Operational amplifier structure and integrated circuit

Abstract

The present disclosure relates to the field of semiconductor device design, and in particular to an operational amplifier structure and an integrated circuit. The operational amplifier structure comprises an operational amplifier and a compensation module. The compensation module comprises: a compensation circuit, which is coupled to the operational amplifier, and is configured to, on the basis of an initial compensation current, generate a pair of compensation currents, wherein the pair of compensation currents are used for reducing operational amplifier mismatch of the operational amplifier; and a compensation current source, which is coupled to the compensation circuit to provide the initial compensation current, wherein the initial compensation current is obtained by synthesizing a constant current and a temperature-controlled current, and the magnitude of the temperature-controlled current is negatively correlated with the temperature. By allowing the magnitude of the compensation current to change along with a temperature change, the compensation effect of the compensation current on the operational amplifier mismatch is improved.

Description

Operational amplifier structure and integrated circuits

[0001] Cross-references

[0002] This disclosure claims priority to Chinese patent application No. 202410482744.5, entitled "Operational Amplifier Structure and Integrated Circuit", filed on April 22, 2024, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to the field of semiconductor device design, and in particular to an operational amplifier structure and integrated circuit. Background Technology

[0004] Operational amplifier offset (op-amp) generally refers to the non-zero voltage deviation generated at the output terminal of an operational amplifier (op-amp) under normal operating conditions. This non-zero voltage deviation is mainly due to parameter mismatch of the op-amp's internal components, the influence of external environmental factors (such as temperature, humidity, and pressure), and manufacturing limitations.

[0005] For example, for the voltage source structure shown in Figure 1, its output voltage Vout = (Vref + ΔVos) * (R1 + R0) / R0, and for the current source structure shown in Figure 2, its output current Iout = (Vref + ΔVos) / R2, where ΔVos is the equivalent input offset voltage of the op-amp. It can be seen that op-amp offset has a significant impact on the output results of current and voltage sources, and reducing op-amp offset is crucial in circuits with high performance requirements such as voltage and current sources.

[0006] Summary of the Invention

[0007] This disclosure provides an operational amplifier structure and integrated circuit, which improves the compensation effect of the compensation current on operational amplifier misalignment by setting the magnitude of the compensation current to vary with temperature.

[0008] One embodiment of this disclosure provides an operational amplifier structure, including an operational amplifier and a compensation module. The compensation module includes: a compensation circuit coupled to the operational amplifier, configured to generate a compensation current pair based on an initial compensation current, the compensation current pair being used to reduce operational amplifier mismatch; and a compensation current source coupled to the compensation circuit to provide an initial compensation current. The initial compensation current is synthesized from a constant current and a temperature-controlled current, and the magnitude of the temperature-controlled current is negatively correlated with the temperature.

[0009] By applying an initial compensation current that is negatively correlated with temperature to the compensation module, the magnitude of the compensation current for operational amplifier offset in the compensation module is negatively correlated with temperature. When the external temperature changes, the compensation current for completing the mismatch compensation in the transistor saturation region changes in the same direction as the compensation current provided by the compensation module, so that the operational amplifier offset can still be well compensated after being compensated at room temperature and after temperature changes.

[0010] The compensation current source includes: a first operational amplifier, whose non-inverting input terminal is used to receive a reference voltage, and whose output terminal is connected to the gate of a first transistor; the source of the first transistor is connected to the first terminal of a first resistor and to the negative input terminal of the first operational amplifier, and the second terminal of the first resistor is grounded; a second operational amplifier, whose non-inverting input terminal is used to receive a temperature-controlled voltage, and whose output terminal is connected to the gate of a second transistor; the source of the second transistor is connected to the first terminal of a second resistor and to the negative input terminal of the second operational amplifier, and the second terminal of the second resistor is grounded; wherein, the drain of the first transistor is used to generate a constant current, the drain of the second transistor is used to generate a temperature-controlled current, and the drains of the first transistor and the drain of the second transistor are connected to synthesize and generate an initial compensation current.

[0011] In some embodiments, the first resistor and the second resistor are configured as resistors with adjustable resistance values.

[0012] In some embodiments, the compensation current source further includes: a voltage generation circuit coupled to a second operational amplifier, configured to generate a temperature-controlled voltage based on the temperature of the operational amplifier structure, wherein the magnitude of the temperature-controlled voltage is negatively correlated with the temperature of the operational amplifier structure.

