Reference voltage supply circuit

Abstract

The reference voltage supply circuit comprises a first transistor, a second transistor, a first resistor and a second resistor. The first transistor is coupled to a high voltage level terminal. The second transistor is coupled to a low voltage level terminal. The first resistor and the first transistor are coupled to a reference node to provide a reference voltage. The second resistor is coupled between the first resistor and the second transistor. The first resistor and the second resistor include variable resistors.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a reference voltage supply circuit, and in particular to a reference voltage supply circuit designed to avoid the reference voltage being affected by temperature variation. BACKGROUND

[0002] A general bandgap voltage reference circuit is composed of a plurality of transistors. However, if the transistors are manufactured by different processes or the transistors have different parameters due to process drift in the same process, the reference voltage generated by the bandgap voltage reference circuit will be affected by temperature variation. SUMMARY

[0003] In view of the deficiencies of the prior art, one of the purposes of the present disclosure (but not limited to) is to provide a reference voltage supply circuit to improve the deficiencies of the prior art.

[0004] In some embodiments, the reference voltage supply circuit includes a first transistor, a second transistor, a first resistor, and a second resistor. The first transistor is coupled to a high voltage level end. The second transistor is coupled to a low voltage level end. The first resistor and the first transistor are coupled to a reference node to provide a reference voltage. The second resistor is coupled between the first resistor and the second transistor. The first resistor and the second resistor include variable resistors.

[0005] The technical means embodied by the embodiments of the present disclosure can improve at least one of the shortcomings of the prior art. The reference voltage supply circuit of the present disclosure uses variable resistors to adjust the slope of the temperature coefficient voltage with temperature variation, so that the reference voltage supply circuit of the present disclosure maintains zero temperature coefficient, thereby avoiding the reference voltage being affected by temperature variation.

[0006] The features, implementations, and technical effects of the present disclosure are described in detail below with reference to the preferred embodiments and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 A schematic diagram of a reference voltage supply circuit according to some embodiments of the present disclosure;

[0008] Figure 2 A schematic diagram of a reference voltage and temperature according to some embodiments of the present disclosure;

[0009] Figure 3 A schematic diagram of a positive temperature coefficient voltage, a negative temperature coefficient voltage, and a temperature according to some embodiments of the present disclosure;

[0010] Figure 4 A schematic diagram of a reference voltage supply circuit according to some embodiments of the present disclosure;

[0011] Figure 5 a reference voltage versus temperature diagram plotted according to some embodiments of the present disclosure;

[0012] Figure 6 a positive temperature coefficient voltage, a negative temperature coefficient voltage versus temperature diagram plotted according to some embodiments of the present disclosure;

[0013] Figure 7 a reference voltage supply circuit diagram plotted according to some embodiments of the present disclosure;

[0014] Figure 8 a reference voltage versus temperature diagram plotted according to some embodiments of the present disclosure; and

[0015] Figure 9 a positive temperature coefficient voltage, a negative temperature coefficient voltage versus temperature diagram plotted according to some embodiments of the present disclosure.

[0016] Symbol Explanation

[0017] 100, 400, 700: reference voltage supply circuit

[0018] k1, k2: coefficient

[0019] M1: first transistor

[0020] M2: second transistor

[0021] MUX1: first multiplexer

[0022] MUX2: second multiplexer

[0023] N1-Nn: node

[0024] Nref: reference node

[0025] R1-Rn: resistance

[0026] Th: high voltage level end

[0027] Tl: low voltage level end

[0028] V1-Vn: voltage

[0029] Vc: negative temperature coefficient voltage

[0030] Vg1, Vg2: control end voltage

[0031] Vgs1, Vgs2: cross voltage

[0032] Vp: positive temperature coefficient voltage

[0033] Vref: reference voltage

[0034] S1, S2: selection signal

[0035] S+: slope of positive temperature coefficient voltage

[0036] S-: slope of negative temperature coefficient voltage DETAILED DESCRIPTION

[0037] All words used herein are used in their normal meaning. The definitions of the above words in the commonly used dictionaries are hereby incorporated into the disclosure of the present disclosure as an example of the use of any of the words discussed herein in the present disclosure, and should not limit the scope and meaning of the present disclosure. Similarly, the present disclosure is not limited only to the various embodiments shown in the specification.

