CN114123988A - Constant transconductance rail-to-rail input and output operational amplifier - Google Patents
Constant transconductance rail-to-rail input and output operational amplifier Download PDFInfo
- Publication number
- CN114123988A CN114123988A CN202111440330.9A CN202111440330A CN114123988A CN 114123988 A CN114123988 A CN 114123988A CN 202111440330 A CN202111440330 A CN 202111440330A CN 114123988 A CN114123988 A CN 114123988A
- Authority
- CN
- China
- Prior art keywords
- transistor
- input
- rail
- current
- operational amplifier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000002829 reductive effect Effects 0.000 claims description 34
- 239000013589 supplement Substances 0.000 claims description 27
- 230000009467 reduction Effects 0.000 claims description 8
- 230000003313 weakening effect Effects 0.000 claims description 7
- 230000007423 decrease Effects 0.000 claims description 5
- 230000003247 decreasing effect Effects 0.000 claims description 2
- 230000008859 change Effects 0.000 abstract description 6
- 238000013459 approach Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000003068 static effect Effects 0.000 description 4
- 230000001502 supplementing effect Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
Images
Classifications
-
- 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
- H03F1/301—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in MOSFET amplifiers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45179—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using MOSFET transistors as the active amplifying circuit
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45051—Two or more differential amplifiers cascade coupled
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
Abstract
The invention discloses a constant transconductance rail-to-rail input and output operational amplifier which comprises an operational amplifier circuit to be stabilized and an auxiliary circuit. The auxiliary circuit is connected between a power supply rail and a ground rail of the operational amplifier circuit to be stabilized, a first input end of the auxiliary circuit is connected with tail current output ends of differential pair transistors pm1 and pm2 of the operational amplifier circuit to be stabilized, a second input end of the auxiliary circuit is connected with tail current output ends of differential pair transistors nm1 and nm2 of the operational amplifier circuit to be stabilized, a first output end of the auxiliary circuit is connected with an input end of a transistor pm13 of the operational amplifier circuit to be stabilized, and a second output end of the auxiliary circuit is connected with an input end of a transistor pm14 of the operational amplifier circuit to be stabilized. According to the scheme, the auxiliary circuit is additionally arranged in the circuit of the original constant transconductance rail-to-rail input and output operational amplifier to eliminate the change of the bias state of the output stage of the constant transconductance rail-to-rail input and output operational amplifier when the input common mode level changes, and the operational amplifier bandwidth, the phase margin and the overall power consumption of the constant transconductance rail-to-rail input and output operational amplifier are stabilized.
Description
Technical Field
The invention relates to the technical field of integrated circuit design, in particular to a constant transconductance rail-to-rail input and output operational amplifier.
Background
Constant transconductance rail-to-rail input-output operational amplifiers are often used in integrated circuit designs. At present, the operational amplifier circuit structure of the constant transconductance rail-to-rail input and output operational amplifier is shown in fig. 1, and comprises two input differential pair transistors nm1, nm2 (a pair of N-MOS transistors) and pm1, pm2 (a pair of P-MOS transistors), and the input common mode voltage VCMIN ═ v (VIM + VIP)/2 of the operational amplifier circuit should satisfy VSS < VCMIN < VDD. In the circuit:
when the input common-mode voltage VCMIN is close to the power supply rail voltage VDD, the differential pair transistors pm1 and pm2 are turned off, the differential pair transistors nm1 and nm2 work, tail currents of the differential pair transistors pm1 and pm2 flow to the transistor nm6 through the transistor pm3, mirror images of the transistors nm6/nm5 are superposed on the differential pair transistors nm1 and nm2 to serve as tail current sources, bias currents of the differential pair transistors nm1 and nm2 are increased, and the integral transconductance of the operational amplifier is kept constant. However, at this time, more current of the current sources pm8 and pm9 flows to the differential pair transistors nm1 and nm2, so that the current flowing to the transistors pm13 and pm14 is reduced, further the current flowing through the transistors pm7 and nm7 is reduced, the gate-source voltage of the transistors pm7 and nm7 is reduced, the gate-source voltage of the output stage transistors pm15 and nm15 is increased, the static bias current of the output stage transistors pm15 and nm15 is increased, the transconductance is increased, the bandwidth and the phase margin of the operational amplifier are increased, and the static power consumption is also increased.
