CN118100816A - Operational amplifier structure and integrated circuit - Google Patents
Operational amplifier structure and integrated circuit Download PDFInfo
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- CN118100816A CN118100816A CN202410482744.5A CN202410482744A CN118100816A CN 118100816 A CN118100816 A CN 118100816A CN 202410482744 A CN202410482744 A CN 202410482744A CN 118100816 A CN118100816 A CN 118100816A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
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- G05F3/02—Regulating voltage or current
- G05F3/08—Regulating voltage or current wherein the variable is dc
- G05F3/10—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics
- G05F3/16—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices
- G05F3/20—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices using diode- transistor combinations
- G05F3/26—Current mirrors
- G05F3/262—Current mirrors using field-effect transistors only
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
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Abstract
The present disclosure relates to the field of semiconductor device design, and in particular, to an operational amplifier structure and an integrated circuit, where the operational amplifier structure includes an operational amplifier and a compensation module, where the compensation module includes: a compensation circuit coupled to the operational amplifier and configured to generate a compensation current pair based on the initial compensation current, the compensation current pair for reducing operational amplifier mismatch; a compensation current source coupled to the compensation circuit for providing an initial compensation current; the initial compensation current is synthesized by constant current and temperature control current, and the magnitude of the temperature control current is inversely related to the temperature; the compensation effect of the compensation current on the operational amplifier offset is improved by setting the compensation current to change along with the temperature change.
Description
Technical Field
The present disclosure relates to the field of semiconductor device design, and in particular, to an operational amplifier structure and an integrated circuit.
Background
Operational amplifier offset, generally referred to as non-zero voltage offset generated at the output of an operational amplifier (hereinafter referred to as operational amplifier) under normal operating conditions. The non-zero voltage offset is mainly due to parameter mismatch of internal components of the op-amp, influence of external environmental factors (such as temperature, humidity, pressure, etc.) of the op-amp, and process limitation of the op-amp in the manufacturing process.
For example, for the voltage source structure shown in fig. 1, the output voltage vout= (vref+Δvos) ×1+r0)/R0, and for the current source structure shown in fig. 2, the output current iout= (vref+Δvos)/R2, where Δvos is the equivalent input offset voltage of the op-amp; therefore, the operational amplifier offset has serious influence on the output results of the current source and the voltage source, and the reduction of the operational amplifier offset is very critical in circuits with high performance requirements such as the voltage source and the current source.
Disclosure of Invention
The embodiment of the disclosure provides an operational amplifier structure and an integrated circuit, which are used for improving the offset compensation effect of compensation current on operational amplifier offset by setting the change of the compensation current along with the temperature change.
An embodiment of the present disclosure provides an operational amplifier structure, including an operational amplifier and a compensation module, wherein the compensation module includes: a compensation circuit coupled to the operational amplifier and configured to generate a compensation current pair based on the initial compensation current, the compensation current pair for reducing operational amplifier mismatch; a compensation current source coupled to the compensation circuit for providing an initial compensation current; the initial compensation current is synthesized by constant current and temperature control current, and the magnitude of the temperature control current is inversely related to the temperature.
The initial compensation current of the negative temperature correlation is applied to the compensation module, so that the compensation module carries out the offset compensation current of the operational amplifier and the magnitude of the offset compensation current are in the negative temperature correlation; when the external temperature changes, the compensation current for completing the mismatch compensation of the transistor saturation region and the compensation current provided by the compensation module are changed in the same direction, so that the operational amplifier offset can be better compensated after being compensated at normal temperature and along with the temperature change.
In some embodiments, the compensation current source comprises: the non-inverting input end of the first operational amplifier is used for receiving the reference voltage, and the output end of the first operational amplifier is connected with the grid electrode of the first transistor; the source electrode of the first transistor is connected with the first end of the first resistor, and is connected with the negative phase input end of the first operational amplifier, and the second end of the first resistor is grounded; the non-inverting input end of the second operational amplifier is used for receiving the temperature control voltage, and the output end of the second operational amplifier is connected with the grid electrode of the second transistor; the source electrode of the second transistor is connected with the first end of the second resistor and is connected with the negative phase input end of the second operational amplifier, and the second end of the second resistor is grounded; the drain electrode of the first transistor is used for generating constant current, the drain electrode of the second transistor is used for generating temperature control current, and the drain electrode of the first transistor is connected with the drain electrode of the second transistor so as to synthesize and generate initial compensation current.
In some embodiments, the first resistor and the second resistor are configured as resistors with adjustable resistance values.