[0038] As used herein, "coupled" or "connected" can mean two or more elements are in direct physical or electrical contact with each other, or can mean that two or more elements are not in direct contact with each other, but can still cooperate or interact with each other in some way. As used herein, the term "circuit" can be a device that includes at least one transistor and / or at least one passive element connected in a certain way to process a signal.

[0039] As used herein, the term "and / or" includes any combination of one or more of the associated items. In this document, the use of the words first, second, and third, etc., is used to describe and distinguish various elements. Therefore, the first element in this document can also be referred to as the second element without departing from the true meaning of the present disclosure. For easy understanding, similar elements in the drawings will be designated by the same reference numerals.

[0040] To avoid the problem that the reference voltage in the prior art is affected by temperature changes, the present disclosure proposes a reference voltage supply circuit, which will be described in detail as follows.

[0041] Figure 1 A schematic diagram of a reference voltage supply circuit 100 according to some embodiments of the present disclosure is shown. As shown, the reference voltage supply circuit 100 includes a first transistor M1, a second transistor M2, a first resistor R1, and a second resistor R2.

[0042] In circuit design, the first transistor M1 is coupled to a high voltage level end Th, and the second transistor M2 is coupled to a low voltage level end Tl. In addition, the first resistor R1 and the first transistor M1 are coupled to a reference node Nref to provide a reference voltage Vref. The second resistor R2 is coupled between the first resistor R1 and the second transistor M2. The first resistor R1 and the second resistor R2 include variable resistors. The reference voltage Vref provided by the reference voltage supply circuit 100 of the present disclosure is as follows:

[0043]

[0044] Please refer to Formula 1, where Vref is the reference voltage, Vgs1 is the voltage across the first transistor M1, Vgs2 is the voltage across the second transistor M2, R1 is the first resistor, and R2 is the second resistor. Please refer to Formula 1. Figure 2 as well as Figure 3 Assuming Figure 2 The reference voltage Vref is in a state where the slope S+ of the positive temperature coefficient voltage is less than the slope |S-| of the negative temperature coefficient voltage. This disclosure allows for the enhancement of the reference voltage Vref by adjusting either the first resistor R1 or the second resistor R2. Figure 3 The slope of the positive temperature coefficient voltage Vp, thus, Figure 2 The reference voltage Vref can be restored to a state where the slope S+ of the positive temperature coefficient voltage is equal to the slope |S-| of the negative temperature coefficient voltage, so that the reference voltage supply circuit 100 of this disclosure maintains a zero temperature coefficient, thereby avoiding the influence of temperature changes on the reference voltage Vref.

[0045] Please see Figure 1 In some embodiments, the first transistor M1 includes a first terminal, a control terminal, and a second terminal. The first terminal of the first transistor M1 (as shown above) is coupled to the high voltage level terminal Th, the second terminal of the first transistor M1 (as shown below) is coupled to the first terminal of the first resistor R1 (as shown above) and is coupled to the reference node Nref, and the control terminal of the first transistor M1 is coupled to the second terminal of the first resistor R1 (as shown below) and is coupled to the first node N1.

[0046] In some embodiments, the first end of the second resistor R2 (as shown above) is coupled to the control terminal of the first transistor M1 and the second end of the first resistor R1 (as shown below) to the first node N1.

[0047] In some embodiments, the second transistor M2 includes a first terminal, a control terminal, and a second terminal. The first terminal (as shown above) of the second transistor M2 is coupled to the second terminal (as shown below) of the second resistor R2 at the second node N2. The control terminal of the second transistor M2 is coupled to the first terminal (as shown above) of the second transistor M2 and the second terminal (as shown below) of the second resistor R2 at the second node N2. The second terminal (as shown below) of the second transistor M2 is coupled to the low voltage level terminal T1.

[0048] Figure 4 This is a schematic diagram of a reference voltage supply circuit 400 according to some embodiments of the present disclosure. As shown, the reference voltage supply circuit 400 includes a first transistor M1, a second transistor M2, a first resistor R1, and a second resistor R2.