When the input common-mode voltage VCMIN approaches to the ground rail voltage VSS, the differential pair transistors nm1 and nm2 are turned off, tail currents of the differential pair transistors nm1 and nm2 flow to the transistor pm6 after passing through the transistor nm3, mirror images of the transistors pm6 and pm5 are superposed on the differential pair transistors pm1 and pm2, the tail currents of the differential pair transistors pm1 and pm2 are increased, transconductance of the differential pair transistors pm1 and pm2 is increased, and the integral transconductance of the operational amplifier is kept constant. However, at this time, the current of the current sources pm8 and pm9 originally flows through the parts of the differential pair transistors nm1 and nm2, flows to the transistors pm13 and pm14, the currents of the transistors pm13 and pm14 are increased, the currents of the transistors pm7 and nm7 are increased, the gate-source voltages of the transistors pm7 and nm7 are increased, the gate-source voltages of the output stage transistors pm15 and nm15 are reduced, the static currents flowing through the output stage transistors pm15 and nm15 are reduced, the transconductance of the output stage transistors pm15 and nm15 is reduced, the bandwidth and the phase margin of the operational amplifier are reduced, and the static power consumption is also reduced.
Based on the above analysis, in the conventional constant transconductance rail-to-rail input and output operational amplifier, under different input common mode voltages, the output stage has different bias states, which causes different transconductance and power consumption of the output stage, so that the bandwidth, the phase margin and the power consumption of the operational amplifier are greatly changed.
Disclosure of Invention
The invention provides a constant transconductance rail-to-rail input and output operational amplifier provided with an auxiliary circuit, aiming at solving the technical problems of unstable output stage bias state, transconductance and power consumption of the conventional constant transconductance rail-to-rail input and output operational amplifier.
In order to solve the technical problems, the invention provides the following technical scheme:
the embodiment of the invention provides a constant transconductance rail-to-rail input and output operational amplifier, which comprises an operational amplifier circuit to be stabilized and an auxiliary circuit, wherein:
the auxiliary circuit is connected between a power supply rail and a ground rail of the operational amplifier circuit to be stabilized, a first input end of the auxiliary circuit is connected with tail current output ends of differential pair transistors pm1 and pm2 of the operational amplifier circuit to be stabilized, a second input end of the auxiliary circuit is connected with tail current output ends of differential pair transistors nm1 and nm2 of the operational amplifier circuit to be stabilized, a first output end of the auxiliary circuit is connected with an input end of a transistor pm13 of the operational amplifier circuit to be stabilized, and a second output end of the auxiliary circuit is connected with an input end of a transistor pm14 of the operational amplifier circuit to be stabilized;
when the differential pair transistors pm1, pm2 are turned off and the current at the input terminals of the transistors pm13, pm14 is reduced, the auxiliary circuit supplements the current to the input terminals of the transistors pm13, pm 14; when the differential pair transistors nm1 and nm2 are turned off and the input current of the transistors pm13 and pm14 is increased, the auxiliary circuit attenuates the input current of the transistors pm13 and pm 14.
In the constant transconductance rail-to-rail input and output operational amplifier described in some embodiments of the present invention, a first input terminal of the auxiliary circuit is connected to an input terminal of the transistor nm6 of the operational amplifier circuit to be stabilized, and a second input terminal of the auxiliary circuit is connected to an input terminal of the transistor pm6 of the operational amplifier circuit to be stabilized;
when the input currents of transistor pm13 and transistor pm14 decrease, the input current of transistor nm6 increases, and the auxiliary circuit supplements the input current of transistor pm13 and transistor pm14 with the increased current at the input of transistor nm 6;
when the input current to transistor pm13 and transistor pm14 increases, the input current to transistor pm6 decreases and the auxiliary circuit attenuates the current at the input of transistors pm13 and pm14 with the current at the input of transistor pm6 decreasing.
In some embodiments of the invention, the constant transconductance rail-to-rail input-output operational amplifier comprises:
the input end of the current supplement circuit is connected with the input end of the transistor nm6 of the operational amplifier circuit to be stabilized, the first output end of the current supplement circuit is connected with the first output end of the auxiliary circuit, and the second output end of the current supplement circuit is connected with the second output end of the auxiliary circuit; when the current at the input end of the transistor nm6 is increased, and the input currents of the transistor pm13 and the transistor pm14 are reduced, the current increased at the input end of the transistor nm6 is output to the transistor pm13 and the transistor pm14 through the current supplement circuit, so that the current flowing through the transistor pm13 and the transistor pm14 is ensured to be a constant value.
In some embodiments of the invention, the constant transconductance rail-to-rail input-output operational amplifier further comprises:
the input end of the current weakening circuit is connected with the input end of the transistor pm6 of the operational amplifier circuit to be stabilized, the first output end of the current weakening circuit is connected with the first output end of the auxiliary circuit, and the second output end of the current weakening circuit is connected with the second output end of the auxiliary circuit; when the input current of the transistor pm6 is reduced, and the input currents of the transistor pm13 and the transistor pm14 are increased, the current reduced at the input end of the transistor pm6 flows through the current reduction circuit to be output to the transistor pm13 and the transistor pm14, so that the current flowing through the transistor pm13 and the transistor pm14 is ensured to be a constant value.
