Cascade LDO voltage stabilizer
阅读说明:本技术 级联ldo稳压器 (Cascade LDO voltage stabilizer ) 是由 杜定坤 J·B·弗莱彻 于 2018-05-23 设计创作,主要内容包括:公开了一种稳压器。该稳压器为级联的,包括第一级和第二级。第一级可以是包括由第一PMOS晶体管实现的源极跟随器的无电容器的第一级,其中第一PMOS晶体管在其相应栅极端子上接收第一参考电压。第一级被耦接以接收来自外部电压源的第一电压,并向第二级提供第二电压。第二级可直接且唯一地耦接到第一级,其中耦接到第一级输出的一个不具有电容器或连接。第二级可在输出节点上提供输出电压,其中输出电压小于第二电压。(A voltage regulator is disclosed. The voltage regulator is cascaded and comprises a first stage and a second stage. The first stage may be a capacitor-less first stage including a source follower implemented by a first PMOS transistor, wherein the first PMOS transistor receives a first reference voltage on its respective gate terminal. The first stage is coupled to receive a first voltage from an external voltage source and to provide a second voltage to the second stage. The second stage may be directly and exclusively coupled to the first stage, with one coupled to the first stage output having no capacitors or connections. The second stage may provide an output voltage on the output node, where the output voltage is less than the second voltage.)
1. A circuit, comprising:
a voltage regulator, wherein the voltage regulator comprises:
a first stage, wherein the first stage is a capacitor-less first stage and includes a source follower implemented using a first P-type metal oxide semiconductor (PMOS) transistor, wherein a gate terminal of the first PMOS transistor is coupled to receive a first reference voltage, wherein the first stage is coupled to receive a first voltage from an external voltage source and is configured to output a second voltage less than the first voltage on an intermediate node; and
a second stage coupled to receive the second voltage from the first stage, wherein the first stage is configured to provide the second voltage directly and exclusively to the second stage via the intermediate node, wherein the second stage is configured to output a third voltage to a load circuit on an output node.
2. The circuit of claim 1, wherein the first stage further comprises a common-source amplifier implemented using a second PMOS transistor, wherein the first PMOS transistor comprises a load on the common-source amplifier.
3. The circuit of claim 2, further comprising a common-gate amplifier implemented using NMOS transistors coupled to both the first PMOS transistor and the second PMOS transistor, wherein the common-gate amplifier is configured to drive a voltage substantially equal to the second voltage to a gate terminal of the second PMOS transistor.
4. The circuit of claim 2, wherein the second stage comprises an amplifier having an inverting input and a non-inverting input, wherein the non-inverting input of the amplifier is coupled to receive a second reference voltage, and wherein amplifier comprises a supply voltage input coupled to receive the second voltage.
5. The circuit of claim 4, wherein an output of the amplifier is coupled to a gate terminal of an NMOS transistor.
6. The circuit of claim 5, further comprising a current mirror coupled to the drain terminal of the NMOS transistor, the current mirror comprising a third PMOS transistor and a fourth PMOS transistor, wherein respective gate terminals of the third PMOS transistor and the fourth PMOS transistor are coupled to the drain terminal of the NMOS transistor, and wherein a source terminal of the fourth PMOS transistor is coupled to the output node.
7. The circuit of claim 4, further comprising a voltage divider coupled between the output node and a reference node, wherein the amplifier is coupled to receive a divided voltage from the voltage divider on its inverting input.
8. The circuit of claim 1, wherein the first stage comprises a first series regulator, and wherein the second stage comprises a second series regulator.
9. A method, the method comprising:
receiving a first voltage at a first stage of a voltage regulator;
providing a second voltage from the first stage that is less than the first voltage, wherein the first stage is capacitor-less and includes a source follower implemented using a first P-type metal oxide semiconductor (PMOS) transistor and a common source amplifier implemented using a second PMOS transistor;
receiving the second voltage at a second stage of the voltage regulator, wherein the first stage is coupled to provide the second voltage directly and exclusively to the second stage via an intermediate node; and
providing a third voltage on an output node of the second stage of the voltage regulator, the third voltage being less than the second voltage.
