Temperature compensation circuit and semiconductor integrated circuit using the same

Abstract

The present invention provides a temperature compensation circuit for generating a temperature-compensated current and a semiconductor integrated circuit using the same. The temperature compensation circuit includes: a first PTAT current source having a first emitter area ratio and generating a first current having a first temperature coefficient proportional to absolute temperature; a second PTAT current source having a second emitter area ratio and generating a second current having a second temperature coefficient proportional to absolute temperature; an adjustment circuit for adjusting the current generated by the first PTAT current source; and a difference circuit for outputting the difference between the current adjusted by the adjustment circuit and the current generated by the second PTAT current source.

Description

Technical Field

[0001] The present invention relates to a temperature compensation circuit for generating a temperature-compensated current, and more particularly to a temperature compensation circuit using two proportional-to-absolute-temperature (PTAT) current sources and a semiconductor integrated circuit using the same. Background Art

[0002] In semiconductor devices such as memory or logic circuits, a voltage that is temperature-compensated according to the operating temperature is usually generated, and the circuit is operated using the temperature-compensated voltage to maintain the reliability of the circuit. In a memory circuit, when reading data, if the read current decreases due to temperature changes, the read margin decreases and accurate data cannot be read. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2021-82094) discloses a voltage generating circuit that generates a reference voltage V REF Temperature dependent voltage V PTAT Compare and select the reference voltage V according to the comparison result REF Or temperature dependent voltage V PTAT Any one of them, thereby generating a voltage with high reliability.

[0003] In analog circuit design, the temperature coefficient (TCO) of constant current circuits or constant current sources often presents a challenge. For example, an oscillator includes a delay circuit to determine the oscillation cycle time (period). To avoid the voltage dependency of the delay time caused by fluctuations in the power supply voltage, a constant current circuit is sometimes used in this delay circuit. However, the temperature coefficient of the constant current circuit causes the delay time to fluctuate with temperature, thus affecting the oscillator cycle time. Summary of the Invention

[0004] The temperature compensation circuit of the present invention comprises: a first circuit, which uses transistors with a first emitter area or diodes with a number ratio equivalent to the first emitter area to generate a first current, wherein the first current has a first temperature coefficient proportional to the absolute temperature; a second circuit, which uses transistors with a second emitter area or diodes with a number ratio equivalent to the second emitter area to generate a second current, wherein the second current has a second temperature coefficient proportional to the absolute temperature; and a differential circuit, which outputs a differential current between the first current and the second current.

[0005] A semiconductor integrated circuit of the present invention includes: the temperature compensation circuit described above; and a voltage generating circuit that generates a voltage based on a differential current output from the temperature compensation circuit.

[0006] According to the present invention, a current that has been temperature compensated with high accuracy can be obtained by generating a difference between currents having different temperature coefficients proportional to absolute temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a diagram showing an example of a typical PTAT;

[0008] Figure 2 (A) and Figure 2 (B) means Figure 1 A graph showing the relationship between the current flowing in the PTAT and the temperature;

[0009] Figure 3 A diagram showing the structure of a temperature compensation circuit according to an embodiment of the present invention;

[0010] Figure 4 (A) and Figure 4 (B) is a diagram showing an example of an adjustment circuit according to an embodiment of the present invention;

[0011] Figure 5 is a graph showing the relationship between the output current Idiff and the temperature according to an embodiment of the present invention;

[0012] Figure 6 A diagram showing a modified example of the adjustment circuit of the temperature compensation circuit according to the embodiment of the present invention;

[0013] Figure 7 A diagram showing another modified example of the adjustment circuit of the temperature compensation circuit according to the embodiment of the present invention;

[0014] Figure 8 FIG. 1 is a diagram showing a modified example of the PTAT current source of the temperature compensation circuit according to the embodiment of the present invention.