In some embodiments, the compensation current source further comprises: the voltage generating circuit is coupled to the second operational amplifier and configured to generate a temperature control voltage based on the temperature of the operational amplifier structure, wherein the magnitude of the temperature control voltage is inversely related to the temperature of the operational amplifier structure.
In some embodiments, the voltage generation circuit includes: the temperature control current source is used for receiving the power supply voltage at the input end and outputting the temperature control voltage at the output end; and the emitting electrode of the temperature control triode is connected with the output end of the temperature control current source, the base electrode of the temperature control triode is connected with the collecting electrode, and the collecting electrode is grounded.
In some embodiments, the voltage generation circuit includes: the temperature control current source is used for receiving the power supply voltage at the input end and outputting the temperature control voltage at the output end; the grid electrode of the temperature control MOS tube is connected with the drain electrode, the drain electrode is connected with the output end of the temperature control current source, and the source electrode is grounded; the temperature control MOS tube is configured to work in a subthreshold region.
In some embodiments, the compensation circuit includes: the source electrode of the main control transistor receives the power supply voltage, the grid electrode of the main control transistor is connected with the drain electrode, and the drain electrode is used for receiving initial compensation current; the first temperature control transistor group comprises a plurality of first temperature control transistors, wherein the source electrode of each first temperature control transistor is connected with the source electrode of the main control transistor, the grid electrode is connected with the grid electrode of the main control transistor, and the drain electrodes of the plurality of first temperature control transistors are connected with each other to generate a first compensation current; the second temperature control transistor group comprises a plurality of second temperature control transistors, wherein the source electrode of each second temperature control transistor is connected with the source electrode of the main control transistor, the grid electrode is connected with the grid electrode of the main control transistor, and the drain electrodes of the plurality of second temperature control transistors are connected with each other to generate a second compensation current; wherein the first compensation current and the second compensation current form a compensation current pair.
In some embodiments, an operational amplifier includes: a first stage amplifying circuit configured to amplify input signals of a positive phase input terminal and a negative phase input terminal of the operational amplifier to generate an initial output signal; a second stage amplifying circuit connected to the first stage amplifying circuit and configured to amplify the initial output signal to generate an output signal; wherein the compensation current pair is used to compensate for the magnitude of the initial output signal.
In some embodiments, the first stage amplification circuit comprises: the first switch tube comprises a source electrode for receiving a power supply voltage and a grid electrode for receiving a first switch signal; the source electrode of the first P-type transistor is connected with the drain electrode of the first switch tube, and the grid electrode of the first P-type transistor is used as the non-inverting input end of the operational amplifier; the source electrode of the second P-type transistor is connected with the drain electrode of the first switch tube, and the grid electrode of the second P-type transistor is used as the negative phase input end of the operational amplifier; the drain electrode of the first P-type transistor and the drain electrode of the second P-type transistor are used for outputting an initial output signal; the second-stage amplification circuit includes: the source electrode of the third P-type transistor is used for receiving a power supply voltage; the source electrode of the fourth P-type transistor is used for receiving power supply voltage, and the grid electrode of the fourth P-type transistor is connected with the grid electrode of the third P-type transistor; a fifth P-type transistor, wherein the source electrode is connected with the drain electrode of the third P-type transistor, and the drain electrode is connected with the grid electrode and the grid electrode of the third P-type transistor; a source electrode of the sixth P-type transistor is connected with a drain electrode of the fourth P-type transistor, a grid electrode of the sixth P-type transistor is connected with a grid electrode of the fifth P-type transistor, and the drain electrode is used as an output end of the operational amplifier; the drain electrode of the first N-type transistor is connected with the drain electrode of the fifth P-type transistor, the source electrode of the first N-type transistor is connected with the drain electrode of the first P-type transistor and receives the compensation current pair, and the grid electrode of the first N-type transistor is used for receiving the second switching signal; the drain electrode of the second N-type transistor is connected with the drain electrode of the sixth P-type transistor, the source electrode of the second N-type transistor is connected with the drain electrode of the second P-type transistor and receives the compensation current pair, and the grid electrode of the second N-type transistor is connected with the grid electrode of the first N-type transistor; the drain electrode of the third N-type transistor is connected with the source electrode of the first N-type transistor, the source electrode is grounded, and the grid electrode is used for receiving a third switching signal; and the drain electrode of the fourth N-type transistor is connected with the source electrode of the second N-type transistor, the source electrode is grounded, and the grid electrode of the fourth N-type transistor is connected with the grid electrode of the third N-type transistor.