The constant transconductance rail-to-rail input and output operational amplifier provided by the embodiment of the invention is characterized in that the current supplement circuit comprises a transistor nm20, the transistor nm20 is in mirror image connection with the transistor nm6, and the increased current at the input end of the transistor nm6 is in mirror image connection with the current supplement circuit through the transistor nm 20.
In some embodiments of the present invention, the constant transconductance rail-to-rail input-output operational amplifier further comprises a transistor pm21, a pair of mirror transistors pm22 and pm 23;
the input of transistor pm21 is connected with the output of transistor nm20, and a pair of the input of mirror image transistors pm22 and pm23 is connected with the end of the output of transistor pm21, the output of transistor pm22 is connected with the input of transistor pm14, and the output of transistor pm23 is connected with the input of transistor pm 13.
In some embodiments of the invention, the constant transconductance rail-to-rail input and output operational amplifier comprises a transistor pm20, and the transistor pm20 is connected with the transistor pm6 in a mirror mode; the reduced current at the input of transistor pm6 is mirrored through transistor pm20 into the current sourced droop circuit.
The constant transconductance rail-to-rail input-output operational amplifier described in some embodiments of the present invention, the current reduction circuit further comprises a transistor nm21, a pair of mirror transistors nm22 and nm 23;
the input end of the transistor nm21 is connected with the output end of the transistor pm20, the input ends of the pair of mirror image transistors nm22 and nm23 are connected with the output end of the transistor nm21, the output end of the transistor nm22 is connected with the input end of the transistor pm13, and the output end of the transistor nm23 is connected with the input end of the transistor pm 14.
In the constant transconductance rail-to-rail input-output operational amplifier described in some embodiments of the present invention, the sources of the transistor pm20, the transistor pm21, the transistor pm22, and the transistor pm23 are all connected to the voltage rail.
In the constant transconductance rail-to-rail input-output operational amplifier described in some embodiments of the present invention, the sources of the transistor nm20, the transistor nm21, the transistor nm22, and the transistor nm23 are all connected to the ground rail.
Compared with the prior art, the technical scheme of the invention has the following technical effects:
the constant transconductance rail-to-rail input and output operational amplifier provided by the invention takes a circuit in the conventional constant transconductance rail-to-rail input and output operational amplifier as an operational amplifier circuit to be stabilized, and an auxiliary circuit is additionally arranged on the basis of the operational amplifier circuit to be stabilized. The auxiliary circuit is connected between a power supply rail and a ground rail of the operational amplifier circuit to be stabilized, a first input end of the auxiliary circuit is connected with tail current output ends of differential pair transistors pm1 and pm2 of the operational amplifier circuit to be stabilized, a second input end of the auxiliary circuit is connected with tail current output ends of differential pair transistors nm1 and nm2 of the operational amplifier circuit to be stabilized, a first output end of the auxiliary circuit is connected with an input end of a transistor pm13 of the operational amplifier circuit to be stabilized, and a second output end of the auxiliary circuit is connected with an input end of a transistor pm14 of the operational amplifier circuit to be stabilized; when the differential pair transistors pm1, pm2 are turned off and the currents at the input terminals of the transistors pm13, pm14 are reduced, the auxiliary circuit supplements the currents to the input terminals of the transistors pm13, pm 14; when the differential pair transistors nm1, nm2 are turned off and the input current of the transistors pm13, pm14 increases, the auxiliary circuit attenuates the input current of the transistors pm13, pm 14. By the scheme, when the input common mode voltage VCMIN of the operational amplifier circuit to be stabilized is close to the power rail voltage VDD and the transistors pm1 and pm2 in the operational amplifier circuit to be stabilized are turned off, tail currents of the transistors pm1 and pm2 supplement the reduced currents of the transistors pm13 and pm14 back through the added auxiliary circuit through the transistor pm3, and the currents flowing through the transistors pm13 and pm14 are kept constant. When the input common mode voltage VCMIN of the operational amplifier circuit to be stabilized is close to the ground rail voltage VSS, the transistors nm1 and nm2 are turned off, tail currents of the transistors nm1 and nm2 pass through the transistor nm3, the auxiliary circuit subtracts currents added by the transistors pm13 and pm14 correspondingly, and the currents flowing through the transistors pm13 and pm14 are kept constant. According to the scheme, the change of the bias state of the output stage of the constant transconductance rail-to-rail input and output operational amplifier when the input common mode level changes is eliminated, the functions of stabilizing the operational amplifier bandwidth, the phase margin and the overall power consumption of the constant transconductance rail-to-rail input and output operational amplifier are achieved, and the operational amplifier bandwidth, the phase margin and the power consumption of the constant transconductance rail-to-rail input and output operational amplifier are enabled not to change along with the input common mode voltage.
