CN103296975B - Multiple Power Domain Operational Amplifier and Voltage Generator Using It - Google Patents

Abstract

A multi-power domain operational amplifier includes an input stage circuit, a power domain converting circuit and an active load. The input stage circuit is used for converting an input voltage into an input current in a first power domain. The power domain converting circuit is used for converting the set of input currents into a set of output currents in a second power domain. The active load is used for generating an output voltage according to the set of output currents, wherein a common range of the output voltage is shifted relative to a common range of the set of input voltages.

Description

Multiple Power Domain Operational Amplifier and Voltage Generator Using It

technical field

The invention relates to an operational amplifier with multiple power domains and a voltage generator using it.

Background technique

Due to the characteristics of semiconductor components, many applications require a set of positive and negative reference voltages that are not affected by temperature. The voltages are about +5 volts and -5 volts, which are close to the upper limit of the withstand voltage of medium-voltage components6 volt. The industry generally uses a bandgap reference circuit (bandgapreference circuit) to generate a zero temperature coefficient reference voltage of about 1.2 volts, and then uses this zero temperature coefficient reference voltage as a reference to perform step-up and step-down operations through a regulator, so that The reference voltage required by various applications can be generated.

Please refer to FIG. 1 , which shows a circuit diagram of an example of a conventional voltage generator. The voltage generator 10 includes a unity gain buffer 12 , a first voltage regulator 14 and a second voltage regulator 16 . In FIG. 1 , the operating voltage VDD is, for example, 3 volts, and the zero temperature coefficient reference voltage V _ref generated by the bandgap reference circuit is, for example, 1.2 volts. The zero temperature coefficient reference voltage V _ref can use the first voltage regulator 14 and the second voltage regulator 16 to perform step-up and step-down operations through the resistance relationship (R1+R2)/R1=5/1.2 to obtain a positive reference voltage V _OUTP =5V and negative reference voltage V _OUTN =-5V. Wherein, because the second regulator 16 takes the ground voltage 0 volts as a reference point, the power domain of its internal transconductance operational amplifier (operational transconductance amplifier, OTA) 18 needs to be VDD～-2VDD=3 volts～-6 volts, exceeding The withstand voltage of medium voltage components is limited and high voltage components must be used. As a result, poor device characteristics of high-voltage components will degrade overall circuit performance and occupy a large layout area.

Please refer to FIG. 2 , which shows a circuit diagram of another example of a conventional voltage generator. The voltage generator 20 includes a unity gain buffer 22 , a first voltage regulator 24 , a second voltage regulator 26 and a third voltage regulator 28 . In FIG. 2 , the operating voltage VDD is, for example, 3 volts, and the zero temperature coefficient reference voltage V _ref generated by the bandgap reference circuit is, for example, 1.2 volts. The zero temperature coefficient reference voltage V _ref is boosted by the first voltage regulator 24 through a resistance relationship to obtain a positive reference voltage V _OUTP =5 volts. In addition, the zero-temperature-coefficient reference voltage V _ref uses the second voltage regulator 26 to take the ground voltage of 0 volts as a reference point to perform a step-down operation to obtain -V _ref =-1.2 volts first, and then through the third voltage regulator 28 to perform a step-down operation. The negative reference voltage V _OUTN =-5 volts is obtained through the second step-down operation. Through the cascade two-stage voltage regulator structure 26 and 28, the power domain of the second voltage regulator 26 is VDD～-VDD=3 volts～-3 volts, and the power domain of the third voltage regulator 28 is GND～-2VDD=0 volts～-6 volts, all of which are maintained within the withstand voltage range of medium voltage components and avoid the use of high voltage components. However, in the structure of the voltage generator 20 , the multi-stage voltage regulator will cause the output voltage to be offset and affected by power noise.

In addition, the voltage generators 10 and 20 have to use the unity gain buffers 12 and 22 respectively to make the zero temperature coefficient reference voltage V _ref have a thrust to provide current output during the conversion from positive to negative voltage. However, the use of the unity-gain buffers 12 and 22 not only increases the circuit complexity and layout area, but also increases the offset of the output voltage and the impact of power supply noise.