[0013] In some embodiments, the voltage generating circuit includes: a temperature-controlled current source, with an input terminal for receiving power supply voltage and an output terminal for outputting temperature-controlled voltage; and a temperature-controlled transistor, with its emitter connected to the output terminal of the temperature-controlled current source and its base connected to the collector and the collector grounded.

[0014] In some embodiments, the voltage generation circuit includes: a temperature-controlled current source, with an input terminal for receiving a power supply voltage and an output terminal for outputting a temperature-controlled voltage; a temperature-controlled MOSFET, with its gate connected to its drain and its drain connected to the output terminal of the temperature-controlled current source, and its source grounded; wherein the temperature-controlled MOSFET is configured to operate in the subthreshold region.

[0015] In some embodiments, the compensation circuit includes: a master control transistor, the source of which receives a power supply voltage, the gate of which is connected to the drain, and the drain of which is used to receive an initial compensation current; a first temperature-controlled transistor group, including a plurality of first temperature-controlled transistors, wherein the source of each first temperature-controlled transistor is connected to the source of the master control transistor, the gate of which is connected to the gate of the master control transistor, and the drains of the plurality of first temperature-controlled transistors are interconnected to generate a first compensation current; a second temperature-controlled transistor group, including a plurality of second temperature-controlled transistors, wherein the source of each second temperature-controlled transistor is connected to the source of the master control transistor, the gate of which is connected to the gate of the master control transistor, and the drains of the plurality of second temperature-controlled transistors are interconnected to generate a second compensation current; wherein the first compensation current and the second compensation current constitute a compensation current pair.

[0016] In some embodiments, the operational amplifier includes: a first-stage amplifier circuit configured to amplify input signals at the non-inverting input and the negative-inverting input of the operational amplifier to generate an initial output signal; a second-stage amplifier circuit connected to the first-stage amplifier circuit configured to amplify the initial output signal to generate an output signal; wherein a compensation current pair is used to compensate for the magnitude of the initial output signal.

[0017] In some embodiments, the first-stage amplifier circuit includes: a first switching transistor, the source of which receives a power supply voltage and the gate of which receives a first switching signal; a first P-type transistor, the source of which is connected to the drain of the first switching transistor and the gate of which serves as the non-inverting input terminal of the operational amplifier; a second P-type transistor, the source of which is connected to the drain of the first switching transistor and the gate of which serves as the non-inverting input terminal of the operational amplifier; the drains of the first and second P-type transistors are used to output an initial output signal; the second-stage amplifier circuit includes: a third P-type transistor, the source of which receives a power supply voltage; a fourth P-type transistor, the source of which receives a power supply voltage and the gate of the third P-type transistor; and a fifth P-type transistor, the source of which is connected to the drain of the third P-type transistor and the drain of which is connected to the gate of the third P-type transistor. The sixth P-type transistor has its source connected to the drain of the fourth P-type transistor and its gate connected to the gate of the fifth P-type transistor. Its drain serves as the output terminal of the operational amplifier. The first N-type transistor has its drain connected to the drain of the fifth P-type transistor and its source connected to the drain of the first P-type transistor and receiving a compensation current pair. Its gate is used to receive a second switching signal. The second N-type transistor has its drain connected to the drain of the sixth P-type transistor and its source connected to the drain of the second P-type transistor and receiving a compensation current pair. Its gate is connected to the gate of the first N-type transistor. The third N-type transistor has its drain connected to the source of the first N-type transistor, and its source is grounded. Its gate is used to receive a third switching signal. The fourth N-type transistor has its drain connected to the source of the second N-type transistor, and its source is grounded. Its gate is connected to the gate of the third N-type transistor.

[0018] Another embodiment of this disclosure provides an integrated circuit in which the operational amplifier structure provided in the above embodiment is disposed. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrative descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this disclosure or the conventional technology, the drawings required in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 is a schematic diagram of a voltage source;

[0021] Figure 2 is a schematic diagram of a current source;

[0022] Figure 3 is a schematic diagram of an operational amplifier;

[0023] Figure 4 is a schematic diagram of a structure that generates compensation current;

[0024] Figure 5 is a schematic diagram of the operational amplifier structure provided in an embodiment of this disclosure;

[0025] Figure 6 is a schematic diagram of the structure of a compensation current source provided in an embodiment of this disclosure;

[0026] Figure 7 is a schematic diagram of a voltage generation circuit provided in an embodiment of the present disclosure;

[0027] Figure 8 is a schematic diagram of another voltage generation circuit provided in an embodiment of the present disclosure;

[0028] Figure 9 is a schematic diagram of the operational amplifier and compensation circuit in an operational amplifier structure provided in an embodiment of this disclosure. Detailed Implementation

[0029] There are many methods in the industry to eliminate the effects of ΔVos. For example, the size of the op-amp is made larger, sacrificing area to reduce the impact of ΔVos; there are also ways to provide compensation current to offset ΔVos, but since ΔVos varies not only with the process but also with external environmental factors such as power supply voltage and temperature, the effect of offsetting ΔVos by compensation current is not good.