[0049] In the circuit design, the first transistor M1 is coupled to the high-voltage level terminal Th, and the second transistor M2 is coupled to the low-voltage level terminal Tl. Furthermore, the first resistor R1 is coupled to the first transistor M1 at the reference node Nref to provide the reference voltage Vref. The second resistor R2 is coupled between the first resistor R1 and the second transistor M2. Both the first resistor R1 and the second resistor R2 include variable resistors. The reference voltage Vref provided by the reference voltage supply circuit 400 of this disclosure is formulated as follows:

[0050]

[0051] Please refer to Formula 2, where Vref is the reference voltage, Vgs1 is the voltage across the first transistor M1, Vgs2 is the voltage across the second transistor M2, R1 is the first resistor, and R2 is the second resistor. Please refer to Formula 2. Figure 5 as well as Figure 6 Assuming Figure 5 The reference voltage Vref is in a state where the slope S+ of the positive temperature coefficient voltage is greater than the slope |S-| of the negative temperature coefficient voltage. This disclosure allows for the reduction of this slope by adjusting either the first resistor R1 or the second resistor R2. Figure 6 The slope of the positive temperature coefficient voltage Vp, thus, Figure 5 The reference voltage Vref can be restored to a state where the slope S+ of the positive temperature coefficient voltage is equal to the slope |S-| of the negative temperature coefficient voltage, so that the reference voltage supply circuit 400 of this disclosure maintains a zero temperature coefficient, thereby avoiding the influence of temperature changes on the reference voltage Vref.

[0052] Please see Figure 4 In some embodiments, the first transistor M1 includes a first terminal, a control terminal, and a second terminal. The first terminal of the first transistor M1 (as shown above) is coupled to the high voltage level terminal Th, the second terminal of the first transistor M1 (as shown below) is coupled to the first terminal of the first resistor R1 (as shown above) and is coupled to the reference node Nref, and the control terminal of the first transistor M1 is coupled to the first terminal of the second resistor R2 (as shown below) and is coupled to the first node N1.

[0053] In some embodiments, the second end of the second resistor R2 (as above) is coupled to the second end of the first resistor R1 (as below) at the second node N2.

[0054] In some embodiments, the second transistor M2 includes a first terminal, a control terminal, and a second terminal. The first terminal (as shown above) of the second transistor M2 is coupled to the control terminal of the first transistor M1 and the first terminal (as shown below) of the second resistor R2 at the first node N1. The control terminal of the second transistor M2 is coupled to the second terminal (as shown below) of the first resistor R1 and the second terminal (as shown above) of the second resistor R2 at the second node N2. The second terminal (as shown below) of the second transistor M2 is coupled to the low voltage level terminal T1.

[0055] Please see Figure 7 In some embodiments, the reference voltage supply circuit 700 includes a plurality of resistors R1 to Rn, which are connected in series in pairs to a plurality of nodes N1 to Nn, for example, resistors R1 and R2 are connected in series in node N1.

[0056] In some embodiments, the first transistor M1 includes a first terminal, a control terminal, and a second terminal. The first terminal (as shown above) of the first transistor M1 is coupled to the high voltage level terminal Th, and the second terminal (as shown below) of the first transistor M1 is coupled to the first terminal (as shown above) of the resistors R1 of the plurality of resistors R1 to Rn to the reference node Nref.

[0057] In some embodiments, the reference voltage supply circuit 700 further includes a first multiplexer MUX1, which includes a first terminal and a second terminal. The first terminal (e.g., the left terminal) of the first multiplexer MUX1 is coupled to the control terminal of the first transistor M1, and the second terminal (e.g., the right terminal) of the first multiplexer MUX1 is selectively coupled to one of a plurality of nodes N1 to Nn. In some embodiments, the second terminal (e.g., the right terminal) of the first multiplexer MUX1 is coupled to one of the target nodes of the plurality of nodes N1 to Nn according to a first selection signal S1. In some embodiments, the reference voltage supply circuit 700 of this disclosure can adjust the node to which the control terminal of the first transistor M1 is to be connected through the first multiplexer MUX1, and the voltage formula of the control terminal of the first transistor M1 is as follows:

[0058] Vg1=Vk1......Formula 3

[0059] Please refer to Formula 3. Vg1 is the voltage at the control terminal of the first transistor M1. Vk1 depends on the node to which the first multiplexer MUX1 is connected. For example, if the first multiplexer MUX1 is connected to node N1, then Vk1 is V1. If the first multiplexer MUX1 is connected to node N2, then Vk1 is V2. And so on, with k1 ranging from 1 to N.

[0060] In some embodiments, the first end (as shown above) of resistor Rn of the plurality of resistors R1 to Rn is coupled to one of the plurality of resistors R1 to Rn.