Another embodiment of the present disclosure provides an integrated circuit, in which the operational amplifier structure provided in the foregoing embodiment is disposed.
Drawings
One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, which are not to be construed as limiting the embodiments unless specifically indicated otherwise; in order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the conventional technology, the drawings required for the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present disclosure, and other drawings may be obtained according to these drawings without inventive effort to those of ordinary skill in the art.
FIG. 1 is a schematic diagram of a voltage source;
FIG. 2 is a schematic diagram of a current source;
FIG. 3 is a schematic diagram of an operational amplifier;
FIG. 4 is a schematic diagram of a structure for generating compensation current;
Fig. 5 is a schematic structural diagram of an operational amplifier structure according to an embodiment of the disclosure;
FIG. 6 is a schematic diagram of a compensation current source according to an embodiment of the disclosure;
FIG. 7 is a schematic diagram of a voltage generation circuit according to an embodiment of the disclosure;
FIG. 8 is a schematic diagram of another voltage generation circuit according to an embodiment of the disclosure;
fig. 9 is a schematic diagram of an operational amplifier and a compensation circuit in an operational amplifier structure according to an embodiment of the disclosure.
Detailed Description
There are many ways to eliminate the effects of Δvos. For example, the size of the op-amp is made larger at the expense of area to reduce the effects of Δvos; there are also ways to cancel Δvos by supplying a compensation current, but since Δvos varies not only with a process but also with external environmental factors such as a power supply voltage, a temperature, etc., the effect of canceling Δvos by the compensation current is poor.
In a voltage source circuit or a current source circuit with very high precision requirements, the requirement on operational amplifier offset compensation is very strict, and besides the large-area operational amplifier is used for reducing the influence of the operational amplifier offset, the operational amplifier offset is further reduced by a current compensation method.
In an example, referring to fig. 3, fig. 3 is a schematic structural diagram of an operational amplifier, where the operational amplifier with offset compensation function includes: the operational amplifier 10 and the compensation module 11, the compensation module 11 compensates the mismatch between the input terminals vin+ and Vin-of the operational amplifier 10 based on the compensation current Ipp and the number of on compensation branches.
Specifically, the first temperature-controlled transistor group 21 compensates the positive input terminal vin+ of the operational amplifier, and the first temperature-controlled transistor group 21 conducts N1 branches based on the transistors, and compensates the positive input terminal vin+ of the operational amplifier by N1×ipp; the second temperature control transistor group 22 compensates the negative phase input end Vin-of the operational amplifier, and the second temperature control transistor group 22 conducts N2 branches based on the transistors, so that the compensation current of the negative phase input end Vin-of the operational amplifier is N2 x Ipp; the parameters of N1 and N2 are reasonably set to adjust the difference value of current compensation between the positive phase input end Vin+ and the negative phase input end Vin-of the operational amplifier, so that mismatch between the positive phase input end Vin+ and the negative phase input end Vin-of the operational amplifier is counteracted.
Referring to fig. 4, fig. 4 is a schematic diagram of a structure for generating a compensation current Ipp mostly from a constant current generated by a reference voltage Vref and a poly resistor R3. The offset can be controlled to be very small at normal temperature, but the offset of the operational amplifier can change along with external environmental factors, and the compensation current changes little along with temperature, so that the offset of the operational amplifier after compensation can change greatly under the temperature change, and the offset of the operational amplifier is amplified.
An embodiment of the present disclosure provides an operational amplifier structure, which improves the compensation effect of compensation current on operational amplifier offset by setting the magnitude of compensation current to change with temperature change.
Those of ordinary skill in the art will understand that in various embodiments of the present disclosure, numerous technical details are set forth in order to provide a better understanding of the present disclosure. The technical solutions claimed in the present disclosure can be implemented without these technical details and with various changes and modifications based on the following embodiments. The following embodiments are divided for convenience of description, and should not be construed as limiting the specific implementation of the disclosure, and the embodiments can be combined with each other and cited with each other without contradiction.
The following describes the operational amplifier structure provided in this embodiment in detail with reference to the accompanying drawings, and specifically includes:
Based on the foregoing, after the operational amplifier imbalance is compensated at normal temperature, the operational amplifier imbalance has a problem of changing with temperature change. Through research on an operational amplifier offset generating mechanism, the operational amplifier offset is mainly caused by mismatch of a transistor saturation region, and the mismatch of the transistor saturation region is assumed to be delta Vth, the relation between the mismatch of the transistor saturation region and the compensation current is ipp=gm, wherein gm is transconductance of the transistor, and according to physical characteristics of gm in the saturation region, the compensation current for completing mismatch compensation of the transistor saturation region is inversely related to temperature.