[0030] In voltage or current source circuits where high precision is required, the requirements for operational amplifier offset compensation are very strict. In addition to using large-area operational amplifiers to reduce the impact of operational amplifier offset, current compensation is often used to further reduce operational amplifier offset.

[0031] In one example, referring to Figure 3, which is a schematic diagram of an operational amplifier, the operational amplifier with offset compensation function includes: operational amplifier 10 and compensation module 11. The compensation module 11 compensates for the mismatch between the input terminals Vin+ and Vin- of operational amplifier 10 based on the compensation current Ipp and the number of conducting compensation branches.

[0032] Specifically, the first temperature-controlled transistor group 21 compensates for the non-inverting input terminal Vin+ of the operational amplifier. The first temperature-controlled transistor group 21 conducts N1 branches based on transistors, and the compensation current for the non-inverting input terminal Vin+ of the operational amplifier is N1*Ipp. The second temperature-controlled transistor group 22 compensates for the negative-inverting input terminal Vin- of the operational amplifier. The second temperature-controlled transistor group 22 conducts N2 branches based on transistors, and the compensation current for the negative-inverting input terminal Vin- of the operational amplifier is N2*Ipp. By reasonably setting the parameters of N1 and N2, the difference in current compensation between the non-inverting input terminal Vin+ and the negative input terminal Vin- of the operational amplifier is adjusted, thereby offsetting the mismatch between the non-inverting input terminal Vin+ and the negative input terminal Vin- of the operational amplifier.

[0033] Referring to Figure 4, which is a schematic diagram of a structure for generating compensation current, the compensation current Ipp mostly comes from the reference voltage Vref and the constant current generated by the poly resistor R3. This setup can indeed control the offset to a very small value at room temperature. However, since the op-amp offset itself changes with external environmental factors, while the compensation current changes relatively little with temperature, the compensated op-amp offset will still change significantly with temperature variations, thus amplifying the op-amp offset value.

[0034] One embodiment of this disclosure provides an operational amplifier structure in which the magnitude of the compensation current varies with temperature to improve the compensation effect of the compensation current on operational amplifier misalignment.

[0035] It will be understood by those skilled in the art that many technical details have been provided in the various embodiments of this disclosure to facilitate a better understanding of the disclosure. However, the technical solutions claimed in this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of this disclosure. The various embodiments can be combined with and referenced by each other without contradiction.

[0036] The operational amplifier structure provided in this embodiment will be described in detail below with reference to the accompanying drawings:

[0037] As mentioned above, after operational amplifier offset is compensated at room temperature, the offset changes with temperature. Research into the mechanism of operational amplifier offset reveals that it is mainly caused by mismatch in the transistor saturation region. Assuming the mismatch in the transistor saturation region is ΔVth, the relationship between the mismatch and the compensation current is Ipp = gm * ΔVth, where gm is the transconductance of the transistor. Based on the physical characteristics of gm in the saturation region, the compensation current required to compensate for the mismatch in the transistor saturation region is negatively correlated with temperature.

[0038] Based on this principle, referring to Figure 5, which is a schematic diagram of an operational amplifier structure provided in an embodiment of this disclosure, the operational amplifier structure provided in this embodiment includes: an operational amplifier 101 and a compensation module 102, wherein the compensation module 102 includes a compensation circuit 201 and a compensation current source 202, wherein the compensation circuit 201 is coupled to the operational amplifier 101, and the compensation circuit 201 is configured to generate a compensation current pair based on an initial compensation current Ios, the compensation current pair being used to reduce the operational amplifier mismatch of the operational amplifier 101; the compensation current source 202 is coupled to the compensation circuit 201 to provide the initial compensation current Ios; wherein the initial compensation current Ios is synthesized from a constant current and a temperature-controlled current Ictat, and the magnitude of the temperature-controlled current Ictat is negatively correlated with the temperature, wherein the value of the constant current is the same as the value of the compensation current Ipp mentioned above, and Ipp will be used to characterize the constant current thereafter.