[0015] Explanation of symbols

[0016] 10: PTAT current source

[0017] 20: Current mirror circuit

[0018] 100, 100A, 100B: Temperature compensation circuit

[0019] 110: First PTAT current source

[0020] 110A: First PTAT current source

[0021] 112: Operational Amplifier

[0022] 120: Second PTAT current source

[0023] 120A: Second PTAT current source

[0024] 130, 130A, 130B: Adjustment circuit

[0025] 140: Differential Circuit

[0026] I1, I2, I A , I B : Current

[0027] Idiff: differential current (output current)

[0028] KI A , K'I B :Adjusted current (current)

[0029] N1, N2: transistors

[0030] Node1, Node2: nodes

[0031] P1, P2, P3, P4, P5, P6, P10, P11: PMOS transistors (transistors)

[0032] P51~P5 n :transistor

[0033] Q1, Q2: NPN bipolar transistors (NPN bipolar transistors, bipolar transistors, transistors)

[0034] Q3, Q4: NPN bipolar transistors (bipolar transistors, transistors)

[0035] Q: Connecting nodes

[0036] R, R A 、R B :resistance

[0037] SW1, SW2~SWn: switches

[0038] TRC: Adjustment Code

[0039] VDD: supply voltage DETAILED DESCRIPTION

[0040] The embodiment of the present invention will be described in detail with reference to the accompanying drawings. The temperature compensation circuit of the present invention can be used in semiconductor integrated circuits such as voltage generation circuits that generate reference voltages, oscillation circuits, and other logic circuits.

[0041] Figure 1This diagram shows the structure of a typical PTAT current source. PTAT current source 10 includes a current mirror circuit 20 that supplies currents I1 and I2 to first and second current paths, respectively. It also includes an NPN bipolar transistor Q1 connected to the first current path, an NPN bipolar transistor Q2 connected to the second current path, and a resistor R connected between transistor Q2 and ground (GND). Current mirror circuit 20 is controlled so that the output current I1 equals the output current I2. Furthermore, the emitter area ratio of diode-connected transistors Q1 and Q2 is 1:n (n represents the emitter area ratio), resulting in a current density of transistor Q1 that is n times that of transistor Q2.

[0042] Figure 2 (A) represents Figure 1 The graph shows the relationship between current I1 (= I2) flowing through the PTAT current source and temperature. The vertical axis represents current (uA) and the horizontal axis represents temperature. The graph also shows the relationship between current and temperature for emitter area ratios n of 1:2, 1:4, and 1:8. Current I1 has a positive temperature coefficient with respect to absolute temperature, and its magnitude is generally proportional to the emitter area ratio n. However, the temperature coefficient varies slightly with different emitter area ratios, so the ratios shown are approximate and not exact. Figure 2 (B) shows Figure 2 Graph (A) shows the relationship between the emitter area ratio and the temperature coefficient in the temperature range of -45° C. to 52.5° C. As the emitter area ratio increases, the temperature coefficient decreases.

[0043] In this embodiment, a temperature-compensated current is generated by utilizing two PTAT current sources and by taking the difference between their currents. As described above, when emitter area ratios differ, the temperature coefficients of the two current sources differ slightly. However, the difference between the two currents can produce a current that is virtually invariant with temperature. In a preferred embodiment, the currents of one or both of the two PTAT current sources are proportionally adjustable, thereby making the temperature coefficient of the differential current approach zero, thereby generating a highly accurate temperature-compensated current.

[0044] Next, the temperature compensation circuit of this embodiment will be described in detail. Figure 3 FIG1 is a diagram showing the structure of a temperature compensation circuit according to an embodiment of the present invention. The temperature compensation circuit 100 of this embodiment includes a first PTAT current source 110, a second PTAT current source 120, an adjustment circuit 130, and a differential circuit 140. The first PTAT current source 110 generates a current I having a temperature coefficient proportional to the absolute temperature. A The second PTAT current source 120 generates a current I having a temperature coefficient proportional to the absolute temperature.B , the adjustment circuit 130 adjusts the current I generated by the first PTAT current source 110 A The size is adjusted to K times, generating the adjusted current KI A , the differential circuit 140 outputs the adjusted current KI A The current I generated by the second PTAT current source 120 B The difference.