Based on this principle, referring to fig. 5, fig. 5 is a schematic structural diagram of an operational amplifier structure provided in an embodiment of the present disclosure, where the operational amplifier structure provided in the embodiment includes: the operational amplifier 101 and the compensation module 102, wherein the compensation module 102 comprises a compensation circuit 201 and a compensation current source 202, wherein the compensation circuit 201 is coupled to the operational amplifier 101, the compensation circuit 201 is configured to generate a compensation current pair based on the initial compensation current Ios, the compensation current pair being used to reduce operational amplifier mismatch of the operational amplifier 101; the compensation current source 202 is coupled to the compensation circuit 201 to provide an initial compensation current Ios; the initial compensation current Ios is synthesized by a constant current and a temperature control current Ictat, and the magnitude of the temperature control current Ictat is inversely related to the temperature, wherein the value of the constant current is the same as the value of the compensation current Ipp described above, and the constant current is subsequently characterized by the Ipp.
The initial compensation current of the negative temperature correlation is applied to the compensation module 102, so that the magnitude of the compensation current of the operational amplifier imbalance carried out by the compensation module 102 is in the negative temperature correlation; when the external temperature changes, the compensation current for completing the mismatch compensation of the transistor saturation region and the compensation current provided by the compensation module 102 are changed in the same direction, so that the operational amplifier offset can be better compensated after being compensated at normal temperature and along with the temperature change.
Specifically, for the above-mentioned "homodromous change", it means that when the temperature increases, the compensation current required for completing the mismatch compensation of the saturation region of the transistor decreases simultaneously with the compensation current provided by the compensation module 102; when the temperature decreases, the compensation current required to complete the mismatch compensation in the saturation region of the transistor increases simultaneously with the compensation current provided by the compensation module 102.
In some embodiments, referring to fig. 6, fig. 6 is a schematic structural diagram of a compensation current source provided in an embodiment of the disclosure, for the compensation current source 202 shown in fig. 5, 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.
The non-inverting input terminal vin+ of the first operational amplifier 301 is configured to receive a reference voltage Vref, and the output terminal Vout is connected to the gate of the first transistor; the source electrode of the first transistor is connected with the first end of the first resistor R04 and is connected with the negative phase input end Vin-of the first operational amplifier 301, and the second end of the first resistor R04 is grounded; the non-inverting input terminal vin+ of the second operational amplifier 302 is used for receiving the temperature control voltage Vbe, and the output terminal Vout is connected to the gate of the second transistor; the source of the second transistor is connected to the first end of the second resistor R05, and is connected to the negative input terminal Vin-of the second operational amplifier 302, and the second end of the second resistor R05 is grounded. The drain of the first transistor is used for generating a constant current Ipp, the drain of the second transistor M2 is used for generating a temperature control current Ictat, and the drain of the first transistor is connected with the drain of the second transistor to generate an initial compensation current Ios.
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, wherein the magnitude of the temperature-controlled voltage Vbe is inversely related to temperature, so that the magnitude of the temperature-controlled current Ictat generated by the second operational amplifier 302 is inversely related to temperature; after the drain electrode of the first transistor and the drain electrode of the second transistor are connected, the initial compensation current ios=ipp+ictat, that is, the initial compensation current Ios is synthesized by the constant current Ipp and the temperature control current Ictat, and at this time, the magnitude of the compensation current Ios is inversely related to the temperature.
It should be noted that, the "source" and the "drain" mentioned in the above description are only used to exemplify the connection relationship of the respective terminals of the first transistor and the second transistor when the first transistor and the second transistor are NMOS; in a specific application, if the first transistor and the second transistor are PMOS, the positions of the "source" and the "drain" mentioned above may be replaced accordingly.
In some embodiments, the first resistor R04 and the second resistor R05 are configured as resistors with adjustable resistance values, such as sliding resistors, resistor boxes, and the like. Specifically, the constant current ipp=vref/R04, the temperature control current ictat=vbe/R05, that is, the initial compensation current ios=vref/r04+vbe/R05, the duty ratio of the constant current Ipp and the temperature control current Ictat in the initial compensation current Ios can be changed by adjusting the resistance values of the first resistor and the second resistor, and the amplitude of the initial compensation current Ios varying with the temperature can be adjusted.
In some embodiments, the compensation current source 202 further comprises a voltage generating circuit coupled to the second operational amplifier 302, the voltage generating circuit 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 inversely related to the temperature of the operational amplifier structure.