[0039] By applying an initial compensation current that is negatively correlated with temperature to the compensation module 102, the magnitude of the compensation current for operational amplifier offset in the compensation module 102 is negatively correlated with temperature. When the external temperature changes, the compensation current for completing the mismatch compensation in the transistor saturation region changes in the same direction as the compensation current provided by the compensation module 102, so that the operational amplifier offset can still be well compensated after the temperature changes, even after it has been compensated at room temperature.

[0040] Specifically, the "same-direction change" mentioned above means that when the temperature rises, the compensation current required to complete the mismatch compensation of the transistor saturation region and the compensation current provided by the compensation module 102 decrease simultaneously; when the temperature falls, the compensation current required to complete the mismatch compensation of the transistor saturation region and the compensation current provided by the compensation module 102 increase simultaneously.

[0041] In some embodiments, referring to FIG6, FIG6 is a schematic diagram of the structure of a compensation current source provided in an embodiment of the present disclosure. For the compensation current source 202 shown in FIG5, the compensation current source 202 includes: a first operational amplifier 301, a second operational amplifier 302, a first resistor R04, a second resistor R05, a first transistor and a second transistor.

[0042] In this configuration, the non-inverting input terminal Vin+ of the first operational amplifier 301 receives a reference voltage Vref, and its output terminal Vout is connected to the gate of the first transistor. The source of the first transistor is connected to the first terminal of the first resistor R04 and to the negative input terminal Vin- of the first operational amplifier 301, while the second terminal of the first resistor R04 is grounded. The non-inverting input terminal Vin+ of the second operational amplifier 302 receives a temperature-controlled voltage Vbe, and its output terminal Vout is connected to the gate of the second transistor. The source of the second transistor is connected to the first terminal of the second resistor R05 and to the negative input terminal Vin- of the second operational amplifier 302, while the second terminal of the second resistor R05 is grounded. The drain of the first transistor generates a constant current Ipp, and the drain of the second transistor M2 generates a temperature-controlled current Ictat. The drains of the first and second transistors are connected to generate an initial compensation current Ios.

[0043] Specifically, the first operational amplifier 301 generates a constant current Ipp based on the reference voltage Vref, and the second operational amplifier 302 generates a temperature-controlled current Ictat based on the temperature-controlled voltage Vbe. The magnitude of the temperature-controlled voltage Vbe is negatively correlated with the temperature, so that the magnitude of the temperature-controlled current Ictat generated by the second operational amplifier 302 is negatively correlated with the temperature. After connecting the drains of the first transistor and the drains of the second transistor, the initial compensation current Ios = Ipp + Ictat is made up of the constant current Ipp and the temperature-controlled current Ictat. At this time, the magnitude of the compensation current Ios is negatively correlated with the temperature.

[0044] It should be noted that the terms "source" and "drain" mentioned in the above description are only used to illustrate the connection relationship of the terminals of the first and second transistors when the first and second transistors are NMOS. In specific applications, if the first and second transistors are PMOS, the positions of the "source" and "drain" mentioned above can be replaced accordingly.

[0045] In some embodiments, the first resistor R04 and the second resistor R05 are configured as resistors with adjustable resistance values, such as sliding resistors, resistance boxes, etc. Specifically, the constant current Ipp = Vref / R04, the temperature-controlled current Ictat = Vbe / R05, that is, the initial compensation current Ios = Vref / R04 + Vbe / R05. In other words, by adjusting the resistance values ​​of the first resistor and the second resistor, the proportion of the constant current Ipp and the temperature-controlled current Ictat in the initial compensation current Ios can be changed, thereby adjusting the magnitude of the change in the initial compensation current Ios with temperature.

[0046] In some embodiments, the compensation current source 202 further includes a voltage generation circuit coupled to a second operational amplifier 302. The voltage generation circuit is configured to generate a temperature-controlled voltage Vbe based on the temperature of the operational amplifier structure, wherein the magnitude of the temperature-controlled voltage Vbe is negatively correlated with the temperature of the operational amplifier structure.

[0047] In a specific example, referring to Figure 7, which is a schematic diagram of a voltage generation circuit provided in an embodiment of the present disclosure, the voltage generation circuit includes: a temperature-controlled current source 401, the input terminal of which is used to receive the power supply voltage and the output terminal of which is used to output the temperature-controlled voltage Vbe; and a temperature-controlled transistor 402, the emitter of which is connected to the output terminal of the temperature-controlled current source 401, the base of which is connected to the collector and the collector is grounded.