Drawings
The objects and advantages of the present invention will be understood by the following detailed description of the preferred embodiments of the invention, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic circuit diagram of a conventional constant transconductance rail-to-rail input/output operational amplifier;
FIG. 2 is a circuit diagram of a constant transconductance rail-to-rail input-output operational amplifier according to an embodiment of the invention;
FIG. 3 is a schematic diagram of the auxiliary circuit according to an embodiment of the present invention;
fig. 4 is a circuit diagram of a constant transconductance rail-to-rail input-output operational amplifier according to another embodiment of the invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The present embodiment provides a constant transconductance rail-to-rail input/output operational amplifier, as shown in fig. 2, including an operational amplifier circuit 10 to be stabilized and an auxiliary circuit 20. Wherein, the auxiliary circuit 20 is connected between the power rail and the ground rail of the operational amplifier circuit to be stabilized 10. The auxiliary circuit 20 is connected between a power supply rail and a ground rail of the operational amplifier circuit 10 to be stabilized, a first input end of the auxiliary circuit is connected with tail current output ends of differential pair transistors pm1 and pm2 of the operational amplifier circuit 10 to be stabilized, a second input end of the auxiliary circuit is connected with tail current output ends of differential pair transistors nm1 and nm2 of the operational amplifier circuit 10 to be stabilized, a first output end of the auxiliary circuit is connected with an input end of a transistor pm13 of the operational amplifier circuit 10 to be stabilized, and a second output end of the auxiliary circuit is connected with an input end of a transistor pm14 of the operational amplifier circuit 10 to be stabilized; when the differential pair transistors pm1, pm2 are turned off and the current at the input terminals of the transistors pm13, pm14 is reduced, the auxiliary circuit supplements the current to the input terminals of the transistors pm13, pm 14; when the differential pair transistors nm1 and nm2 are turned off and the input current of the transistors pm13 and pm14 is increased, the auxiliary circuit attenuates the input current of the transistors pm13 and pm 14.
Specifically, the first input end of the auxiliary circuit 20 is connected to the input end of the transistor nm6 of the operational amplifier circuit 10 to be stabilized, the second input end of the auxiliary circuit 20 is connected to the input end of the transistor pm6 of the operational amplifier circuit 10 to be stabilized, the first output end of the auxiliary circuit 20 is connected to the input end of the transistor pm13 of the operational amplifier circuit 10 to be stabilized, and the second output end of the auxiliary circuit 20 is connected to the input end of the transistor pm14 of the operational amplifier circuit 10 to be stabilized. When the input currents of the transistor pm13 and the transistor pm14 are reduced, the current at the input end of the transistor nm6 of the operational amplifier circuit to be stabilized is increased, and the auxiliary circuit 20 supplements the current at the input end of the transistor nm6 to the input ends of the transistor pm13 and the transistor pm 14; when the input current of the transistor pm13 and the transistor pm14 is increased, the current at the input end of the transistor pm6 of the operational amplifier circuit 10 to be stabilized is reduced, and the auxiliary circuit 20 attenuates the current at the input end of the transistor pm13 and the input end of the transistor pm14 by the reduced current at the input end of the transistor pm 6.
A circuit in a conventional constant transconductance rail-to-rail input and output operational amplifier is used as the operational amplifier circuit 10 to be stabilized, and an auxiliary circuit 20 is additionally arranged on the basis of the operational amplifier circuit 10 to be stabilized. When the input common mode voltage VCMIN of the operational amplifier circuit 10 to be stabilized approaches the power rail voltage VDD, and the transistors pm1 and pm2 in the operational amplifier circuit 10 to be stabilized are turned off, tail currents of the transistors pm1 and pm2 flow to the transistor nm6 through the transistor pm3, and then reduced currents of the transistors pm13 and pm14 are supplemented back through the added auxiliary circuit 20, so that the currents flowing through the transistors pm13 and pm14 are kept constant. When the input common mode voltage VCMIN of the operational amplifier circuit 10 to be stabilized approaches the ground rail voltage VSS, the transistors nm1 and nm2 are turned off, tail currents of the transistors nm1 and nm2 flow to the transistor pm6 through the transistor nm3, and then the currents added by the transistors pm13 and pm14 are correspondingly subtracted through the added auxiliary circuit 20, so that the currents flowing through the transistors pm13 and pm14 are kept constant.
The scheme in the embodiment eliminates the change of the bias state of the output stage when the input common mode level of the constant transconductance rail-to-rail input and output operational amplifier changes, and plays a role in stabilizing the operational amplifier bandwidth, the phase margin and the overall power consumption of the constant transconductance rail-to-rail input and output operational amplifier, so that the operational amplifier bandwidth, the phase margin and the power consumption of the constant transconductance rail-to-rail input and output operational amplifier do not change along with the input common mode voltage.