[0061] In some embodiments, the second transistor M2 includes a first terminal, a control terminal, and a second terminal. The first terminal of the second transistor M2 (as shown above) is coupled to one of a plurality of nodes (as shown in node Nn) and the second terminal of the resistor Rn (as shown below). The second terminal of the second transistor M2 (as shown below) is coupled to a low voltage level terminal Tl.

[0062] In some embodiments, the reference voltage supply circuit 700 further includes a second multiplexer MUX2, which includes a first terminal and a second terminal. The first terminal (e.g., the left terminal) of the second multiplexer MUX2 is coupled to the control terminal of the second transistor M2, and the second terminal (e.g., the right terminal) of the second multiplexer MUX2 is selectively coupled to one of a plurality of nodes N1 to Nn. In some embodiments, the second terminal (e.g., the right terminal) of the second multiplexer MUX2 is coupled to one of the target nodes of the plurality of nodes N1 to Nn according to a second selection signal S2. In some embodiments, a plurality of resistors R1 to Rn may be selectively coupled to the control terminals of the first transistor M1 and the second transistor M2 through a plurality of nodes N1 to Nn to form different resistance values. In some embodiments, the resistance values ​​of each of the plurality of resistors R1 to Rn are the same, or the resistance values ​​of each of the plurality of resistors R1 to Rn are different. In some embodiments, the reference voltage supply circuit 700 of this disclosure may use the second multiplexer MUX2 to adjust the node to which the control terminal of the second transistor M2 is to be connected, and the voltage formula of the control terminal of the second transistor M2 is as follows:

[0063] Vg2=Vk2......Formula 4

[0064] Please refer to Formula 4. Vg2 is the voltage at the control terminal of the second transistor M2. Vk2 depends on the node to which the second multiplexer MUX2 is connected. For example, if the second multiplexer MUX2 is connected to node N1, then Vk2 is V1. If the second multiplexer MUX2 is connected to node N2, then Vk2 is V2. And so on, with k2 ranging from 1 to N.

[0065] The reference voltage Vref provided by the reference voltage supply circuit 700 of this disclosure is formulated as follows:

[0066]

[0067] Please refer to Equation 5, where Vref is the reference voltage, Vgs1 is the voltage across the first transistor M1, Vgs2 is the voltage across the second transistor M2, and k1 and k2 depend on the nodes connected to the first multiplexer MUX1 and the second multiplexer MUX2. Please refer to Equation 5. Figure 8 as well as Figure 9 Assuming Figure 8 The reference voltage Vref is in a state where the slope S+ of the positive temperature coefficient voltage is greater than the slope |S-| of the negative temperature coefficient voltage. This disclosure can be achieved by adjusting the voltage Vref. The ratio, in order to reduce Figure 9 The slope of the positive temperature coefficient voltage Vp, thus, Figure 8The reference voltage Vref can be restored to a state where the slope S+ of the positive temperature coefficient voltage is equal to the slope |S-| of the negative temperature coefficient voltage, so that the reference voltage supply circuit 700 of this disclosure maintains a zero temperature coefficient, thereby avoiding the influence of temperature changes on the reference voltage Vref.

[0068] Furthermore, assuming Figure 8 The reference voltage Vref is in a state where the slope S+ of the positive temperature coefficient voltage is less than the slope |S-| of the negative temperature coefficient voltage. This disclosure can be achieved by adjusting the voltage Vref. The ratio, to increase Figure 9 The slope of the positive temperature coefficient voltage Vp, thus, Figure 8 The reference voltage Vref can be restored to a state where the slope S+ of the positive temperature coefficient voltage is equal to the slope |S-| of the negative temperature coefficient voltage, so that the reference voltage supply circuit 700 of this disclosure maintains a zero temperature coefficient, thereby avoiding the influence of temperature changes on the reference voltage Vref.

[0069] In some embodiments, please refer to Figure 1 , Figure 4 as well as Figure 7 The first transistor M1 and the second transistor M2 can be metal-oxide-semiconductor field-effect transistors (MOSFETs). In some embodiments, the first transistor M1 and the second transistor M2 can be N-type MOSFETs or P-type MOSFETs. In some embodiments, the first terminal can be the drain, the control terminal can be the gate, and the second terminal can be the source.

[0070] It should be noted that this disclosure does not imply... Figures 1 to 9 The embodiments shown are limited and are merely illustrative of one implementation of this disclosure to facilitate understanding of the technology. The patent scope of this disclosure should be determined by the scope of the invention application. Modifications and refinements made by those skilled in the art to the embodiments of this disclosure without departing from the concept of this disclosure still fall within the scope of the invention patent application of this disclosure.