In a specific example, referring to fig. 7, fig. 7 is a schematic structural diagram of a voltage generating circuit according to an embodiment of the present disclosure, where the voltage generating circuit includes: the temperature-controlled current source 401 has an input end for receiving a power supply voltage and an output end for outputting a temperature-controlled voltage Vbe; and the emitter of the temperature control triode 402 is connected with the output end of the temperature control current source 401, the base of the temperature control triode is connected with the collector of the temperature control current source and the collector of the temperature control triode is grounded.
In a specific example, referring to fig. 8, fig. 8 is a schematic structural diagram of another voltage generating circuit according to an embodiment of the present disclosure, the voltage generating circuit includes: the temperature control current source 501 has an input end for receiving a power supply voltage and an output end for outputting a temperature control voltage Vbe; the gate of the temperature-controlled MOS transistor 502 is connected to the drain and the drain is connected to the output end of the temperature-controlled current source 401, and the source is grounded, wherein the temperature-controlled MOS transistor 502 is configured to operate in the subthreshold region.
It should be noted that, for the temperature-controlled transistor 402 illustrated in fig. 7 and the temperature-controlled MOS transistor 502 illustrated in fig. 8, the specific types of the temperature-controlled transistor 402 and the temperature-controlled MOS transistor 502 are not limited in this embodiment; the manner of connection of the respective terminals may be selected based on the type of temperature-controlled transistor 402 and temperature-controlled MOS transistor 502 in a particular application.
Referring to fig. 9, fig. 9 is a schematic structural diagram of an operational amplifier and a compensation circuit in an operational amplifier structure according to an embodiment of the present disclosure, and for the operational amplifier structure according to the present embodiment, the compensation circuit 201 in the operational amplifier structure includes: the main control transistor P1, the source electrode receives the power supply voltage, the drain electrode is connected with the grid electrode, and the drain electrode is used for receiving the initial compensation current Ios; the first temperature control transistor group 21 comprises a plurality of first temperature control transistors, wherein a source electrode of each first temperature control transistor is connected with a source electrode of the main control transistor P1, a grid electrode is connected with a grid electrode of the main control transistor P1, and drain electrodes of the plurality of first temperature control transistors are connected with each other to generate a first compensation current; the second temperature control transistor group 22 comprises a plurality of second temperature control transistors, wherein the source electrode of each second temperature control transistor is connected with the source electrode of the main control transistor P1, the grid electrode is connected with the grid electrode of the main control transistor P1, and the drain electrodes of the plurality of second temperature control transistors are connected with each other to generate a second compensation current; wherein the first compensation current and the second compensation current form a compensation current pair.
Specifically, if N1 first temperature control transistors are turned on in the first temperature control transistor group 21, the first compensation current value generated at this time is N1×ios; if N2 second temperature control transistors are turned on in the second temperature control transistor group 22, the second compensation current value generated at this time is N2×ios.
It should be noted that, in a specific application, N1 and N2 may be configured to be 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.
With continued reference to fig. 9, with the operational amplifier structure provided in the present embodiment, the operational amplifier 101 includes a first-stage amplification circuit 601 and a second-stage amplification circuit 602. Wherein the first stage amplification circuit 601 is configured to amplify input signals of a positive phase input terminal vin+ and a negative phase input terminal Vin-of the operational amplifier 101 to generate an initial output signal; the second stage amplifying circuit 602 is connected to the first stage amplifying circuit 601, and the second stage amplifying circuit 602 is configured to amplify the initial output signal to generate an output signal, where the first compensation current and the second compensation current form a compensation current pair for compensating the magnitude of the initial output signal.
In one example, the first stage amplification circuit 601 includes: the first switch tube P07, the source is used for receiving the power supply voltage, the grid is used for receiving the first switch signal Vp1; the source electrode of the first P-type transistor P01 is connected to the drain electrode of the first switching tube P07, and the gate electrode is used as the non-inverting input terminal vin+ of the operational amplifier 101; the source electrode of the second P-type transistor P02 is connected with the drain electrode of the first switching tube P07, and the grid electrode is used as the negative phase input end Vin-; the drain of the first P-type transistor P01 and the drain of the second P-type transistor P02 are used to output an initial output signal.