10. The method of claim 9, further comprising the source follower acting as a load on the common-source amplifier.
11. The method of claim 9, further comprising a common-gate amplifier coupled to the source follower and the common-source amplifier, wherein common-gate amplifier is implemented using a first NMOS transistor, and wherein the common-gate amplifier is configured to drive a voltage substantially equal to the second voltage to a gate terminal of the second PMOS transistor.
12. The method of claim 11, further comprising:
providing a first reference voltage to a gate terminal of the first PMOS transistor; and
providing a bias voltage to a gate terminal of the first NMOS transistor.
13. The method of claim 12, further comprising:
providing the second voltage to a supply voltage input of an amplifier in the second stage, the amplifier having an inverting input and a non-inverting input;
providing a second reference voltage to the non-inverting input of the amplifier;
the amplifier drives an output voltage onto a gate terminal of a second NMOS transistor.
14. The method of claim 13, further comprising:
the second NMOS transistor provides a current source to a current mirror circuit, the current mirror circuit comprising a third PMOS transistor and a fourth PMOS transistor;
outputting the third voltage on the output node, the output node coupled to a drain terminal of the fourth PMOS transistor; and
providing a divided voltage to the inverting input of the amplifier from a voltage divider coupled to the output node.
15. A voltage regulator, comprising:
a first stage, wherein the first stage comprises a source follower implemented using a first P-type metal-oxide-semiconductor (PMOS) transistor and a common-source amplifier implemented using a second PMOS transistor, wherein the first PMOS transistor and the second PMOS transistor are each coupled to an intermediate node, wherein the first stage is a capacitor-less first stage; and
a second stage, wherein the first stage is configured to provide an intermediate voltage directly and exclusively to the second stage via the intermediate node, wherein the second stage is configured to provide an output voltage to a load circuit on an output node.
16. The voltage regulator of claim 15, wherein the first stage is coupled to receive a supply voltage from a voltage source external to the voltage regulator, wherein the second stage is configured to receive the intermediate voltage at the intermediate node, the intermediate voltage having a value less than the supply voltage, and wherein the second stage is configured to provide the output voltage having a value less than the intermediate voltage.
17. The voltage regulator of claim 15, wherein the first stage further comprises a common-gate amplifier coupled to drive a voltage having substantially the same value as the intermediate voltage to the gate terminal of the second PMOS transistor.
18. The voltage regulator of claim 15, wherein the second stage comprises an operational amplifier having a supply voltage input coupled to receive the intermediate voltage from the intermediate node.
19. The voltage regulator of claim 15, wherein the second stage comprises a current mirror circuit comprising a third PMOS transistor and a fourth PMOS transistor, wherein each of the third PMOS transistor and the fourth PMOS transistor has a respective source terminal coupled to the intermediate node, and wherein a drain terminal of the fourth PMOS transistor is coupled to the output node.
20. The voltage regulator of claim 15, wherein the voltage regulator implements a Low Dropout (LDO) voltage regulator, wherein the first stage comprises a first series regulator and the second stage comprises a second series regulator.
Technical Field
The present disclosure relates to electronic circuits, and more particularly to voltage regulator circuits.
Background
Voltage regulators are commonly used in a variety of circuits to provide a desired voltage to a particular circuit. To this end, a variety of voltage regulator circuits are available to meet various applications. Linear voltage regulators are used in many different applications where the available supply voltage exceeds a suitable value for the circuit to be supplied. Thus, the linear regulator may output a voltage less than the received supply voltage.
Some linear regulators may be implemented in stages. Each stage may facilitate generation of an output voltage based on a provided input voltage (e.g., from an external source). The stages may be coupled to each other with a capacitor coupled to the output of each stage. These capacitors can stabilize the voltage output by each stage. In a voltage regulator implemented on an Integrated Circuit (IC), the output of a given regulator stage may have external connections for coupling to capacitors implemented external to the IC (e.g., on a printed circuit board or PCB).
Disclosure of Invention
A voltage regulator is disclosed. In one embodiment, the voltage regulator is cascaded and includes a first stage and a second stage. The first stage may be a capacitor-less first stage including a source follower implemented by a first P-type metal oxide semiconductor (PMOS) transistor, wherein the first PMOS transistor receives a first reference voltage on its respective gate terminal. The first stage is coupled to receive a first voltage from an external voltage source and to provide a second voltage to the second stage. The second stage may be directly and exclusively coupled to the first stage through an intermediate node through which the second voltage is output, wherein the one coupled to the first stage output has no capacitor or connection. The second stage may provide an output voltage on the output node, where the output voltage is less than the second voltage.
In one embodiment, the first stage includes a common source amplifier implemented using PMOS transistors in addition to PMOS based source followers. The first stage may also include a common-gate amplifier coupled to drive a voltage substantially equal to the second voltage to a gate terminal of a PMOS transistor implementing a common-source amplifier. The common-source amplifier and the source follower are both coupled to an intermediate node.
In various embodiments, the second stage may include an operational amplifier configured to drive the gate of the transistor and a current mirror implemented using PMOS transistors. The current mirror may mirror the current consumed by the transistor coupled to the amplifier output. The second stage may output an output voltage on the output node that is less than the second voltage.
Each stage may help provide a portion of the overall Power Supply Rejection Ratio (PSRR) for the voltage regulator. The first stage may be more loosely regulated than the second stage.
Drawings
The following detailed description makes reference to the accompanying drawings, which are now briefly described.
FIG. 1 is a block diagram of one embodiment of an Integrated Circuit (IC) including a voltage regulator and a functional circuit block.
Fig. 2 is a schematic diagram of one embodiment of a voltage regulator.
FIG. 3 is a flow chart illustrating one embodiment of a method for operating a voltage regulator.
FIG. 4 is a block diagram of one embodiment of an exemplary system.
While the embodiments disclosed herein are susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the scope of the claims to the particular form disclosed. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure of the present application as defined by the appended claims.
The present disclosure includes references to "one embodiment," a particular embodiment, "" some embodiments, "" various embodiments, "or" an embodiment. The appearances of the phrases "in one embodiment," "in a particular embodiment," "in some embodiments," "in various embodiments," or "in an embodiment" are not necessarily referring to the same embodiment. The particular features, structures, or characteristics may be combined in any suitable manner consistent with the present disclosure.
Within this disclosure, different entities (which may be referred to variously as "units," "circuits," other components, etc.) may be described or claimed as "configured to" perform one or more tasks or operations. This expression-an [ entity ] configured to [ perform one or more tasks ] -is used herein to refer to a structure (i.e., a physical thing, such as an electronic circuit). More specifically, this expression is used to indicate that the structure is arranged to perform one or more tasks during operation. A structure may be said to be "configured to" perform a task even though the structure is not currently being operated on. "an integral distribution circuit configured to distribute integrals to multiple processor cores" is intended to cover, for example, an integrated circuit having circuitry that performs this function during operation, even if the integrated circuit concerned is not currently being used (e.g., a power supply is not connected to it). Thus, an entity described or stated as "configured to" perform a task refers to physical things such as devices, circuits, memories storing executable program instructions, etc. that are used to perform the task. This phrase is not used herein to refer to intangible matter.
The term "configured to" is not intended to mean "configurable to". For example, an unprogrammed FPGA would not be considered "configured to" perform a particular function, although it may be "configurable" to perform that function after programming.
The expression in the appended claims that an architecture "configured to" perform one or more tasks is expressly intended to refer to that claim elementIs not limited toReference 35 u.s.c. § 112 (f). Thus, no claim in the filed application is intended to be construed as having a device-plus-function element. If the applicant wanted to refer to segment 112(f) during the application process, it would use "for" [ perform function]"means" structures are used to describe claim elements.
As used herein, the term "based on" is used to describe one or more factors that affect the determination. This term does not exclude that there may be additional factors that may influence the determination. That is, the determination may be based on specified factors only or on specified factors and other unspecified factors. Consider the phrase "determine a based on B. This phrase specifies that B is a factor used to determine a or that B affects a determination. This phrase does not exclude that the determination of a may also be based on some other factor such as C. This phrase is also intended to cover embodiments in which a is determined based on B only. As used herein, the phrase "based on" is synonymous with the phrase "based, at least in part, on".
As used herein, the phrase "responsive to" describes one or more factors that trigger an effect. The phrase does not exclude the possibility that other factors may affect or otherwise trigger an effect. That is, the effect may be responsive to only these factors, or may be responsive to specified factors as well as other unspecified factors. Consider the phrase "perform a in response to B. The phrase specifies that B is the factor that triggers the performance of a. The phrase does not exclude that performing a may also be responsive to some other factor, such as C. The phrase is also intended to encompass embodiments in which a is performed only in response to B.
As used herein, the terms "first," "second," and the like, serve as labels for terms following them, and do not imply any type of ordering (e.g., spatial, temporal, logical, etc.), unless otherwise specified. For example, in a register file having eight registers, the terms "first register" and "second register" may be used to refer to any two of the eight registers, rather than, for example, only logical registers 0 and 1.
The term "or" as used in the claims is used as an inclusive or, rather than an exclusive or. For example, the phrase "at least one of x, y, or z" means any of x, y, and z, and any combination thereof.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. However, it will be recognized by one of ordinary skill in the art that aspects of the disclosed embodiments may be practiced without these specific details. In some instances, well-known circuits, structures, signals, computer program instructions, and techniques have not been shown in detail in order not to obscure the disclosed embodiments.
Detailed Description
Turning now to fig. 1, a simplified block diagram of one embodiment of an Integrated Circuit (IC) is shown. It should be noted that this simplified embodiment is shown for illustrative purposes, and is not intended to be limiting. Furthermore, other types of circuits (e.g., power management circuits) may also be implemented on IC 10 and may be coupled to and interact with the circuits/units illustrated herein.
IC 10 in the illustrated embodiment includes a
In the illustrated embodiment,
As discussed further below,
Fig. 2 is a schematic diagram of one embodiment of
The first stage ("stage 1") of
In addition to the above, the first stage of
During operation, MP2 acts as the previously mentioned common source amplifier with MP1 as its load. The gate terminal of MP2 is partially driven by MN1, to which its drain terminal is coupled. More specifically, MP1 and MN1 can effectively transfer the voltage Vdd _ Mid on the intermediate node to the gate terminal of MP 2. MP1 may effectively convert a reference voltage received on its gate terminal (VRef1) to an intermediate voltage Vdd _ Mid, which voltage (or substantially equal value) is driven to the gate terminal of MP 2. Thus, MP1 and MP2 both work in concert to drive Vdd _ Mid at the intermediate node. In addition, the first stage of
The use of PMOS transistors as shown in the first stage, as opposed to NMOS transistors, may provide significant advantages. For example, the use of PMOS transistors in the source follower and in the common-source amplifier may make it easier to meet voltage headroom requirements (e.g., due to the gate and drain voltages required for PMOS devices). Furthermore, the unique combination of a PMOS-based common-source amplifier and a PMOS-based source follower may allow the circuit to more efficiently regulate the intermediate voltage (e.g., Vdd _ Mid as shown in fig. 2).
The second stage of
The output of amplifier a1 is coupled to the gate terminal of NMOS transistor MN 2. The transistor MN2 can consume current by a current mirror implemented with PMOS transistors MP3 and MP 4. Transistor MP3 is diode coupled between the intermediate node and the drain terminal of MN 2. The current is mirrored by MP4 through MP3 and MN2, the source-drain path of which is coupled between the intermediate node and an output node ('Out') at which the output voltage VLDO of
The output voltage from the
As described above, each stage of
FIG. 3 is a flow chart illustrating one embodiment of a method for operating a voltage regulator.
The first stage may generate an intermediate voltage using a PMOS based source follower and a PMOS based common-source amplifier implemented therein (block 310). The first stage of the regulator may include an arrangement of PMOS devices as shown in fig. 2 to generate an intermediate voltage at an intermediate node coupled between the two devices (and to the second stage). The intermediate voltage may be less than a voltage provided to the first stage from an external source. Furthermore, the intermediate node may be coupled only between the first stage and the second stage, without connection to the capacitor (internal or external to the circuit) provided by that node.
The second stage may receive the intermediate voltage and generate an output voltage of the regulator circuit (block 315). In one embodiment, the second stage may include a PMOS based current mirror, such as shown in fig. 2. However, other second level embodiments are possible and contemplated. The output voltage provided by the second stage may be less than the intermediate voltage received thereby.
Turning next to fig. 4, a block diagram of one embodiment of a
The
Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.
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