[0045] The first PTAT current source 110 includes a first current path and a second current path between the supply voltage VDD and GND. The first current path includes a PMOS transistor P1 and an NPN bipolar transistor Q1 connected in series. The second current path includes a PMOS transistor P2, an NPN bipolar transistor Q2, and a resistor R connected in series. A The transistor P1 and the transistor P2 form a current mirror with a mirror ratio of 1 (m=1), which flows the current I to the first current path and the second current path. A The current source functions as a resistor. In the bipolar transistors Q1 and Q2, the bases are commonly connected to the first current path, that is, diode-connected. The emitter area ratio n of the bipolar transistors Q1 and Q2 is, for example, 1:2. A There is no particular limitation, and for example, it may be composed of a resistor having positive temperature characteristics or a resistor made of a semiconductor material having negative temperature characteristics.

[0046] Like the first PTAT current source 110, the second PTAT current source 120 includes a first current path and a second current path between the supply voltage VDD and the supply voltage GND. The first current path includes a PMOS transistor P3 and an NPN bipolar transistor Q3 connected in series, and the second current path includes a PMOS transistor P4, an NPN bipolar transistor Q4, and a resistor R connected in series. B The transistor P3 and the transistor P4 form a current mirror with a mirror ratio of 1 (m=1), which flows the current I B The current source functions as a resistor. In the bipolar transistors Q3 and Q4, the bases are commonly connected to the first current path, that is, diode-connected. The emitter area ratio n of the transistors Q3 and Q4 is, for example, 1:4. B It is composed of a resistor R A The same resistance value (R B =R A ).

[0047] The adjustment circuit 130 adjusts the current I generated by the first PTAT current source 110 AIn this example, the adjustment circuit 130 includes a PMOS transistor P5 that forms a current mirror with the PMOS transistor P1 and the PMOS transistor P2, and adjusts the mirror ratio K (m=K, K is a value greater than 1) of the transistor P5. The method for adjusting the mirror ratio K is not particularly limited. For example, the adjustment circuit 130 includes logic for adjusting the mirror ratio K based on an adjustment code (Trim Code, TRC) supplied from the outside or an adjustment code TRC pre-stored in a storage unit such as a memory. For example, the adjustment circuit 130 is as follows Figure 4 (A) includes a plurality of transistors P51 to P5 connected in parallel with n transistors P5. n Switches SW1 to SWn are connected in series to each of these transistors, and switches SW1 to SWn are selectively turned on according to the adjustment code TRC. As a result, the total drain current of the transistors after turning on becomes the adjusted current KI A Thus, a current I is generated at the drain of transistor P5. A K times the mirror current (mirror current) K×I A .

[0048] The differential circuit 140 includes a first current path and a second current path between the supply voltage VDD and the supply voltage GND. The first current path includes an NMOS transistor N1 connected in series with the transistor P5 of the adjustment circuit 130. The current KI from the transistor P5 A The second current path includes a PMOS transistor P6 that forms a current mirror with the transistor P3 and transistor P4 of the second PTAT current source and has a mirror ratio of 1 (m=1), and an NMOS transistor N2 connected in series with the PMOS transistor P6. The current I B The gates of transistors N1 and N2 are connected to the first current path, forming a current mirror circuit. B and current KI A The differential current Idiff(I B -KI A ) is output to the outside from the connection node Q between the transistor P6 and the transistor N2.

[0049] Current I A Based on the emitter area ratio of the NPN bipolar transistor, it is approximately I B / 2, but the current I A The temperature coefficient (Tco) of the current I B The temperature coefficient (Tco) is larger. If the current KI A Temperature gradient relative to absolute temperature and current I BBy selecting the mirror ratio K of the adjustment circuit 130 in a manner of the same degree, the temperature dependency of the differential current Idiff can be made as close to zero as possible.

[0050] Figure 5 The graph shows the relationship between the differential current Idiff and the temperature when the mirror ratio K is changed in the actual temperature compensation circuit 100. When the mirror ratio K is reduced, the current I B The influence of is relatively large, so the output current Idiff moves in the positive increasing direction as the temperature rises. When the mirror ratio K is increased, the current KI A The influence of is relatively large, so the output current Idiff moves in the direction of current reduction as the temperature rises. Therefore, as long as the range of change in the positive direction and the range of change in the negative direction (for example Figure 5 By selecting the mirror ratio K (in the range represented by S in FIG), the temperature variation of the output current Idiff can be made close to zero.