In one example, the second stage amplification circuit 602 includes: a third P-type transistor P03 having a source for receiving a power supply voltage; the source electrode of the fourth P-type transistor P04 is used for receiving power supply voltage, and the grid electrode of the fourth P-type transistor P03 is connected with the grid electrode of the third P-type transistor P03; the source electrode of the fifth P-type transistor P05 is connected with the drain electrode of the third P-type transistor P03, the drain electrode is connected with the grid electrode of the third P-type transistor P03, and the grid electrode is used for receiving the fourth switching signal Vp2; a source of the sixth P-type transistor P06 is connected to the drain of the fourth P-type transistor P04, a gate of the sixth P-type transistor P05 is connected to the gate of the fifth P-type transistor P05, and the drain is used as the output terminal Vout of the operational amplifier 101; the drain electrode of the first N-type transistor N01 is connected with the drain electrode of the fifth P-type transistor P05, the source electrode of the first N-type transistor N01 is connected with the drain electrode of the first P-type transistor P01 and receives the compensation current pair, and the grid electrode of the first N-type transistor N01 is used for receiving the second switching signal Vn2; the drain electrode of the second N-type transistor N02 is connected with the drain electrode of the sixth P-type transistor P06, the source electrode of the second N-type transistor N02 is connected with the drain electrode of the second P-type transistor P02 and receives the compensation current pair, and the grid electrode of the second N-type transistor N01 is connected with the grid electrode of the first N-type transistor; the drain electrode of the third N-type transistor N03 is connected with the source electrode of the first N-type transistor N01, the source electrode is grounded, and the grid electrode is used for receiving a third switching signal Vn1; the drain electrode of the fourth N-type transistor N04 is connected with the source electrode of the second N-type transistor N02, the source electrode is grounded, and the grid electrode is connected with the grid electrode of the third N-type transistor N03.
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 amplifying circuit 602 to form a simpler second stage amplifying circuit.
It should be noted that, the first switching signal Vp1 and the fourth switching signal Vp2 are two signals with the same level or are formed by the same signal; the second switching signal Vn2 and the third switching signal Vn1 are two signals of the same level or are formed by the same signal; the first switching signal Vp1 and the second switching signal Vn2 are two signals of opposite levels or inverted signals of the same signal.
It should also be noted that references to "source" and "drain" in the above description are for exemplary illustration of the type of transistor shown in fig. 9 only; in a specific application, the above-mentioned positions of the "source" and "drain" may be replaced correspondingly if the type of the corresponding transistor is changed.
Based on the foregoing, it is assumed that the operational amplifier structure has an equivalent input offset of Vos, and generally for a well-designed operational amplifier structure, the equivalent input offset mainly results from a mismatch of threshold voltages Vth of the first P-type transistor P01 and the second P-type transistor P02. By initially compensating the current Ios to the drain of the first P-type transistor P01 and the drain of the second P-type transistor P02, the effect of compensating the equivalent input offset Vos can be achieved.
Where 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-controlled transistor group 21 and the second temperature-controlled transistor group 22 to adjust the magnitude of the compensation current based on the initial compensation current Ios.
The mobility of the transistor is inversely related to the temperature, gm is also strongly inversely related to the temperature according to the relationship between gm and mobility, and the temperature coefficient is assumed to be alpha; as can be seen from fig. 6, the initial compensation current Ios provided by the present disclosure includes a constant current Ipp and a temperature control current Ictat, where ictat=vbe/R05, and based on fig. 7 and 8, the temperature control voltage Vbe is generated based on the base region and the emitter voltage of the triode, or based on the drain-source voltage Vgs of the MOS transistor operating in the subthreshold region, so that the temperature control voltage Vbe also has a strong temperature negative correlation, and the correlation is greater than the correlation of gm, assuming that the temperature coefficient is β, and β is greater than a.
After temperature parameters are involved, vos x gm=vos0 x gm0 x (1+a x T), where Vos0 is Vos at absolute 0 degrees and gm0 is gm at absolute 0 degrees; ios=ipp+ictat=k1+ipp+k2+ictat 0 (1+βt), where Ictat0 is Ictat in 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.
The above formula can be found in parallel:
（1）；
（2）；
（3）；
When equations (2) (3) are satisfied, equation (1) is satisfied, that is, equivalent input offset of Vos existing in the op amp structure is completely eliminated, for equation (2), the temperature coefficients a and β, ipp and Ictat0 are known values, the setting parameters of the first resistor R04 and the second resistor R05 can be obtained by equation (2), and then the encoded values of the first temperature control transistor group 21 and the second temperature control transistor group 22 can be obtained by bringing K1 and K2 into equation (3).