Further, as shown in fig. 3, the auxiliary circuit 20 may include a current supplement circuit 21, an input terminal of which is connected to the input terminal of the transistor nm6 of the operational amplifier circuit to be stabilized 10 (i.e., an input terminal of the current supplement circuit 21 may be connected to a first input terminal of the auxiliary circuit 20), a first output terminal of which is connected to a first output terminal of the auxiliary circuit 20, and a second output terminal of which is connected to a second output terminal of the auxiliary circuit 20; when the input current of the transistor nm6 is increased and the input currents of the transistor pm13 and the transistor pm14 are reduced, the current increased at the input end of the transistor nm6 is output to the transistor pm13 and the transistor pm14 through the current supplementing circuit 21, so that the current flowing through the transistor pm13 and the transistor pm14 is ensured to be a constant value. The auxiliary circuit 20 may further include a current reduction circuit 22, an input terminal of which is connected to the input terminal of the transistor pm6 of the operational amplifier circuit to be stabilized (i.e., an input terminal of the current reduction circuit 22 may be connected to a second input terminal of the auxiliary circuit 20), a first output terminal of which is connected to the first output terminal of the auxiliary circuit 20, and a second output terminal of which is connected to the second output terminal of the auxiliary circuit 20; when the input current of the transistor pm6 is reduced, and the input currents of the transistor pm13 and the transistor pm14 are increased, the current reduced at the input end of the transistor pm6 flows through the current reduction circuit to be output to the transistor pm13 and the transistor pm14, so that the current flowing through the transistor pm13 and the transistor pm14 is ensured to be a constant value.
In the scheme, the current reduced by the transistor pm13 and the current reduced by the transistor pm14 are directly supplemented back by the current supplementing circuit 21 in an equal amount, and the current increased by the transistor pm13 and the current increased by the transistor pm14 are directly subtracted by the current weakening circuit 22 in an equal amount, so that the stability of the bias state of the output stage of the constant transconductance rail-to-rail input and output operational amplifier can be ensured when any change of the common mode input voltage occurs.
Preferably, as shown in fig. 4, in the constant transconductance rail-to-rail input-output operational amplifier, the current supplement circuit 21 comprises a transistor nm20, the transistor nm20 is in mirror connection with the transistor nm6, and the increased current at the input end of the transistor nm6 is in mirror connection with the current supplement circuit through the transistor nm 20. The current supplementing circuit 21 further includes a transistor pm21, a pair of mirror transistors pm22 and pm 23; the input of transistor pm21 with the output of transistor nm20 is connected, and is a pair the input of mirror image transistors pm22 and pm23 with the end of the output of transistor pm21 is connected, the output of transistor pm22 with the input of transistor pm14 is connected, the output of transistor pm23 with the input of transistor pm13 is connected, wherein, transistor pm20, transistor pm21, transistor pm22 and the source of transistor pm23 all are connected to the voltage rail. As shown in the figure, when the input common mode voltage VCMIN of the constant transconductance rail-to-rail input-output operational amplifier approaches the power rail voltage VDD, the differential pair transistors pm1 and pm2 are turned off, the tail current of the differential pair transistors pm1 and pm2 flows to the transistor nm6 through the transistor pm3, the transistor nm6 flows to the differential pair transistors nm1 and nm2 through the transistor nm5 mirror image, the transconductance of the differential pair transistors nm1 and nm2 is increased, and the overall transconductance of the operational amplifier is kept constant. The current flowing through the differential pair transistors nm1, nm2 increases, resulting in a decrease in the current flowing through the transistors pm13, pm14, while the current flowing through the transistor nm6 is mirrored to the transistor pm21 via the newly added transistor nm20 in the auxiliary circuit 20, and the transistor pm 4 supplements the current reduced by the transistors pm13, pm14 back via the transistors pm22, pm23 mirror, keeping the current flowing through the transistors pm13, pm14 constant.
Further, as shown in fig. 4, in the constant transconductance rail-to-rail input-output operational amplifier, the current reduction circuit 22 includes a transistor pm20, and the transistor pm20 is connected with the transistor pm6 in a mirror image manner; the reduced current at the input of transistor pm6 is mirrored through transistor pm20 into the current sourced droop circuit. Wherein the current de-emphasis circuit 22 further comprises a transistor nm21, a pair of mirror transistors nm22 and nm 23; the input end of the transistor nm21 is connected with the output end of the transistor pm20, the input ends of the pair of mirror transistors nm22 and nm23 are connected with the output end of the transistor nm21, the output end of the transistor nm22 is connected with the input end of the transistor pm13, the output end of the transistor nm23 is connected with the input end of the transistor pm14, wherein the sources of the transistor nm20, the transistor nm21, the transistor nm22 and the transistor nm23 are all connected to the ground rail. As shown, when the input common mode voltage VCMIN of the constant transconductance rail-to-rail input-output operational amplifier approaches the ground rail voltage VSS, the differential pair transistors nm1 and nm2 are turned off, tail currents of the differential pair transistors nm1 and nm2 flow to the transistor pm6 through the transistor nm3, the transistor pm6 mirrors the currents to the differential pair transistors pm1 and pm2 through the transistor pm5, transconductance of the differential pair transistors pm1 and pm2 is increased, and therefore the overall transconductance of the operational amplifier is kept constant. Meanwhile, the currents of the transistors pm13 and pm14 are increased due to the fact that the differential pair transistors nm1 and nm2 are turned off, the transistor pm6 mirrors the current to the transistor nm21 through the newly added transistor pm20 in the auxiliary circuit 20, the transistors nm22 and nm23 mirror the current of the transistor nm21, the currents added by the transistors pm13 and pm14 are correspondingly subtracted, and the currents of the transistors pm13 and pm14 are kept constant.