[0071] In summary, the technical means embodied in the embodiments of this disclosure can improve at least one of the shortcomings of the prior art. The reference voltage supply circuit of this disclosure uses a variable resistor to adjust the slope of the temperature coefficient voltage change with temperature, so that the reference voltage supply circuit of this disclosure maintains a zero temperature coefficient, thereby avoiding the influence of temperature changes on the reference voltage.

[0072] Although the embodiments of this disclosure are described above, these embodiments are not intended to limit this disclosure. Those skilled in the art can make changes to the technical features of this disclosure based on its express or implied content. All such changes may fall within the scope of patent protection sought by this disclosure. In other words, the scope of patent protection of this disclosure shall be determined by the scope of the patent application in this specification.

Claims

1. A reference voltage supply circuit, comprising: a first transistor coupled to a high voltage level terminal; a second transistor coupled to a low voltage level terminal; a first resistor coupled with the first transistor at a reference node to provide a reference voltage; and a second resistor coupled between the first resistor and the second transistor, wherein the first resistor and the second resistor comprise variable resistors.

2. The reference voltage supply circuit of claim 1, wherein the first transistor comprises: a first terminal coupled to the high voltage level terminal; a second terminal coupled with a first terminal of the first resistor at the reference node; and a control terminal coupled with a second terminal of the first resistor at a first node; wherein a first terminal of the second resistor, the control terminal of the first transistor, and the second terminal of the first resistor are coupled at the first node.

3. The reference voltage supply circuit of claim 2, wherein the second transistor comprises: a first terminal coupled with a second terminal of the second resistor at a second node; a control terminal coupled with the first terminal of the second transistor and the second terminal of the second resistor at the second node; and a second terminal coupled to the low voltage level terminal; wherein a first resistance value of the first resistor is decreased or a second resistance value of the second resistor is increased, thereby increasing a slope of a positive temperature coefficient voltage with respect to temperature.

4. The reference voltage supply circuit of claim 1, wherein the first transistor comprises: a first terminal coupled to the high voltage level terminal; a second terminal coupled with a first terminal of the first resistor at the reference node; and a control terminal coupled with a first terminal of the second resistor at a first node; wherein a second terminal of the second resistor and a second terminal of the first resistor are coupled at a second node.

5. The reference voltage supply circuit of claim 4, wherein the second transistor comprises: a first terminal coupled with the control terminal of the first transistor and the first terminal of the second resistor at the first node; and a second terminal coupled to the low voltage level terminal; a control terminal coupled to the second terminal of the first resistor and the second terminal of the second resistor at the second node; wherein a first resistance value of the first resistor is decreased or a second resistance value of the second resistor is increased, thereby decreasing a slope of a positive temperature coefficient voltage with respect to temperature.

6. The reference voltage supply circuit of claim 1, further comprising: a plurality of resistors coupled in series two-by-two at a plurality of nodes, wherein the plurality of resistors comprise the first resistor and the second resistor; wherein the first transistor comprises: a first terminal coupled to the high voltage level terminal; a second terminal coupled with a first terminal of the first resistor of the plurality of resistors at the reference node; and a control terminal.

7. The reference voltage supply circuit of claim 6, further comprising: a first multiplexer comprising: a first terminal coupled to the control terminal of the first transistor; and a second terminal selectively coupled to one of the plurality of nodes, wherein the second terminal of the first multiplexer is coupled to a first target node of the plurality of nodes according to a first selection signal. ​ ​ 8. The reference voltage supply circuit of claim 7, wherein a first end of the second resistor of the plurality of resistors is coupled to one of the plurality of nodes. wherein the second transistor comprises: a first end coupled to a second end of the second resistor and one of the plurality of nodes; a control end; and a second end coupled to the low voltage level end.

9. The reference voltage supply circuit of claim 8, further comprising: a second multiplexer comprising: a first end coupled to the control end of the second transistor; and a second end selectively coupled to one of the plurality of nodes, wherein the second end of the second multiplexer is coupled to a second target node of the plurality of nodes according to a second selection signal.

10. The reference voltage supply circuit of claim 1, wherein the first transistor and the second transistor comprise the same type of transistor, wherein the high voltage level end comprises a power supply voltage end, and wherein the low voltage level end comprises a ground end.

Images