It should be noted that, in some embodiments, the constant current Ipp may also be set to a temperature-controlled current that is positively correlated based on temperature; in some embodiments, if the encoding values of the first temperature control transistor group 21 and the second temperature control transistor group 22 are fixed, the values of K1 and K2 may also be determined based on the formulas (2) (3) to completely eliminate the equivalent input offset of Vos existing in the op-amp structure by using only K1 and K2 as adjustment terms; in some embodiments, K1 and K2 may also be adjusted based on the manner in which the current mirror is set.
In summary, by applying the initial compensation current with the negative temperature correlation to the compensation module 102, the compensation module 102 performs the negative temperature correlation on the magnitude of the offset compensation current; when the external temperature changes, the compensation current for completing the mismatch compensation of the transistor saturation region and the compensation current provided by the compensation module 102 are changed in the same direction, so that the operational amplifier offset can be better compensated after being compensated at normal temperature and along with the temperature change.
That is, the operational amplifier structure provided by the present disclosure can reduce operational amplifier offset by a small value in the full temperature range. The high-precision output of the operational amplifier structure is realized by not only realizing mismatch compensation caused by process deviation, but also realizing mismatch compensation caused by temperature change.
It should be noted that the features disclosed in the op-amp structure provided in the above embodiment may be arbitrarily combined without collision, so as to obtain a new op-amp structure embodiment.
Another embodiment of the present disclosure is also used to provide an integrated circuit, in which the operational amplifier structure provided by the foregoing embodiment is disposed.
Referring to fig. 5, the op-amp structure includes: the operational amplifier 101 and the compensation module 102, wherein the compensation module 102 comprises a compensation circuit 201 and a compensation current source 202, wherein the compensation circuit 201 is coupled to the operational amplifier 101, the compensation circuit 201 is configured to generate a compensation current pair based on the initial compensation current Ios, the compensation current pair being used to reduce operational amplifier mismatch of the operational amplifier 101; the compensation current source 202 is coupled to the compensation circuit 201 to provide an initial compensation current Ios; the initial compensation current Ios is synthesized by a constant current Ipp and a temperature control current Ictat, and the magnitude of the temperature control current Ictat is inversely related to the temperature.
It should be noted that the integrated circuit provided in this embodiment may be applied to various types of electronic products, for example, mobile phones, tablet computers, and artificial intelligence hardware devices, and the hardware structure of the practical device should only involve the integrated circuit including the op-amp structure provided in the above embodiment.
It is not difficult to find that this embodiment can be implemented in conjunction with the op amp structure provided in the previous embodiment. The related technical details mentioned in the previous embodiment are still valid in this embodiment, and in order to reduce repetition, they are not repeated here.
It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples of carrying out the application and that various changes in form and details may be made therein without departing from the spirit and scope of the application.
Claims (10)
1. An operational amplifier structure comprising an operational amplifier and a compensation module, wherein the compensation module comprises:
a compensation circuit coupled to the operational amplifier and configured to generate a compensation current pair based on an initial compensation current, the compensation current pair for reducing an operational amplifier mismatch of the operational amplifier;
A compensation current source coupled to the compensation circuit to provide the initial compensation current; the initial compensation current is synthesized by constant current and temperature control current, and the magnitude of the temperature control current is inversely related to the temperature.
2. The op-amp architecture of claim 1 wherein the compensation current source comprises:
The non-inverting input end of the first operational amplifier is used for receiving the reference voltage, and the output end of the first operational amplifier is connected with the grid electrode of the first transistor;
the source electrode of the first transistor is connected with the first end of the first resistor, and is connected with the negative phase input end of the first operational amplifier, and the second end of the first resistor is grounded;
The non-inverting input end of the second operational amplifier is used for receiving the temperature control voltage, and the output end of the second operational amplifier is connected with the grid electrode of the second transistor;
the source electrode of the second transistor is connected with the first end of the second resistor and the negative phase input end of the second operational amplifier, and the second end of the second resistor is grounded;
The drain electrode of the first transistor is used for generating the constant current, the drain electrode of the second transistor is used for generating the temperature control current, and the drain electrode of the first transistor and the drain electrode of the second transistor are connected to synthesize and generate the initial compensation current.
3. The operational amplifier structure according to claim 2, wherein the first resistor and the second resistor are configured as resistors with adjustable resistance values.
4. The op-amp architecture of claim 2 wherein the compensation current source further comprises: and the voltage generation circuit is coupled with the second operational amplifier and is configured to generate the temperature control voltage based on the temperature of the operational amplifier structure, wherein the magnitude of the temperature control voltage is inversely related to the temperature of the operational amplifier structure.