[0051] As described above, according to the temperature compensation circuit of this embodiment, by utilizing the difference in temperature coefficients of the two PTAT current sources, a temperature-compensated constant current with higher accuracy than conventional circuits can be obtained.

[0052] In the above embodiment, NPN bipolar transistors Q1, Q2, Q3, and Q4 are used in the first and second PTAT current sources 110 and 120. However, these transistors can be replaced with diode-connected PNP bipolar transistors. Furthermore, the NPN bipolar transistors can be replaced with diodes. In this case, the emitter area ratio is equivalent to the ratio of the number of diodes connected in parallel.

[0053] In the embodiment described above, the emitter area ratio of the first PTAT current source 110 is set to 1:2, and the emitter area ratio of the second PTAT current source 120 is set to 1:4. However, the emitter area ratios described above are merely examples, and other emitter area ratios may also be used. For example, the emitter area ratio of the first PTAT current source 110 may be set to 1:4, and the emitter area ratio of the second PTAT current source 120 may be set to 1:8.

[0054] In the embodiment, the current I generated by the first PTAT current source 110 is shown. A The current I generated by the second PTAT current source 120 can also be adjusted. B In this case, the adjustment circuit 130 can adjust the mirror ratio of the transistor P6, which forms a current mirror with the transistors P3 and P4, to m=K', and adjust the adjusted current K'I BProvides a second current path to the differential circuit 140. In addition, the adjustment circuit 130 can also adjust the current I A and current I B Both, and the adjusted current KI A and current K'I B A first current path and a second current path are provided to the differential circuit 140 .

[0055] In the embodiment shown, the current I is supplied from the transistor P6 to the second current path of the differential circuit 140. B For example, the transistor P6 is not necessary. For example, the current I generated by the transistor P4 of the second PTAT current source 120 may also be B The current is directly supplied to the differential circuit 140. The configuration of the differential circuit 140 is an example, and other current differential circuits may also be used.

[0056] Next, refer to Figure 6 , a modified example of the adjustment circuit of the temperature compensation circuit of this embodiment is described. In the embodiment, the adjustment circuit 130 is a structure including a PMOS transistor P5 constituting a current mirror, and in this example, as shown in FIG. Figure 6 As shown, the first PTAT current source 110 includes an adjustment circuit 130A. Figure 3 The structure is the same.

[0057] In the first PTAT current source 110, the mirror ratio of the transistor P2 constituting the current mirror circuit is adjusted to K (m=K). The adjustment circuit 130A adjusts the mirror ratio K of the transistor P2 according to the adjustment code TRC (for example, Figure 4 (A) as shown in the following example), and the adjusted mirror current KI A The current is supplied to the differential circuit 140. By removing the transistor P5 constituting the current mirror, the structure of the temperature compensation circuit 100A is simplified, thereby achieving space saving.

[0058] In addition, when adjusting the current I B In the case of the same method as above, the mirror ratio of the transistor P4 constituting the current mirror circuit in the second PTAT current source 120 can be adjusted to K', and the adjusted mirror current K'I B A second current path is provided to the differential circuit 140 .

[0059] Next, refer to Figure 7 , another variation of the adjustment circuit of the temperature compensation circuit of this embodiment is described. In the temperature compensation circuit 110B of this variation, the adjustment circuit 130B changes the resistance R of the first PTAT current source 110. Aand / or the resistance R of the second PTAT current source 120 B The resistance value is used to adjust the current I proportional to the absolute temperature. A and current I B size.

[0060] Resistor R A / Resistor R B The adjustment circuit 130B changes the resistance R according to the adjustment code TRC. A / Resistor R B The resistance value can be adjusted by any method. For example, the adjustment circuit 130B can be as follows: Figure 4 (B) shows the resistor R A The multiple tap positions of the switches SW1, SW2 to SWn are connected, and the switches SW1 to SWn are selectively turned on according to the adjustment code TRC to turn on the resistor R A A portion of the resistor is short-circuited, thereby changing the resistance value.