In the above embodiment of the present invention, the constant transconductance rail-to-rail input and output operational amplifier supplements the reduced current of the transistors pm13 and pm14 back when the differential pair transistors pm1 and pm2 are turned off; when the differential pair nm1 and nm2 is turned off, the currents increased by the transistors pm13 and pm14 are correspondingly reduced, so that the currents flowing through the transistors pm13 and pm14 can be kept unchanged no matter whether the input common mode voltage VCMIN is close to the power supply rail voltage VDD or close to the ground rail voltage VSS, the currents of the transistors pm7 and nm7 are kept unchanged, the bias voltages, the bias currents and the transconductance of the output stage transistors pm15 and nm15 are kept unchanged, and the operational amplifier bandwidth, the phase margin and the power consumption of the constant transconductance rail-to-rail input and output operational amplifier are kept unchanged.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are intended to be within the scope of the invention.
Claims (10)
1. A constant transconductance rail-to-rail input-output operational amplifier, comprising an operational amplifier circuit to be stabilized and an auxiliary circuit, wherein:
the auxiliary circuit is connected between a power supply rail and a ground rail of the operational amplifier circuit to be stabilized, a first input end of the auxiliary circuit is connected with tail current output ends of differential pair transistors pm1 and pm2 of the operational amplifier circuit to be stabilized, a second input end of the auxiliary circuit is connected with tail current output ends of differential pair transistors nm1 and nm2 of the operational amplifier circuit to be stabilized, a first output end of the auxiliary circuit is connected with an input end of a transistor pm13 of the operational amplifier circuit to be stabilized, and a second output end of the auxiliary circuit is connected with an input end of a transistor pm14 of the operational amplifier circuit to be stabilized;
when the differential pair transistors pm1, pm2 are turned off and the current at the input terminals of the transistors pm13, pm14 is reduced, the auxiliary circuit supplements the current to the input terminals of the transistors pm13, pm 14; when the differential pair transistors nm1 and nm2 are turned off and the input current of the transistors pm13 and pm14 is increased, the auxiliary circuit attenuates the input current of the transistors pm13 and pm 14.
2. The constant transconductance rail-to-rail input-output operational amplifier of claim 1, wherein:
the first input end of the auxiliary circuit is connected with the input end of the transistor nm6 of the operational amplifier circuit to be stabilized, and the second input end of the auxiliary circuit is connected with the input end of the transistor pm6 of the operational amplifier circuit to be stabilized;
when the input currents of transistor pm13 and transistor pm14 decrease, the input current of transistor nm6 increases, and the auxiliary circuit supplements the input current of transistor pm13 and transistor pm14 with the increased current at the input of transistor nm 6;
when the input current to transistor pm13 and transistor pm14 increases, the input current to transistor pm6 decreases and the auxiliary circuit attenuates the current at the input of transistors pm13 and pm14 with the current at the input of transistor pm6 decreasing.
3. The constant transconductance rail-to-rail input-output operational amplifier of claim 2, wherein the auxiliary circuit comprises:
the input end of the current supplement circuit is connected with the input end of the transistor nm6 of the operational amplifier circuit to be stabilized, the first output end of the current supplement circuit is connected with the first output end of the auxiliary circuit, and the second output end of the current supplement circuit is connected with the second output end of the auxiliary circuit; when the current at the input end of the transistor nm6 is increased, and the input currents of the transistor pm13 and the transistor pm14 are reduced, the current increased at the input end of the transistor nm6 is output to the transistor pm13 and the transistor pm14 through the current supplement circuit, so that the current flowing through the transistor pm13 and the transistor pm14 is ensured to be a constant value.
4. The constant transconductance rail-to-rail input-output operational amplifier of claim 3, wherein the auxiliary circuit further comprises:
the input end of the current weakening circuit is connected with the input end of the transistor pm6 of the operational amplifier circuit to be stabilized, the first output end of the current weakening circuit is connected with the first output end of the auxiliary circuit, and the second output end of the current weakening circuit is connected with the second output end of the auxiliary circuit; when the input current of the transistor pm6 is reduced, and the input currents of the transistor pm13 and the transistor pm14 are increased, the current reduced at the input end of the transistor pm6 flows through the current reduction circuit to be output to the transistor pm13 and the transistor pm14, so that the current flowing through the transistor pm13 and the transistor pm14 is ensured to be a constant value.