Contents of the invention

The invention relates to an operational amplifier with multiple power domains and a voltage generator using it. Through the conversion of the power domains of the operational amplifier with multiple power domains, the voltage generator can generate the required positive reference voltage and negative reference voltage without using high-voltage components.

According to a first aspect of the present invention, an operational amplifier with multiple power domains is proposed, including an input stage circuit, a power domain conversion circuit and an active load. The input stage circuit is used for converting a set of input voltages into a set of input currents in a first power domain. The power domain conversion circuit is used for converting the set of input currents into a set of output currents in a second power domain. The active load is used to generate an output voltage according to the set of output currents, wherein a common-mode range of the output voltage is shifted relative to a common-mode range of the set of input voltages.

According to a second aspect of the present invention, a voltage generator is provided, including a series resistor, a first voltage regulator, and a second voltage regulator. The serial resistor has a first feedback terminal and a second feedback terminal. The first voltage regulator is used to output a first output voltage. The first voltage regulator includes a multi-power domain operational amplifier with a negative feedback configuration. The multi-power domain operational amplifier operates in a first power domain and a second power domain. The multi-power domain operational amplifier has an inverting input terminal receiving a first reference voltage, and a non-inverting input terminal coupled to the first feedback terminal. The second voltage regulator is used to output a second output voltage, the second voltage regulator includes a single power domain operational amplifier operating in a third power domain and having a negative feedback configuration, the single power domain operational amplifier has an inverting input terminal A second reference voltage is received, and a non-inverting input terminal is coupled to the second feedback terminal.

In order to have a better understanding of the above and other aspects of the present invention, an embodiment is exemplified below and described in detail in conjunction with the accompanying drawings.

Description of drawings

FIG. 1 shows a circuit diagram of an example of a conventional voltage generator.

FIG. 2 is a circuit diagram of another example of a conventional voltage generator.

FIG. 3 is a schematic diagram of a multi-power domain operational amplifier according to an embodiment.

FIG. 4 is a circuit diagram of a multi-power domain operational amplifier according to an embodiment.

FIG. 5 is a circuit diagram of a multi-power domain operational amplifier according to another embodiment.

FIG. 6 is a circuit diagram of a voltage generator according to an embodiment.

[Description of main component labels]

10, 20, 600: Voltage generator 12, 22: Unity gain buffer

14, 24, 610: first voltage regulator 16, 26, 620: second voltage regulator

18: Transconductance Operational Amplifier 28: Third Voltage Regulator

300, 400, 500, 615: Multiple Power Domain Operational Amplifiers

310, 410, 510: input stage circuits 320, 420, 520: power domain conversion circuits

422: the first set of current mirrors 424: the second set of current mirrors

522: the first group of stacking circuits 524: the second group of stacking circuits

330, 430, 530: Active load 625: Single supply domain operational amplifier

detailed description

The multi-power domain operational amplifier and the voltage generator using it proposed by the present invention adjust the common mode range (common mode range) of the multi-power domain operational amplifier through the conversion of the power domain, so that the voltage generator does not need to use high-voltage components The required positive reference voltage and negative reference voltage can be generated.

Please refer to FIG. 3 , which shows a schematic diagram of an operational amplifier with multiple power domains according to an embodiment. The multi-power domain operational amplifier 300 includes an input stage circuit 310 , a power domain conversion circuit 320 and an active load 330 . The input stage circuit 310 is coupled to a first voltage source VDD, which may be composed of a single PMOS input pair, a single NMOS input pair, or a PMOS input pair and an NMOS input pair. The input stage circuit 310 is used to convert a set of input voltages (V _in+ , V _in− ) into a set of input currents (I _in+ , I _in− ) in a first power domain. The first power domain is between the first voltage source and the second voltage source. In this example, the first voltage source is, for example, VDD, and the second voltage source is, for example, -VDD, that is, the first power domain is (VDD˜-VDD). Specifically, the first voltage source VDD is, for example, 3 volts, and the second voltage source -VDD is, for example, -3 volts.