[0061] In this example, the adjustment circuit 130B is a resistor R A / Resistor R B However, if it is necessary to make the temperature change of the differential current Idiff close to zero, the adjustment circuit 130B can also be adjusted in the resistor R A / Resistor R B While adjusting Figure 3 or Figure 6 As shown, the mirror ratio K is adjusted simultaneously.

[0062] Next, refer to Figure 8 , a modified example of the PTAT current source of the temperature compensation circuit of this embodiment is described. The first PTAT current source 110 and the second PTAT current source 120 are current mirror circuits of PMOS transistors to control the current I A , current I B , can be replaced by an operational amplifier current mirror. The first PTAT current source 110A and the second PTAT current source 120A include a PMOS transistor P10, a PMOS transistor P11 (with the same structure as transistor P10) and an operational amplifier 112. The PMOS transistor P10 and the PMOS transistor P11 are connected to the supply voltage VDD. The operational amplifier 112 connects the node Node1 to the non-inverting input terminal (+), connects the node Node2 to the inverting input terminal (-), and connects the output terminal to the gates of the transistors P10 and P11. The operational amplifier 112 controls the gate voltages of the transistors P10 and P11 so that the voltages of the nodes Node1 and Node2 become equal, thereby allowing equal currents I to flow through the first current path and the second current path. ACurrent I B By using the operational amplifier 112, compared to the previous embodiment, it is possible to generate a current I with high precision and equal in the first current path and the second current path. A / Current I B .

[0063] While the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

Claims

1. A temperature compensation circuit comprising: a first circuit, using transistors having a first emitter area or diodes having a number ratio equivalent to the first emitter area ratio to generate a first current, wherein the first current has a first temperature coefficient proportional to absolute temperature; a second circuit, generating a second current using transistors having a second emitter area ratio or diodes having a number ratio equivalent to the second emitter area ratio, the second current having a second temperature coefficient proportional to absolute temperature, wherein a first emitter area ratio of the first circuit is different from a second emitter area ratio of the second circuit, the first current is proportional to the first emitter area ratio, and the second current is proportional to the second emitter area ratio; as well as a differential circuit, outputting a differential current between the first current and the second current, wherein the differential circuit comprises: a first transistor comprising a first terminal, a second terminal, and a control terminal, wherein the first terminal of the first transistor is coupled to a first supply voltage, and the control terminal of the first transistor is coupled to the second circuit; a second transistor comprising a first terminal, a second terminal, and a control terminal, wherein the first terminal of the second transistor is coupled to the first circuit, the second terminal of the second transistor is coupled to a second supply voltage, and the control terminal of the second transistor is coupled to the first terminal of the second transistor, wherein the first supply voltage is greater than the second supply voltage; and a third transistor including a first terminal, a second terminal, and a control terminal, wherein the first terminal of the third transistor is coupled to the second terminal of the first transistor, the second terminal of the third transistor is coupled to the second supply voltage, and the control terminal of the third transistor is coupled to the control terminal of the second transistor, wherein the differential current is output from the first terminal of the third transistor.

2. The temperature compensation circuit according to claim 1, wherein: The first circuit and the second circuit each include a fourth transistor, a fifth transistor and an operational amplifier. One end of the fourth transistor and the fifth transistor is connected to the first supply voltage, The non-inverting input terminal of the operational amplifier is connected to the first node, the inverting input terminal of the operational amplifier is connected to the second node, and the output terminal of the operational amplifier is commonly connected to the gates of the fourth transistor and the fifth transistor. The operational amplifier controls the gate voltages of the fourth transistor and the fifth transistor so that the voltage of the first node becomes equal to the voltage of the second node.

3. The temperature compensation circuit according to claim 1, further comprising: An adjusting component adjusts the magnitude of the first current or the second current.

4. The temperature compensation circuit according to claim 3, wherein: The adjusting component adjusts the magnitude of the first current or the second current through a current mirror circuit.

5. The temperature compensation circuit according to claim 3, wherein: The adjusting component adjusts the resistance value of the resistor.