5. The constant transconductance rail-to-rail input-output operational amplifier of claim 4, wherein:
the current supplement circuit comprises a transistor nm20, the transistor nm20 is connected with the transistor nm6 in a mirror image mode, and the increased current at the input end of the transistor nm6 is connected to the current supplement circuit in a mirror image mode through the transistor nm 20.
6. The constant transconductance rail-to-rail input-output operational amplifier of claim 5, wherein:
the current supplement circuit further comprises a transistor pm21, a pair of mirror transistors pm22 and pm 23;
the input of transistor pm21 is connected with the output of transistor nm20, and a pair of the input of mirror image transistors pm22 and pm23 is connected with the end of the output of transistor pm21, the output of transistor pm22 is connected with the input of transistor pm14, and the output of transistor pm23 is connected with the input of transistor pm 13.
7. The constant transconductance rail-to-rail input-output operational amplifier of any one of claims 4-6, wherein:
the current sourced circuit comprises a transistor pm20, the transistor pm20 being mirrored with the transistor pm 6; the reduced current at the input of transistor pm6 is mirrored through transistor pm20 into the current sourced droop circuit.
8. The constant transconductance rail-to-rail input-output operational amplifier of claim 7, wherein:
the current reduction circuit further comprises a transistor nm21, a pair of mirror transistors nm22 and nm 23;
the input end of the transistor nm21 is connected with the output end of the transistor pm20, the input ends of the pair of mirror image transistors nm22 and nm23 are connected with the output end of the transistor nm21, the output end of the transistor nm22 is connected with the input end of the transistor pm13, and the output end of the transistor nm23 is connected with the input end of the transistor pm 14.
9. The constant transconductance rail-to-rail input-output operational amplifier of claim 8, wherein:
the sources of the transistor pm20, the transistor pm21, the transistor pm22, and the transistor pm23 are all connected to the voltage rail.
10. The constant transconductance rail-to-rail input-output operational amplifier of claim 9, wherein:
the sources of the transistor nm20, the transistor nm21, the transistor nm22, and the transistor nm23 are all connected to the ground rail.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111440330.9A CN114123988B (en) | 2021-11-30 | 2021-11-30 | Constant cross-guide rail to rail input/output operational amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111440330.9A CN114123988B (en) | 2021-11-30 | 2021-11-30 | Constant cross-guide rail to rail input/output operational amplifier |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114123988A true CN114123988A (en) | 2022-03-01 |
| CN114123988B CN114123988B (en) | 2024-02-23 |
Family
ID=80368425
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111440330.9A Active CN114123988B (en) | 2021-11-30 | 2021-11-30 | Constant cross-guide rail to rail input/output operational amplifier |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114123988B (en) |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4766394A (en) * | 1986-09-10 | 1988-08-23 | Nec Corporation | Operational amplifier circuit having wide operating range |
| US5311145A (en) * | 1993-03-25 | 1994-05-10 | North American Philips Corporation | Combination driver-summing circuit for rail-to-rail differential amplifier |
| US5371474A (en) * | 1992-05-08 | 1994-12-06 | Philips Electronics North America Corporation | Differential amplifier having rail-to-rail input capability and square-root current control |
| US5550510A (en) * | 1994-12-27 | 1996-08-27 | Lucent Technologies Inc. | Constant transconductance CMOS amplifier input stage with rail-to-rail input common mode voltage range |
| US5734297A (en) * | 1996-03-29 | 1998-03-31 | Philips Electronics North America Corporation | Rail-to-rail input stages with constant gm and constant common-mode output currents |
| WO2005006543A1 (en) * | 2003-07-10 | 2005-01-20 | Koninklijke Philips Electronics N.V. | Systematic offset free operational amplifier and apparatus comprising such an operational amplifier |
| KR20080028600A (en) * | 2006-09-27 | 2008-04-01 | 삼성전자주식회사 | Averaging circuit having offset compensation circuit |
| US20090251214A1 (en) * | 2008-04-02 | 2009-10-08 | Spectralinear, Inc. | Rail-to-rail operational amplifier |
| CN106059516A (en) * | 2016-06-03 | 2016-10-26 | 西安电子科技大学 | Rail-to-rail operational amplifier circuit, ADC converter, DCDC converter and power amplifier |
| CN106341092A (en) * | 2016-08-18 | 2017-01-18 | 苏州源智宇电子科技有限公司 | Low-voltage and low-power-consumption operational amplifier |