[0048] In a specific example, referring to Figure 8, which is a schematic diagram of another voltage generation circuit provided in an embodiment of the present disclosure, the voltage generation circuit includes: a temperature-controlled current source 501, the input terminal of which is used to receive the power supply voltage and the output terminal of which is used to output the temperature-controlled voltage Vbe; a temperature-controlled MOSFET 502, the gate of which is connected to the drain and the drain of which is connected to the output terminal of the temperature-controlled current source 501, and the source of which is grounded, wherein the temperature-controlled MOSFET 502 is configured to operate in the subthreshold region.

[0049] It should be noted that this embodiment does not constitute a limitation on the specific types of temperature-controlled transistor 402 and temperature-controlled MOSFET 502 as illustrated in Figure 7 and Figure 8, respectively. In specific applications, the connection method of the corresponding terminals can be selected based on the type of temperature-controlled transistor 402 and temperature-controlled MOSFET 502.

[0050] Referring to Figure 9, which is a schematic diagram of the operational amplifier and compensation circuit in an operational amplifier structure provided in an embodiment of this disclosure, the compensation circuit 201 in the operational amplifier structure includes: a main control transistor P1, whose source receives the power supply voltage and whose drain is connected to the gate, and whose drain is used to receive the initial compensation current Ios; a first temperature-controlled transistor group 21, including a plurality of first temperature-controlled transistors, wherein the source of each first temperature-controlled transistor is connected to the source of the main control transistor P1 and its gate is connected to the gate of the main control transistor P1, and the drains of the plurality of first temperature-controlled transistors are interconnected to generate a first compensation current; a second temperature-controlled transistor group 22, including a plurality of second temperature-controlled transistors, wherein the source of each second temperature-controlled transistor is connected to the source of the main control transistor P1 and its gate is connected to the gate of the main control transistor P1, and the drains of the plurality of second temperature-controlled transistors are interconnected to generate a second compensation current; wherein the first compensation current and the second compensation current constitute a compensation current pair.

[0051] Specifically, if N1 first temperature control transistors are turned on in the first temperature control transistor group 21, the value of the first compensation current generated is N1*Ios; if N2 second temperature control transistors are turned on in the second temperature control transistor group 22, the value of the second compensation current generated is N2*Ios.

[0052] It should be noted that in specific applications, N1 and N2 can be configured to have the same value or different values ​​(including N1 > N2 and N2 > N1); specifically, the values ​​of N1 and N2 are determined based on the magnitude of the compensation current required by the operational amplifier.

[0053] Referring again to Figure 9, for the operational amplifier structure provided in this embodiment, the operational amplifier 101 includes a first-stage amplifier circuit 601 and a second-stage amplifier circuit 602. The first-stage amplifier circuit 601 is configured to amplify the input signals at the non-inverting input terminal Vin+ and the negative-inverting input terminal Vin- of the operational amplifier 101 to generate an initial output signal. The second-stage amplifier circuit 602 is connected to the first-stage amplifier circuit 601 and is configured to amplify the initial output signal to generate an output signal. The first compensation current and the second compensation current mentioned above constitute a compensation current pair used to compensate for the magnitude of the initial output signal.

[0054] In one example, the first-stage amplifier circuit 601 includes: a first switching transistor P07, whose source is used to receive the power supply voltage and whose gate is used to receive the first switching signal Vp1; a first P-type transistor P01, whose source is connected to the drain of the first switching transistor P07 and whose gate serves as the non-inverting input terminal Vin+ of the operational amplifier 101; a second P-type transistor P02, whose source is connected to the drain of the first switching transistor P07 and whose gate serves as the non-inverting input terminal Vin- of the operational amplifier; the drains of the first P-type transistor P01 and the drains of the second P-type transistor P02 are used to output the initial output signal.

[0055] In one example, the second-stage amplifier circuit 602 includes: a third P-type transistor P03, the source of which receives the power supply voltage; a fourth P-type transistor P04, the source of which receives the power supply voltage, and its gate connected to the gate of the third P-type transistor P03; a fifth P-type transistor P05, the source of which is connected to the drain of the third P-type transistor P03, and the drain of which is connected to the gate of the third P-type transistor P03, the gate of which receives the fourth switching signal Vp2; a sixth P-type transistor P06, the source of which is connected to the drain of the fourth P-type transistor P04, and the gate of which is connected to the gate of the fifth P-type transistor P05, the drain of which serves as the output terminal Vout of the operational amplifier 101; and a first N-type transistor N01, the drain of which is connected to the fourth P-type transistor P04. The drain and source of the fifth P-type transistor P05 are connected to the drain of the first P-type transistor P01 and receive a compensation current pair, and the gate is used to receive the second switching signal Vn2; the drain of the second N-type transistor N02 is connected to the drain of the sixth P-type transistor P06, the source is connected to the drain of the second P-type transistor P02 and receive a compensation current pair, and the gate is connected to the gate of the first N-type transistor N01; the drain of the third N-type transistor N03 is connected to the source of the first N-type transistor N01, the source is grounded, and the gate is used to receive the third switching signal Vn1; the drain of the fourth N-type transistor N04 is connected to the source of the second N-type transistor N02, the source is grounded, and the gate is connected to the gate of the third N-type transistor N03.