6. The temperature compensation circuit according to claim 5, wherein: The adjustment component includes a plurality of switches, and each of the plurality of switches is selectively turned on according to an adjustment code to change the resistance value of the resistor.

7. The temperature compensation circuit according to claim 1, wherein: The first circuit includes a first current mirror circuit as a current source for supplying the first current, and the second circuit includes a second current mirror circuit as a current source for supplying the second current.

8. The temperature compensation circuit according to claim 7, further comprising: An adjusting component adjusts the mirror ratio of the first current mirror circuit or the second current mirror circuit.

9. The temperature compensation circuit according to claim 5, wherein: The adjustment component adjusts the mirror ratio of the first current mirror circuit according to an adjustment code, and the adjusted first current is supplied to the differential circuit.

10. The temperature compensation circuit according to claim 7, further comprising: The adjustment component includes a fourth transistor that forms a current mirror with the first current mirror circuit or the second current mirror circuit, and adjusts the mirror ratio of the fourth transistor.

11. The temperature compensation circuit according to claim 10, wherein: The adjustment component includes a plurality of fourth transistors connected in parallel to form a current mirror with the first current mirror circuit or the second current mirror circuit, and a plurality of switches connected in series to each of the plurality of fourth transistors. The mirror ratio of the fourth transistor is adjusted by selectively turning on each of the plurality of switches according to an adjustment code.

12. The temperature compensation circuit according to claim 10, wherein: The differential circuit includes a first current path and a second current path, The first current path includes the second transistor connected in series with the fourth transistor of the adjustment component and is supplied with current from the fourth transistor. The second current path includes the first transistor forming a current mirror with the second current mirror circuit and a third transistor connected in series with the first transistor, and is supplied with current from the first transistor. The gate of the second transistor and the gate of the third transistor are commonly connected to the first current path to form a current mirror.

13. The temperature compensation circuit according to claim 1, wherein: The transistor is an NPN or PNP bipolar transistor.

14. A semiconductor integrated circuit comprising: The temperature compensation circuit according to any one of claims 1 to 13; and The voltage generating circuit generates a voltage based on the differential current output from the temperature compensation circuit.

15. A temperature compensation circuit comprising: a first proportional-to-absolute-temperature (PTAT) circuit, using transistors with a first emitter area or diodes with a number ratio equivalent to the first emitter area and a first resistor to generate a first current, wherein the first current has a first temperature coefficient proportional to the absolute temperature; A second PTAT circuit generates a second current using transistors having a second emitter area or diodes having a number ratio equivalent to the second emitter area and a second resistor, wherein the second current has a second temperature coefficient proportional to the absolute temperature; as well as a differential circuit configured to output a differential current between the first current and the second current, wherein a first emitter area ratio of the first PTAT circuit is different from a second emitter area ratio of the second PTAT circuit, the first current is proportional to the first emitter area ratio, and the second current is proportional to the second emitter area ratio, wherein the first temperature coefficient decreases when the first emitter area ratio increases, and the second temperature coefficient decreases when the second emitter area ratio increases; as well as an adjusting component for adjusting the magnitude of the first current so that when the second emitter area of the second PTAT circuit is larger than the first emitter area of the first PTAT circuit, the temperature gradient of the first current relative to absolute temperature is the same as the temperature gradient of the second current relative to absolute temperature. 16 . The temperature compensation circuit of claim 15 , wherein the first resistor and the second resistor have the same resistance value. 17 . The temperature compensation circuit according to claim 15 , wherein the adjustment component adjusts the magnitude of the first current or the second current.

18. The temperature compensation circuit according to claim 15, wherein: The first PTAT circuit includes a first current mirror circuit as a current source for supplying the first current, and the second PTAT circuit includes a second current mirror circuit as a current source for supplying the second current.

19. The temperature compensation circuit according to claim 15, wherein: The first PTAT circuit includes a first current mirror circuit as a current source for supplying the first current, and the second PTAT circuit includes a second current mirror circuit as a current source for supplying the second current, and The adjustment component adjusts the mirror ratio of the first current mirror circuit or the mirror ratio of the second current mirror circuit.

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