The power domain conversion circuit 320 includes a first current buffer and a second current buffer. The first current buffer is coupled between the input stage circuit 310 and the second voltage source -VDD, and is used for converting the set of input currents (I _in+ , I _in- ) into a set of relay voltages in a relay power domain. flow. The first relay power domain is between the second voltage source and the third voltage source (such as GND). In this example, the first continuous power domain is (-VDD˜GND) for example. The second current buffer is coupled between the first current buffer and the third voltage source GND, and is used for generating a set of output currents (I _out+ , I _out− ) in a second power domain according to the set of relay currents. ). The second power domain is between the third voltage source and the fourth voltage source (eg -2VDD). In this example, the second power domain is, for example, (GND˜-2VDD) (more specifically, eg, 0V˜-6V).

The active load 330 can be constituted by a current mirror or a current source, which is coupled between the second current buffer and the fourth voltage source −2VDD, and is used to generate the output current (I _out+ , I _out− ) according to the set of output currents. An output voltage V _out . Wherein, a common-mode range (GND˜-2VDD) of the output voltage V _out is shifted relative to a common-mode range (VDD˜-VDD) of the set of input voltages (V _in+ , V _in− ).

Please refer to FIG. 4 , which shows a circuit diagram of an operational amplifier with multiple power domains according to an embodiment. The multi-power domain operational amplifier 400 includes an input stage circuit 410 , a power domain conversion circuit 420 and an active load 430 . The input stage circuit 410 may be formed by a PMOS input pair coupled to the first voltage source VDD. The input stage circuit 410 converts the input voltage (V _in+ , V _in− ) into an input current (I _in+ , I _in− ). In FIG. 4 , the power domain conversion circuit 420 is taken as an example for illustration. The current mirror architecture circuit 420 has a first set of current mirrors 422 and a second set of current mirrors 424 to realize the first current buffer and the second current buffer respectively.

The first group of current mirrors 422 is coupled between the input stage circuit 410 and the second voltage source -VDD, and is used for converting the input currents (I _in+ , I _in− ) into relay currents (I _re+ , I _re− ). The second set of current mirrors 424 is coupled between the first set of current mirrors 422 and the third voltage source GND, and is used to provide output currents (I _out+ , I _out− ) to active sources based on the third voltage source GND as a reference point. load 430 to generate the output voltage V _out . The active load 430 is coupled between the second set of current mirrors 424 and the fourth voltage source −2VDD. Since the common-mode range of the output voltage V _out shifts relative to the common-mode range of the input voltage (V _in+ , V _in- ), it is possible to output GND to -2VDD=0 without using high-voltage components. Voltage from volts to -6 volts.

Please refer to FIG. 5 , which shows a circuit diagram of an operational amplifier with multiple power domains according to another embodiment. The multi-power domain operational amplifier 500 includes an input stage circuit 510 , a power domain conversion circuit 520 and an active load 530 . The input stage circuit 510 is composed of a PMOS input pair coupled to the first voltage source VDD. The input stage circuit 510 converts the input voltage (V _in+ , V _in− ) into an input current (I _in+ , I _in− ). In FIG. 5 , the power domain conversion circuit 520 is taken as an example for illustration. The current mirror structure circuit 520 has a first set of folded-cascode 522 and a second set of folded-cascode 524 to realize the first current buffer and the second current buffer respectively.

The first stacking circuit 522 is coupled between the input stage circuit 510 and the second voltage source -VDD, and is used for converting the input current (I _in+ , I _in- ) into the relay current (I _re+ , I _re- ) . The second stacking circuit 524 is coupled between the first stacking circuit 522 and the third voltage source GND, and is used to provide output currents (I _out+ , I _out− ) to the third voltage source GND as a reference point. The active load 530 generates the output voltage V _out . The active load 530 is coupled between the second stacking circuit 524 and the fourth voltage source −2VDD. Since the common-mode range of the output voltage V _out shifts relative to the common-mode range of the input voltage (V _in+ , V _in- ), it is possible to output GND to -2VDD=0 without using high-voltage components. Voltage from volts to -6 volts. In addition, since the multi-power domain operational amplifier 500 receives and outputs current in a folded cascaded structure, it has better linear voltage regulation and noise immunity, and can provide a higher input common-mode range and output common-mode range.

In the above power domain conversion circuit 420/520, although only two current buffers are used as an example for illustration, it is not limited thereto. The power domain conversion circuit 420/520 may also include one or more third current buffers, Coupled between the first current buffer and the second current buffer, it is used to generate other one or more groups of relay currents according to the input current (I _in+ , I _in- ), and to generate other one or more groups of relay currents One group of currents is provided to the second current buffer, and the power domains of the other one or more groups of relay currents are different from each other.

Please refer to FIG. 6 , which shows a circuit diagram of a voltage generator according to an embodiment. The voltage generator 600 includes a series resistor R1 , a first voltage regulator 610 and a second voltage regulator 620 . The series resistor R1 has a first feedback terminal (node A) and a second feedback terminal (node B). The first regulator 610 is used to output a first output voltage V _OUTN . The first voltage regulator 610 includes a multiple power domain operational amplifier 615 with a negative feedback configuration, resistors R3 and R4 connected in series, and a transistor M1, wherein R3=R1 and R4=R2. The first end of the resistor R3 is coupled to the first feedback end (node A). The transistor M1 has a first terminal coupled to the voltage source −2VDD, a second terminal coupled to the second terminal of the resistor R4 , and a control terminal coupled to an output terminal of the multi-power domain operational amplifier 615 .

The actual circuit structure of the multi-power domain operational amplifier 615 can be shown as the aforementioned multi-power domain operational amplifier 300/400/500. The multi-power domain operational amplifier 615 is coupled between a first voltage source VDD and a second voltage source -VDD, and is coupled between a third voltage source GND and a fourth voltage source -2VDD. The multi-power domain operational amplifier 615 operates in a first power domain (VDD˜−VDD) and a second power domain (GND˜−2VDD). The multi-power-domain operational amplifier 615 has an inverting input end receiving a first reference voltage GND, and a non-inverting input end coupled to the first feedback end (node A). In this way, the first feedback terminal (node A) will be stable at the first reference voltage GND.

Since the first regulator 610 uses multiple power supply domains to operate the amplifier 615, it can use the first reference voltage GND as a reference point and generate voltages from GND～-2VDD=0 volts to -6 volts without using high-voltage components. output.

The second regulator 620 is used to output a second output voltage V _OUTP . The second voltage regulator 620 includes a single power domain operational amplifier 625 operating in a third power domain (2VDD˜GND) and having a negative feedback configuration, a resistor R2, and a transistor M2. The first end of the resistor R2 is coupled to the second feedback end (node B). The transistor M2 has a first terminal coupled to the voltage source 2VDD, a second terminal coupled to the second terminal of the resistor R2 , and a control terminal coupled to an output terminal of the single power domain operational amplifier 625 . The single power domain operational amplifier 625 is coupled between a fifth voltage source 2VDD and a third voltage source GND. The single power domain operational amplifier 625 has an inverting input terminal receiving a second reference voltage V _ref , and a noninverting input terminal coupled to the second feedback terminal (node B). In this way, the second feedback terminal (node B) is stable at the second reference voltage V _ref .

The second feedback terminal (node B) coupled to the second voltage regulator 620 provides the current required by the first feedback terminal (node A) coupled to the first voltage regulator 610, that is, the first voltage regulator 610 can be combined and a second voltage regulator 620 . In this way, through V _{feedback, B} = V _ref = 1.2 volts and V _{feedback, A} = GND = 0 volts, the resistor R1 generates the required DC current and flows through the resistors R2, R3 and R4 to obtain the first output voltage. V _OUTN =−5V and the second output voltage V _OUTP =5V.

The multi-power domain operational amplifier disclosed in the above embodiments of the present invention and the voltage generator using it can adjust the common-mode range of the multi-power domain operational amplifier through the conversion of the power domains of the multi-power domain operational amplifier, so that the voltage generator does not High voltage components are required, and the required positive and negative reference voltages can be generated with a small number of voltage regulators. In this way, not only the circuit design complexity is simplified and the layout area is reduced, but also the voltage offset caused by component mismatch and the power supply noise generated by the power transistor can be greatly reduced.

To sum up, although the present invention has been disclosed in a number of embodiments, they are not intended to limit the present invention. Those skilled in the art of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (27)

1. A multiple power domain operational amplifier comprising: an input stage circuit for converting a set of input voltages into a set of input currents in a first power domain; a power domain conversion circuit for converting the set of input currents into a set of output currents in a second power domain; and An active load for generating an output voltage according to the set of output currents, wherein a common-mode range of the output voltage is shifted relative to a common-mode range of the set of input voltages, the power domain conversion circuit includes a plurality of cascaded currents buffers, the power domains of the cascaded current buffers are different from each other. 2. The multi-power domain operational amplifier according to claim 1, wherein the concatenated current buffers of the power domain conversion circuit comprise: a first current buffer for converting the set of input currents into a set of first relay currents in a first relay power domain different from the first power domain; and A second current buffer is used for generating the set of output currents according to the set of first relay currents. 3. The multiple power domain operational amplifier according to claim 2, wherein the input stage circuit is coupled to a first voltage source, and the first current buffer is coupled between the input stage circuit and a second voltage source , the second current buffer is coupled between the first current buffer and a third voltage source, and the active load is coupled between the second current buffer and a fourth voltage source. 4. The multi-power domain operational amplifier according to claim 2, wherein the concatenated current buffers of the power domain conversion circuit further comprise: At least one third current buffer, coupled between the first current buffer and the second current buffer, is used to generate a second relay power domain according to the set of first relay currents At least one group of second relay currents, the second relay power domain is different from the first power domain and the first relay power domain, and one of the at least one group of second relay currents supplied to the second current buffer. 5. The multiple power domain operational amplifier as claimed in claim 1, wherein the input stage circuit converts the input voltage into the set of input currents using a PMOS input pair or an NMOS input pair. 6. The multiple power domain operational amplifier as claimed in claim 1, wherein the input stage circuit converts the input voltage into the set of input currents using a PMOS input pair and an NMOS input pair. 7. The multi-power domain operational amplifier as claimed in claim 1, wherein the power domain conversion circuit is a current mirror circuit. 8. The multiple power domain operational amplifier according to claim 7, wherein the input stage circuit is coupled to a first voltage source, the current mirror structure circuit has a first set of current mirrors coupled to the input stage circuit and a Between the second voltage source, a second group of current mirrors is coupled between the first group of current mirrors and a third voltage source, and the active load is coupled between the second group of current mirrors and a fourth voltage source between sources. 9. The multi-power domain operational amplifier as claimed in claim 1, wherein the power domain conversion circuit is a folded stack circuit. 10. The multiple power domain operational amplifier of claim 9, wherein the input stage circuit is coupled to a first voltage source, the folded stack circuit has a first set of stack circuits coupled to the input Between the stage circuit and a second voltage source, and a second stacking circuit coupled between the first stacking circuit and a third voltage source, the active load is coupled to the second stacking circuit connected between the circuit and a fourth voltage source. 11. The multiple power domain operational amplifier as claimed in claim 1, wherein the active load is constituted by a current mirror or a current source. 12. A voltage generator comprising: A series resistor with a first feedback terminal and a second feedback terminal; A first voltage regulator for outputting a first output voltage, the first voltage regulator includes a multiple power domain operational amplifier with a negative feedback configuration, the multiple power domain operational amplifier operates in a first power domain with In a second power domain, the multi-power domain operational amplifier has an inverting input terminal receiving a first reference voltage, and a non-inverting input terminal coupled to the first feedback terminal, and the multiple power domain operational amplifier includes a plurality of stacked connected current buffers, the power domains of each of the connected current buffers are different from each other; and A second regulator for outputting a second output voltage, the second regulator comprising a single power domain operational amplifier operating in a third power domain and having a negative feedback configuration, the single power domain operational amplifier having An inverting input terminal receives a second reference voltage, and a non-inverting input terminal is coupled to the second feedback terminal. 13. The voltage generator according to claim 12, wherein the multiple power domain operational amplifier is coupled between a first voltage source and a second voltage source, and is coupled between a third voltage source and a fourth voltage source Between the voltage sources, the single power domain operational amplifier is coupled between a fifth voltage source and the third voltage source. 14. The voltage generator according to claim 12, wherein the first feedback terminal and the second feedback terminal are respectively stable at the first reference voltage and the second reference voltage. 15. The voltage generator according to claim 12, wherein the first voltage regulator further comprises: At least one resistor connected in series has a first end and a second end, the first end is connected in series with the first feedback end; and A transistor has a first terminal coupled to a voltage source, a second terminal coupled to the second terminal of the at least one resistor, and a control terminal coupled to an output terminal of the multi-power domain operational amplifier. 16. The voltage generator according to claim 12, wherein the second voltage regulator further comprises: At least one resistor connected in series has a first end and a second end, the first end is connected in series with the second feedback end; and A transistor has a first terminal coupled to a voltage source, a second terminal coupled to the second terminal of the at least one resistor, and a control terminal coupled to an output terminal of the single power domain operational amplifier. 17. The voltage generator according to claim 12, wherein the multiple power domain operational amplifier comprises: An input stage circuit, including a group of input terminals as the non-inverting input terminal and the inverting input terminal of the multi-power domain operational amplifier, and according to a group of input voltages received by the group of input terminals, generates the first A set of input currents within the power domain; a power domain conversion circuit for converting the set of input currents into a set of output currents in the second power domain; and An active load is used to generate a third output voltage according to the set of output currents, wherein a common mode range of the third output voltage is shifted relative to a common mode range of the set of input voltages, and the power domain conversion circuit includes the cascade current buffers. 18. The voltage generator according to claim 17, wherein the concatenated current buffers of the power domain conversion circuit comprise: a first current buffer for converting the set of input currents into a set of first relay currents in a first relay power domain different from the first power domain; and A second current buffer is used for generating the set of output currents according to the set of first relay currents. 19. The voltage generator according to claim 18, wherein the input stage circuit is coupled to a first voltage source, the first current buffer is coupled between the input stage circuit and a second voltage source, the The second current buffer is coupled between the first current buffer and a third voltage source, and the active load is coupled between the second current buffer and a fourth voltage source. 20. The voltage generator according to claim 18, wherein the concatenated current buffers of the power domain conversion circuit further comprise: At least one third current buffer, coupled between the first current buffer and the second current buffer, is used to generate a second relay power domain according to the set of first relay currents At least one group of second relay currents, the second relay power domain is different from the first power domain and the first relay power domain, and one of the at least one group of second relay currents supplied to the second current buffer. 21. The voltage generator according to claim 17, wherein the input stage circuit converts the input voltage into the set of input currents using a PMOS input pair or an NMOS input pair. 22. The voltage generator of claim 17, wherein the input stage circuit converts the input voltage into the set of input currents using a PMOS input pair and an NMOS input pair. 23. The voltage generator according to claim 17, wherein the power domain conversion circuit is a current mirror circuit. 24. The voltage generator according to claim 23, wherein the input stage circuit is coupled to a first voltage source, the current mirror structure circuit has a first set of current mirrors coupled to the input stage circuit and a second Between the voltage sources, a second group of current mirrors is coupled between the first group of current mirrors and a third voltage source, and the active load is coupled between the second group of current mirrors and a fourth voltage source between. 25. The voltage generator according to claim 17, wherein the power domain conversion circuit is a folded stack circuit. 26. The voltage generator according to claim 25, wherein the input stage circuit is coupled to a first voltage source, the folded stack circuit has a first set of stack circuits coupled to the input stage circuit Between a second voltage source and a second stacking circuit coupled between the first stacking circuit and a third voltage source, the active load is coupled to the second stacking circuit and a fourth voltage source. 27. The voltage generator of claim 17, wherein the active load is constituted by a current mirror or a current source.