[0056] In some embodiments, the fifth P-type transistor P05, the sixth P-type transistor P06, the first N-type transistor N01, and the second N-type transistor N02 may be omitted from the second-stage amplifier circuit 602 to form a simpler second-stage amplifier circuit.

[0057] It should be noted that the first switch signal Vp1 and the fourth switch signal Vp2 are two signals of the same level or constitute the same signal; the second switch signal Vn2 and the third switch signal Vn1 are two signals of the same level or constitute the same signal; the first switch signal Vp1 and the second switch signal Vn2 are two signals of opposite levels or constitute the same signal in reverse phase.

[0058] It should also be noted that the terms "source" and "drain" mentioned in the above description are only used as illustrative examples of the transistor type shown in Figure 9; in specific applications, if the type of the corresponding transistor changes, the positions of the "source" and "drain" mentioned above can be replaced accordingly.

[0059] As discussed above, assuming the op-amp structure has an equivalent input offset of Vos, for a well-designed op-amp structure, the equivalent input offset mainly originates from the mismatch of the threshold voltage Vth of the first P-type transistor P01 and the second P-type transistor P02. By initially compensating the drain current Ios of the first P-type transistor P01 and the drain of the second P-type transistor P02, this equivalent input offset Vos can be compensated.

[0060] Wherein, N*Ios=Vos*gm; gm is the transconductance of the first P-type transistor P01 and the second P-type transistor P02, and N is the encoded value of the first temperature control transistor group 21 and the second temperature control transistor group 22, so as to adjust the magnitude of the compensation current based on the initial compensation current Ios.

[0061] Transistor mobility exhibits a negative correlation with temperature. Based on the relationship between gm and mobility, gm also shows a strong negative temperature correlation. Assuming the temperature coefficient is... ɑ As shown in Figure 6, the initial compensation current Ios provided in this disclosure includes a constant current Ipp and a temperature-controlled current Ictat, where Ictat = Vbe / R05. Based on Figures 7 and 8, the temperature-controlled voltage Vbe is generated based on the base and emitter voltages of the transistor, or based on the drain-source voltage Vgs of the MOSFET operating in the subthreshold region. This results in a strong negative temperature correlation for the temperature-controlled voltage Vbe, greater than that of gm. Assuming the temperature coefficient is β, β is greater than... ɑ .

[0062] After considering the temperature parameter, Vos*gm=Vos0*gm0*(1+*T), where Vos0 is Vos at absolute 0 degrees and gm0 is gm at absolute 0 degrees; Ios=Ipp+Ictat=K1*Ipp+K2*Ictat0*(1+βT), where Ictat0 is Ictat at absolute 0 degrees, K1 is the resistance adjustment ratio of the first resistor R04, and K2 is the resistance adjustment ratio of the second resistor R05.

[0063] Combining the above formulas, we can obtain: Vos0·gm0=N·(K1·Ipp+K2·Ictat0) (3);

[0064] When equations (2) and (3) are satisfied, equation (1) holds, that is, the equivalent input offset of the op-amp structure with Vos is completely eliminated. For equation (2), the temperature coefficient... ɑWith β, Ipp and Ictat0 as known values, the setting parameters of the first resistor R04 and the second resistor R05 can be obtained by formula (2). Then, K1 and K2 can be substituted into formula (3) to obtain the encoding values ​​of the first temperature control transistor group 21 and the second temperature control transistor group 22.

[0065] It should be noted that in some embodiments, the constant current Ipp can also be set as a temperature-controlled current that is positively correlated with temperature; in some embodiments, if the encoding values ​​of the first temperature-controlled transistor group 21 and the second temperature-controlled transistor group 22 are fixed, the values ​​of K1 and K2 can also be determined based on formulas (2) and (3) to completely eliminate the equivalent input offset of the operational amplifier structure with Vos by using only K1 and K2 as adjustment terms; in some embodiments, K1 and K2 can also be adjusted based on the setting method of the current mirror.