| CN109756192A (en) * | 2018-11-22 | 2019-05-14 | 合肥市芯海电子科技有限公司 | A kind of input stage of the rail-to-rail mutual conductance amplifying circuit of reliable low pressure |
| CN111294001A (en) * | 2020-03-24 | 2020-06-16 | 中国科学院微电子研究所 | Rail-to-rail operational amplifier |
-
2021
- 2021-11-30 CN CN202111440330.9A patent/CN114123988B/en active Active
Patent Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4766394A (en) * | 1986-09-10 | 1988-08-23 | Nec Corporation | Operational amplifier circuit having wide operating range |
| US5371474A (en) * | 1992-05-08 | 1994-12-06 | Philips Electronics North America Corporation | Differential amplifier having rail-to-rail input capability and square-root current control |
| US5311145A (en) * | 1993-03-25 | 1994-05-10 | North American Philips Corporation | Combination driver-summing circuit for rail-to-rail differential amplifier |
| US5550510A (en) * | 1994-12-27 | 1996-08-27 | Lucent Technologies Inc. | Constant transconductance CMOS amplifier input stage with rail-to-rail input common mode voltage range |
| US5734297A (en) * | 1996-03-29 | 1998-03-31 | Philips Electronics North America Corporation | Rail-to-rail input stages with constant gm and constant common-mode output currents |
| TW200518019A (en) * | 2003-07-10 | 2005-06-01 | Koninkl Philips Electronics Nv | Systematic offset free operational amplifier and apparatus comprising such an operational amplifier |
| WO2005006543A1 (en) * | 2003-07-10 | 2005-01-20 | Koninklijke Philips Electronics N.V. | Systematic offset free operational amplifier and apparatus comprising such an operational amplifier |
| KR20080028600A (en) * | 2006-09-27 | 2008-04-01 | 삼성전자주식회사 | Averaging circuit having offset compensation circuit |
| US20090251214A1 (en) * | 2008-04-02 | 2009-10-08 | Spectralinear, Inc. | Rail-to-rail operational amplifier |
| CN106059516A (en) * | 2016-06-03 | 2016-10-26 | 西安电子科技大学 | Rail-to-rail operational amplifier circuit, ADC converter, DCDC converter and power amplifier |
| CN106341092A (en) * | 2016-08-18 | 2017-01-18 | 苏州源智宇电子科技有限公司 | Low-voltage and low-power-consumption operational amplifier |
| CN109756192A (en) * | 2018-11-22 | 2019-05-14 | 合肥市芯海电子科技有限公司 | A kind of input stage of the rail-to-rail mutual conductance amplifying circuit of reliable low pressure |
| CN111294001A (en) * | 2020-03-24 | 2020-06-16 | 中国科学院微电子研究所 | Rail-to-rail operational amplifier |
Non-Patent Citations (1)
| Title |
|---|
| 高瑜宏;李俊龙;: "一种低压恒跨导轨对轨CMOS运算放大器设计", 电子技术应用, no. 01, pages 54 - 57 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114123988B (en) | 2024-02-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101410696B1 (en) | Operational amplifier having high slew rate and stability, and operation method thereof | |
| US8513929B2 (en) | Method for providing and operating an LDO | |
| CN101453207B (en) | Operational amplifier | |
| EP0297639B1 (en) | Correction arrangement for an amplifier | |
| US9553548B2 (en) | Low drop out voltage regulator and method therefor | |
| JP5779490B2 (en) | Linear amplifier circuit | |
| US7619473B2 (en) | Fully-differential amplifier | |
| TW511281B (en) | A high performance intermediate stage circuit for a rail-to-rail input/output CMOS operational amplifier | |
| JP2000284843A (en) | Series regulator power source circuit | |
| US6590453B2 (en) | Folded cascode high voltage operational amplifier with class AB source follower output stage | |
| TW201012054A (en) | Rail-to-rail operational amplifier capable of reducing current consumption | |
| US20090115524A1 (en) | Output stage circuit and operational amplifier thereof | |
| CN114123988A (en) | Constant transconductance rail-to-rail input and output operational amplifier | |
| CN111294001B (en) | Rail-to-rail operational amplifier | |
| JP7420588B2 (en) | operational amplifier | |
| CN116126080B (en) | Source follower circuit and low dropout linear voltage regulator | |
| JPH0927721A (en) | Operational amplifyier device | |
| US9385658B2 (en) | Fast recovery scheme of transconductance gain for folded cascode amplifier | |
| CN115840483A (en) | Low dropout regulator with transient enhancement characteristic | |
| CN114448369A (en) | Amplifying circuit, related chip and electronic device | |
| JPH09116349A (en) | Operational amplifier | |
| CN111290461A (en) | Voltage regulator | |
| CN114094948B (en) | Rail-to-Rail Amplifier Common Mode Sensing Control Constant Transconductance Input Method | |
| TWI660259B (en) | Usb regulator with current buffer to reduce compensation capacitor size and provide for wide range of esr values of external capacitor | |
| CN112468101B (en) | Buffer with ultra-low static power consumption |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |