22a and 22b, specifically a series circuit in which two resistors 22a and 22b are connected in series. Resistor 22a is a resistor having temperature characteristics similar to those of the differential voltage ΔVbe, and is specifically composed of a silicided polyresistor. Resistor 22b is a resistor having temperature characteristics similar to those of the differential voltage ΔVbe, and is specifically composed of a silicided diffusion resistor.

[0040] The temperature coefficient β1 of resistor 22a, one of the two resistors 22a and 22b, is approximately 0.28% / K, which is smaller than the temperature coefficient α of the differential voltage ΔVbe. In other words, resistor 22a has a temperature characteristic that is larger in the negative direction relative to the temperature characteristic of the differential voltage ΔVbe. On the other hand, the temperature coefficient β2 of resistor 22b, the other of the two resistors 22a and 22b, is approximately 0.335% / K, which is larger than the temperature coefficient α of the differential voltage ΔVbe. In other words, resistor 22b has a temperature characteristic that is larger in the positive direction relative to the temperature characteristic of the differential voltage ΔVbe.

[0041] Next, we will explain the mechanism by which the temperature characteristics of the reference current IREF generated by the reference current source 21 in the above configuration are canceled. The temperature characteristics of resistor 22 are expressed by equation (7) below. Here, R is the resistance value of resistor 22, R10 is the resistance value of resistor 22a at temperature T0, and R20 is the resistance value of resistor 22b at temperature T0.

[0042]

number

[0043] In the above configuration, the reference current IREF is determined by the differential voltage ΔVbe and the resistance value R of resistor 4, as shown by equation (4), similar to the first embodiment. Based on equation (7) above, the reference current IREF can be expressed as shown in equation (8) below.

[0044]

number

[0045] Here, by selecting resistors 22a and 22b so that equation (8) above can be transformed to eliminate the temperature-dependent term as shown in equation (9) below, the reference current IREF becomes a current that does not fluctuate with temperature. Therefore, with the above configuration, it is possible to accurately cancel the temperature characteristics of the reference current IREF.

[0046] As explained above, in the reference current source 21 of this embodiment, the resistor 22, which is a conversion resistor that converts the differential voltage ΔVbe into current, is composed of a combination of two resistors 22a and 22b that have temperature characteristics similar to those of the differential voltage ΔVbe. In this case, resistor 22a has a temperature characteristic that is larger in the negative direction relative to the temperature characteristics of the differential voltage ΔVbe, and resistor 22b has a temperature characteristic that is larger in the positive direction relative to the temperature characteristics of the differential voltage ΔVbe. With such a configuration, the effect of canceling out the temperature characteristics can be further enhanced compared to when the conversion resistor is composed of a single silicided resistor. The reason for this is as follows.

[0047] In other words, when the conversion resistor is made of a single silicided resistor, if the temperature characteristics of that single silicided resistor and the temperature characteristics of the differential voltage ΔVbe do not perfectly match, the temperature characteristics corresponding to the difference between them will appear in the reference current IREF. For example, when the conversion resistor is made of a single silicided polyresistor, resistor 22a, the reference current IREF will have a positive temperature characteristic that increases as the temperature increases, as shown by the dotted line in Figure 3.

[0048] Furthermore, for example, if the conversion resistor is configured with a single silicided diffusion resistor, resistor 22b, the reference current IREF will have a negative temperature characteristic, decreasing as the temperature increases, as shown by the dashed line in Figure 3. In contrast, as in this embodiment, if the conversion resistor, resistor 22, is configured with a combination of two silicided resistors 22a and 22b, the reference current IREF will have almost no temperature-dependent fluctuation, as shown by the solid line in Figure 3, and the temperature characteristic that appears when the conversion resistor is configured with a single resistor 22a or 22b can be almost completely canceled out.

[0049] Furthermore, in this embodiment, the conversion resistor 22 is configured as a series circuit of two resistors 22a and 22b. This has the advantage of allowing the resistance value of resistor 22 to be reduced compared to the case where the conversion resistor 22 is configured as a parallel circuit of two resistors 22a and 22b.

[0050] (Third embodiment) The third embodiment will be described below with reference to Figure 4. As shown in Figure 4, the reference current source 31 of this embodiment differs from the reference current source 1 of the first embodiment shown in Figure 1 in that it is equipped with an amplifier 32 instead of amplifier 5, and a current mirror circuit 33 instead of current mirror circuit 6.

[0051] Amplifier 32 is configured as a chopper amplifier with a chopping function, and is supplied with a clock signal fcp as its operating clock. Amplifier 32 modulates the input signal by alternately inverting its polarity using the clock signal fcp, converting the input signal bandwidth into the clock frequency bandwidth. In amplifier 32, the amplified signal is demodulated back to the original input signal bandwidth by alternately inverting its polarity again using the clock signal fcp.

[0052] The current mirror circuit 33 includes three transistors Q31, Q32, and Q33 in addition to the configuration of the current mirror circuit 6. Transistors Q31 to Q33 are all P-channel MOS transistors. The gates of transistors Q31 to Q33 are connected in common. The drain of transistor Q1 is connected to node N1 via the source-drain connection of transistor Q31.

[0053] The drain of transistor Q2 is connected to node N2 via the source-drain junction of transistor Q32. The drain of transistor Q3 is connected to node No, which is the output node of the reference current IREF, via the source-drain junction of transistor Q33. In this way, the current mirror circuit 33 is configured in a cascode configuration.

[0054] Offset components caused by factors such as transistor mismatch have temperature characteristics, and these offset components may reduce the accuracy of the reference current IREF. Therefore, in the reference current source 31 of this embodiment, a chopper amplifier with a chopping function is used as the amplifier 32. With this configuration, the offset components are removed by the chopping function of the amplifier 32, thereby further improving the accuracy of the reference current IREF.

[0055] (Fourth Embodiment) The fourth embodiment will be described below with reference to Figure 5. As shown in Figure 5, the reference current source 41 of this embodiment differs from the reference current source 1 of the first embodiment shown in Figure 1 in that it is equipped with a current mirror circuit 33 similar to that of the third embodiment instead of the current mirror circuit 6, and a dynamic element matching circuit 42 is added. In the drawings such as Figure 5 and the following description, dynamic element matching may be abbreviated as DEM.

[0056] The DEM circuit 42 is composed of multiple switches, and by switching these switches on and off, the variation component of the current mirror circuit 33 can be corrected. The DEM circuit 42 is positioned between each of the transistors Q1 to Q3 and each of the transistors Q31 to Q33 in the current mirror circuit 33. The DEM circuit 42 can also be positioned between each of the transistors Q31 to Q33 and each of the nodes N1, N2, and No.

[0057] The reference current source 41 in this embodiment includes a DEM circuit 42 that corrects the variation component of the current mirror circuit 33. With this configuration, the degree of agreement of each output current of the current mirror circuit 33 is improved by the DEM circuit 42, thereby further improving the accuracy of the reference current IREF.

[0058] (Fifth embodiment) The fifth embodiment will be described below with reference to Figure 6. As shown in Figure 6, the reference current source 51 of this embodiment differs from the reference current source 41 of the fourth embodiment shown in Figure 5 in that it is equipped with an amplifier 32 similar to that of the third embodiment instead of amplifier 5. With this configuration, the offset component is removed by the chopping function of amplifier 32, and the degree of agreement of each output current of the current mirror circuit 33 is improved by the DEM circuit 42, thereby further improving the accuracy of the reference current IREF.

[0059] (Other embodiments) It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and can be arbitrarily modified, combined, or expanded without departing from its essence. The numerical values ​​and other figures shown in each of the above embodiments are illustrative examples and are not limiting. The conversion resistor is not limited to resistor 4, which is a silicide-converted resistor; any resistor with temperature characteristics similar to the differential voltage ΔVbe may be used, such as a wiring resistor.

[0060] In the first embodiment, the configuration was such that equivalent collector currents flowed through the first semiconductor element 2 and the second semiconductor element 3, which have different area ratios. However, instead, the configuration can be such that different collector currents flow through the first semiconductor element and the second semiconductor element, which have the same area ratio.

[0061] In the first embodiment, the first semiconductor element 2 consisted of a single diode-connected PNP bipolar transistor, and the second semiconductor element 3 consisted of multiple diode-connected PNP bipolar transistors connected in parallel. However, instead, the following configurations can also be used. Specifically, the first semiconductor element 2 consists of a single diode-connected NPN bipolar transistor, and the second semiconductor element 3 consists of multiple diode-connected NPN bipolar transistors connected in parallel. Alternatively, the first semiconductor element consists of a single diode, and the second semiconductor element consists of multiple diodes connected in parallel. In this case, the conversion resistor converts the differential voltage, which is the difference between the forward voltages of the first and second semiconductor elements, into current.

[0062] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

[0063] This disclosure includes, in addition to the invention described in the claims, the following inventions: [1] A first semiconductor element (2) consisting of one diode or one diode-connected bipolar transistor, A second semiconductor element (3) comprising multiple diodes or multiple diode-connected bipolar transistors connected in parallel, A conversion resistor (4, 22) that converts the differential voltage, which is the difference between the forward voltages or base-emitter voltages of the first semiconductor element and the second semiconductor element, into a current, An amplifier (5, 32) in which the first semiconductor element is connected between one input terminal and ground, and the conversion resistor and the second semiconductor element are connected in series between the other input terminal and ground, A current mirror circuit (6, 33) whose output current is controlled by the output of the amplifier, Equipped with, The current corresponding to the current converted by the aforementioned conversion resistor is output as the reference current. The aforementioned conversion resistor is a reference current source that has temperature characteristics similar to those of the differential voltage. [2] The aforementioned conversion resistor is composed of a silicided resistor, as described in [1], the reference current source. [3] The conversion resistor (22) consists of a combination of at least two resistors (22a, 22b) having temperature characteristics similar to those of the differential voltage. One of the two resistors has a temperature characteristic that is large in the negative direction with respect to the temperature characteristic of the differential voltage. The reference current source according to claim [1] or [2], wherein the other of the two resistors has a temperature characteristic that is larger in the positive direction with respect to the temperature characteristic of the differential voltage. [4] The amplifier (32) is a reference current source according to any one of claims [1] to [3], having a chopping function. [5] moreover, A reference current source according to any one of [1] to [4], comprising a dynamic element matching circuit (42) for correcting the variation component of the current mirror circuit (33). [Explanation of Symbols]

[0064] 1, 21, 31, 41, 51...Reference current source, 2...First semiconductor element, 3...Second semiconductor element, 4, 22...Resistor, 22a, 22b...Resistor, 5, 32...Amplifier, 6, 33...Current mirror circuit, 42...Dynamic element matching circuit.

Claims

1. A first semiconductor element (2) consisting of one diode or one diode-connected bipolar transistor, A second semiconductor element (3) comprising multiple diodes or multiple diode-connected bipolar transistors connected in parallel, A conversion resistor (4, 22) that converts the differential voltage, which is the difference between the forward voltages or base-emitter voltages of the first semiconductor element and the second semiconductor element, into a current, An amplifier (5, 32) in which the first semiconductor element is connected between one input terminal and ground, and the conversion resistor and the second semiconductor element are connected in series between the other input terminal and ground in this order, A current mirror circuit (6, 33) whose output current is controlled by the output of the amplifier, Equipped with, The current corresponding to the current converted by the aforementioned conversion resistor is output as the reference current. The aforementioned conversion resistor is a resistor having temperature characteristics similar to those of the differential voltage. The conversion resistor (22) consists of a combination of at least two resistors (22a, 22b) having temperature characteristics similar to those of the differential voltage. One of the two resistors has a temperature characteristic that is large in the negative direction with respect to the temperature characteristic of the differential voltage. Of the two resistors mentioned above, the other resistor has a temperature characteristic that is larger in the positive direction relative to the temperature characteristic of the differential voltage. One of the two resistors mentioned above is a silicided poly resistor. The other of the two resistors mentioned above is a reference current source, which is a silicide-converted diffusion resistor.

2. The reference current source according to claim 1, wherein the amplifier (32) has a chopping function.

3. moreover, The reference current source according to claim 1, further comprising a dynamic element matching circuit (42) for correcting the variation component of the current mirror circuit (33).

4. moreover, The reference current source according to claim 2, further comprising a dynamic element matching circuit (42) for correcting the variation component of the current mirror circuit (33).

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