[0066] In summary, by applying an initial compensation current that is negatively correlated with temperature to the compensation module 102, the magnitude of the compensation current for operational amplifier offset in the compensation module 102 is negatively correlated with temperature. When the external temperature changes, the compensation current for completing the mismatch compensation in the transistor saturation region changes in the same direction as the compensation current provided by the compensation module 102, so that the operational amplifier offset can still be well compensated after the temperature changes, even after it has been compensated at room temperature.

[0067] The operational amplifier structure provided in this disclosure can reduce operational amplifier offset by a small value across the entire temperature range. Specifically, it compensates for mismatches caused by process variations as well as those caused by temperature changes, thereby achieving high-precision output from the operational amplifier structure.

[0068] It should be noted that the features disclosed in the operational amplifier structure provided in the above embodiments can be arbitrarily combined without conflict to obtain new operational amplifier structure embodiments.

[0069] Another embodiment of this disclosure is used to provide an integrated circuit, in which the operational amplifier structure provided in the above embodiments is disposed.

[0070] Referring to Figure 5, the operational amplifier structure includes an operational amplifier 101 and a compensation module 102. The compensation module 102 includes a compensation circuit 201 and a compensation current source 202. The compensation circuit 201 is coupled to the operational amplifier 101 and is configured to generate a compensation current pair based on an initial compensation current Ios. The compensation current pair is used to reduce the operational amplifier mismatch of the operational amplifier 101. The compensation current source 202 is coupled to the compensation circuit 201 to provide the initial compensation current Ios. The initial compensation current Ios is synthesized from a constant current Ipp and a temperature-controlled current Ictat, and the magnitude of the temperature-controlled current Ictat is negatively correlated with the temperature.

[0071] It should be noted that the integrated circuit provided in this embodiment can be used in various types of electronic products, such as mobile phones, tablets, computers, and artificial intelligence hardware devices. Any integrated circuit in the hardware structure of a practical device that includes the operational amplifier structure provided in the above embodiment should fall within the protection scope of this application.

[0072] It is not difficult to see that this embodiment can be implemented in conjunction with the operational amplifier structure provided in the previous embodiment. The relevant technical details mentioned in the previous embodiment are still valid in this embodiment, and will not be repeated here to avoid repetition.

[0073] Those skilled in the art will understand that the above embodiments are specific implementations of this application, and in practical applications, various changes can be made in form and detail without departing from the spirit and scope of this application.

Claims

1. An operational amplifier structure, comprising an operational amplifier (101) and a compensation module (102), wherein the compensation module (102) comprises: A compensation circuit (201), coupled to the operational amplifier (101), is configured to generate a compensation current pair based on an initial compensation current (Ios), the compensation current pair being used to reduce op-amp mismatch in the operational amplifier (101). A compensation current source (202) is coupled to the compensation circuit (201) to provide the initial compensation current (Ios); wherein the initial compensation current (Ios) is synthesized from a constant current and a temperature-controlled current (Ictat), and the magnitude of the temperature-controlled current (Ictat) is negatively correlated with the temperature.

2. The operational amplifier structure according to claim 1, wherein, The compensation current source (202) includes: The first operational amplifier (301) has a non-inverting input terminal (Vin+) for receiving a reference voltage (Vref), and its output terminal is connected to the gate of the first transistor. The source of the first transistor is connected to the first terminal of the first resistor (R04) and to the negative input terminal of the first operational amplifier (301), and the second terminal of the first resistor (R04) is grounded. The second operational amplifier (302) has a non-inverting input terminal (Vin+) for receiving the temperature control voltage (Vbe), and its output terminal is connected to the gate of the second transistor. The source of the second transistor is connected to the first terminal of the second resistor (R05) and to the negative input terminal of the second operational amplifier (302), and the second terminal of the second resistor (R05) is grounded; The drain of the first transistor is used to generate the constant current (Ipp), the drain of the second transistor is used to generate the temperature-controlled current (Ictat), and the drains of the first transistor and the second transistor are connected to synthesize and generate the initial compensation current (Ios).

3. The operational amplifier structure according to claim 2, wherein, The first resistor (R04) and the second resistor (R05) are configured as resistors with adjustable resistance values.

4. The operational amplifier structure according to claim 2, wherein, The compensation current source (202) further includes a voltage generation circuit coupled to the second operational amplifier (302), configured to generate the temperature control voltage (Vbe) based on the temperature of the operational amplifier structure, wherein the magnitude of the temperature control voltage (Vbe) is negatively correlated with the temperature of the operational amplifier structure.