5. The operational amplifier structure of claim 4 wherein the voltage generation circuit comprises:
the temperature control current source is used for receiving the power supply voltage at the input end and outputting the temperature control voltage at the output end;
And the emitting electrode of the temperature control triode is connected with the output end of the temperature control current source, the base electrode of the temperature control triode is connected with the collecting electrode, and the collecting electrode is grounded.
6. The operational amplifier structure of claim 4 wherein the voltage generation circuit comprises:
the temperature control current source is used for receiving the power supply voltage at the input end and outputting the temperature control voltage at the output end;
The grid electrode of the temperature control MOS tube is connected with the drain electrode, the drain electrode is connected with the output end of the temperature control current source, and the source electrode is grounded;
Wherein, the temperature control MOS tube is configured to work in a subthreshold region.
7. The op-amp structure of any one of claims 1-6, wherein the compensation circuit comprises:
The source electrode of the main control transistor receives the power supply voltage, the grid electrode of the main control transistor is connected with the drain electrode, and the drain electrode is used for receiving the initial compensation current;
The first temperature control transistor group comprises a plurality of first temperature control transistors, wherein the source electrode of each first temperature control transistor is connected with the source electrode of the main control transistor, the grid electrode is connected with the grid electrode of the main control transistor, and the drain electrodes of the plurality of first temperature control transistors are connected with each other to generate a first compensation current;
The second temperature control transistor group comprises a plurality of second temperature control transistors, wherein the source electrode of each second temperature control transistor is connected with the source electrode of the main control transistor, the grid electrode of each second temperature control transistor is connected with the grid electrode of the main control transistor, and the drain electrodes of the plurality of second temperature control transistors are connected with each other to generate a second compensation current;
wherein the first compensation current and the second compensation current constitute the compensation current pair.
8. The op-amp structure of any one of claims 1-6, wherein the op-amp comprises:
a first stage amplifying circuit configured to amplify input signals of a positive phase input terminal and a negative phase input terminal of the operational amplifier to generate an initial output signal;
a second stage amplifying circuit connected to the first stage amplifying circuit and configured to amplify the initial output signal to generate an output signal;
wherein the compensation current pair is used to compensate for the magnitude of the initial output signal.
9. The op-amp structure of claim 8, comprising:
the first stage amplifying circuit includes:
the first switch tube comprises a source electrode for receiving a power supply voltage and a grid electrode for receiving a first switch signal;
the source electrode of the first P-type transistor is connected with the drain electrode of the first switching tube, and the grid electrode of the first P-type transistor is used as the non-inverting input end of the operational amplifier;
The source electrode of the second P-type transistor is connected with the drain electrode of the first switching tube, and the grid electrode of the second P-type transistor is used as the negative phase input end of the operational amplifier;
The drain electrode of the first P-type transistor and the drain electrode of the second P-type transistor are used for outputting the initial output signal;
the second-stage amplification circuit includes:
the source electrode of the third P-type transistor is used for receiving a power supply voltage;
the source electrode of the fourth P-type transistor is used for receiving power supply voltage, and the grid electrode of the fourth P-type transistor is connected with the grid electrode of the third P-type transistor;
A fifth P-type transistor, wherein the source electrode is connected with the drain electrode of the third P-type transistor, and the drain electrode is connected with the grid electrode and the grid electrode of the third P-type transistor;
a sixth P-type transistor, wherein the source electrode is connected with the drain electrode of the fourth P-type transistor, the grid electrode is connected with the grid electrode of the fifth P-type transistor, and the drain electrode is used as the output end of the operational amplifier;
the drain electrode of the first N-type transistor is connected with the drain electrode of the fifth P-type transistor, the source electrode of the first N-type transistor is connected with the drain electrode of the first P-type transistor and receives the compensation current pair, and the grid electrode of the first N-type transistor is used for receiving a second switching signal;
The drain electrode of the second N-type transistor is connected with the drain electrode of the sixth P-type transistor, the source electrode of the second N-type transistor is connected with the drain electrode of the second P-type transistor and receives the compensation current pair, and the grid electrode of the second N-type transistor is connected with the grid electrode of the first N-type transistor;
The drain electrode of the third N-type transistor is connected with the source electrode of the first N-type transistor, the source electrode is grounded, and the grid electrode is used for receiving a third switching signal;
And the drain electrode of the fourth N-type transistor is connected with the source electrode of the second N-type transistor, the source electrode is grounded, and the grid electrode of the fourth N-type transistor is connected with the grid electrode of the third N-type transistor.
10. An integrated circuit, wherein the operational amplifier structure of any one of claims 1 to 9 is provided in the integrated circuit.
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