5. The operational amplifier structure according to claim 4, wherein, The voltage generating circuit includes: The temperature-controlled current source (401) has an input terminal for receiving power supply voltage and an output terminal for outputting the temperature-controlled voltage (Vbe). The temperature-controlled transistor (402) has its emitter connected to the output terminal of the temperature-controlled current source (401), and its base connected to the collector, which is grounded.

6. The operational amplifier structure according to claim 4, wherein, The voltage generating circuit includes: The temperature-controlled current source (501) has an input terminal for receiving power supply voltage and an output terminal for outputting the temperature-controlled voltage (Vbe). The temperature-controlled MOSFET (502) has its gate connected to its drain and its drain connected to the output terminal of the temperature-controlled current source (501), and its source grounded. The temperature-controlled MOS transistor (502) is configured to operate in the subthreshold region.

7. The operational amplifier structure according to any one of claims 1 to 6, wherein, The compensation circuit (201) includes: The main control transistor (P1) has a source that receives the power supply voltage, a gate connected to the drain, and the drain is used to receive the initial compensation current (Ios). The first temperature-controlled transistor group (21) includes a plurality of first temperature-controlled transistors, wherein the source of each first temperature-controlled transistor is connected to the source of the main control transistor (P1), and the gate is connected to the gate of the main control transistor (P1). The drains of the plurality of first temperature-controlled transistors are connected to each other to generate a first compensation current. The second temperature control transistor group (22) includes a plurality of second temperature control transistors, wherein the source of each second temperature control transistor is connected to the source of the main control transistor (P1), and the gate is connected to the gate of the main control transistor (P1). The drains of the plurality of second temperature control transistors are connected to each other to generate a second compensation current. The first compensation current and the second compensation current constitute the compensation current pair.

8. The operational amplifier structure according to any one of claims 1 to 6, wherein, The operational amplifier (101) includes: The first-stage amplifier circuit (601) is configured to amplify the input signals at the non-inverting input terminal (Vin+) and the negative-inverting input terminal (Vin-) of the operational amplifier to generate an initial output signal; The second-stage amplifier circuit (602), connected to the first-stage amplifier circuit (601), is configured to amplify the initial output signal to generate an output signal; The compensation current is used to compensate for the magnitude of the initial output signal.

9. The operational amplifier structure according to claim 8, wherein, include: The first stage amplifier circuit (601) includes: The first switching transistor (P07) has its source used to receive the power supply voltage and its gate used to receive the first switching signal (Vp1). The first P-type transistor (P01) has its source connected to the drain of the first switching transistor (P07), and its gate is used as... The non-inverting input terminal of the operational amplifier (101); The source of the second P-type transistor (P02) is connected to the drain of the first switch transistor (P07), and the gate is used as the negative input terminal of the operational amplifier (101). The drain of the first P-type transistor (PO1) and the drain of the second P-type transistor (PO2) are used to output the initial output signal; The second-stage amplifier circuit (602) includes: The third P-type transistor (P03) has its source used to receive the power supply voltage; The fourth P-type transistor (PO4) has its source used to receive the power supply voltage and its gate connected to the gate of the third P-type transistor (PO3). The fifth P-type transistor (PO5) has its source connected to the drain of the third P-type transistor (PO3), and its drain connected to the gate of the third P-type transistor (PO3). The sixth P-type transistor (P06) has its source connected to the drain of the fourth P-type transistor (P04), its gate connected to the gate of the fifth P-type transistor (P05), and its drain serves as the output terminal (Vout) of the operational amplifier (101). The first N-type transistor (N01) has its drain connected to the drain of the fifth P-type transistor (P05), its source connected to the drain of the first P-type transistor (P01) and receiving the compensation current pair, and its gate used to receive the second switching signal (Vn2). The second N-type transistor (NO2) has its drain connected to the drain of the sixth P-type transistor (PO6), its source connected to the drain of the second P-type transistor (PO2) and receiving the compensation current pair, and its gate connected to the gate of the first N-type transistor (NO1). The third N-type transistor (N03) has its drain connected to the source of the first N-type transistor (N01), its source grounded, and its gate used to receive the third switching signal (Vn1). The fourth N-type transistor (NO4) has its drain connected to the source of the second N-type transistor (NO2), the source is grounded, and its gate is connected to the gate of the third N-type transistor (NO3).

10. An integrated circuit, wherein the integrated circuit is provided with an operational amplifier structure as described in any one of claims 1 to 9.

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