Amplifier circuit

Abstract

An amplifier circuit includes a multi-stage amplifier, a first feedback circuit, and a second feedback circuit. The multi-stage amplifier includes a first-stage amplifier, a last-stage amplifier, and at least one intermediate-stage amplifier cascaded between the first-stage amplifier and the last-stage amplifier. The first feedback circuit is used to couple the positive output terminal of the last-stage amplifier back to the positive input terminal of the at least one intermediate-stage amplifier, or to couple the negative output terminal of the last-stage amplifier back to the negative input terminal of the at least one intermediate-stage amplifier. The second feedback circuit is used to couple the positive output terminal of the last-stage amplifier back to the positive input terminal of the last-stage amplifier, or to couple the negative output terminal of the last-stage amplifier back to the negative input terminal of the last-stage amplifier.

Description

Technical Field

[0001] This application for invention relates to an amplifier circuit, particularly an amplifier circuit with a compensation circuit. Background Art

[0002] Generally speaking, a traditional operational amplifier is usually a two-stage amplifier circuit, and often separates the first pole and the second pole through Miller compensation to improve the phase. On the other hand, it may cause a reduction in the gain bandwidth product or the 3dB bandwidth. Summary of the Invention

[0003] In view of this, this application for invention provides an amplifier circuit. The amplifier circuit includes a multi-stage amplifier, a first feedback circuit, and a second feedback circuit. The multi-stage amplifier includes a first-stage amplifier, a last-stage amplifier, and at least one intermediate-stage amplifier cascaded between the first-stage amplifier and the last-stage amplifier. The first feedback circuit is used to couple the positive output terminal of the last-stage amplifier back to the positive input terminal of the at least one intermediate-stage amplifier, or to couple the negative output terminal of the last-stage amplifier back to the negative input terminal of the at least one intermediate-stage amplifier. The second feedback circuit is used to couple the positive output terminal of the last-stage amplifier back to the positive input terminal of the last-stage amplifier, or to couple the negative output terminal of the last-stage amplifier back to the negative input terminal of the last-stage amplifier.

[0004] This application for invention also provides another amplifier circuit. The amplifier circuit includes a multi-stage amplifier, a negative feedback circuit, and a positive feedback circuit. The multi-stage amplifier includes a first-stage amplifier, a last-stage amplifier, and at least one intermediate-stage amplifier cascaded between the first-stage amplifier and the last-stage amplifier. The negative feedback circuit is coupled to the output terminal of the last-stage amplifier and is used to provide negative feedback to the input terminal of the at least one intermediate-stage amplifier and the input terminal of the last-stage amplifier. The positive feedback circuit is coupled to the output terminal of the last-stage amplifier and is used to provide positive feedback to the input terminal of the at least one intermediate-stage amplifier.

[0005] Through the above positive feedback circuit design, the amplifier circuit of this application for invention can increase the 3dB bandwidth without affecting the unity gain frequency. In addition, through the above multi-stage amplifier design, the amplifier circuit of this application for invention can increase the gain. Description of the Drawings

[0006] Figure 1 A schematic diagram of an amplifier circuit is shown according to some embodiments of this application for invention.

[0007] Figure 2 FIG2 is a schematic diagram illustrating an amplifier circuit according to other embodiments of the present application.

[0008] Explanation of symbols

[0009] 100, 200: Amplifier circuit

[0010] 102, 202: Multi-stage amplifier

[0011] 112, 212: First stage amplifier

[0012] 114, 214: Intermediate amplifier

[0013] 116, 216: Final amplifier

[0014] R f1P 、R f1N 、R fP 、R fN : The first compensation resistor

[0015] R f2P 、R f2N : Second compensation resistor

[0016] R m1P 、R m1N 、R mP 、R mN : The third compensation resistor

[0017] R m2P 、R m2N : The fourth compensation resistor

[0018] C f1P 、C f1N : The first compensation capacitor

[0019] C f2P 、C f2N : Second compensation capacitor

[0020] C m1P 、C m1N : The third compensation capacitor

[0021] C m2P 、C m2N : The fourth compensation capacitor

[0022] V IP 、V 2IP 、V 3IP : Positive input terminal

[0023] V IN 、V 2IN 、V 3IN : Negative input terminal

[0024] V OP and V 3OP : Positive output terminal

[0025] V ON and V 3ON : Negative output terminal Detailed implementation manners

[0026] The following is a detailed description with reference to the accompanying drawings by way of example. However, the specific embodiments described are only used to explain the present invention and do not limit the present invention. The description of the structure and operation is not used to limit the order of its execution. Any structure recombined by components that produces an apparatus with equivalent functions is within the scope covered by this application of the present invention.

[0027] In the terms used in this specification and claims of the present disclosure, unless otherwise specified, they generally have the common meaning in this field for each term, as well as the common meaning in the disclosed content and in the specific content.

[0028] Regarding the "first", "second", etc. used herein, they do not particularly refer to the meaning of order or sequence, nor are they used to limit this disclosure. They are merely used to distinguish components or operations described with the same technical terms.

[0029] In addition, regarding the "coupled" or "connected" used herein, it can refer to two or more components directly making physical or electrical contact with each other, or indirectly making physical or electrical contact with each other, and can also refer to two or more components operating or acting on each other.

[0030] Please refer to Figure 1 , one embodiment of this application of the present invention is about an amplifier circuit 100. The amplifier circuit 100 includes a multi-stage amplifier 102, a negative feedback circuit, and a positive feedback circuit. Among them, the multi-stage amplifier 102 includes a first-stage amplifier 112, a last-stage amplifier 116, and at least one intermediate-stage amplifier 114 cascaded between the first-stage amplifier 112 and the last-stage amplifier 116.

[0031] In this embodiment, the first-stage amplifier 112, the intermediate-stage amplifier 114, and the last-stage amplifier 116 are all differential amplifiers. That is to say, the first amplifier 112 includes a positive input terminal (equivalent to the positive input terminal V of the multi-stage amplifier 102 IP ), a negative input terminal (equivalent to the negative input terminal V of the multi-stage amplifier 102 IN ), a positive output terminal, and a negative output terminal. The intermediate-stage amplifier 114 and the last-stage amplifier 116 each also include a similar structure, so they will not be described in detail here.

[0032] Structurally, the positive feedback circuit is coupled to the output end of the last-stage amplifier 116 and is used to provide positive feedback to one input end of the intermediate-stage amplifier 114 and one input end of the last-stage amplifier 116. In this embodiment, the positive feedback circuit includes a first feedback circuit and a second feedback circuit.

[0033] Specifically, the first feedback circuit includes first compensation resistors R f1P 、R f1N and first compensation capacitors C f1P 、C f1N . The first feedback circuit is used to couple the positive output terminal V 3OP (equivalent to the negative output terminal V ON ) of the last-stage amplifier 116 back to the positive input terminal V 2IP of the intermediate-stage amplifier 114, and is used to couple the negative output terminal V 3ON (equivalent to the positive output terminal V OP ) of the last-stage amplifier 116 back to the negative input terminal V 2IN of the intermediate-stage amplifier 114.

[0034] As Figure 1 shown, the first compensation resistor R f1P is coupled to the first compensation capacitor C f1P and the positive output terminal V 3OP of the last-stage amplifier 116, while the first compensation capacitor C f1P is coupled to the first compensation resistor R f1P and the positive input terminal V 2IP of the intermediate-stage amplifier 114. The first compensation resistor R f1N is coupled to the first compensation capacitor C f1N and the negative output terminal V 3ON of the last-stage amplifier 116, while the first compensation capacitor C f1N is coupled to the first compensation resistor R f1N and the negative input terminal V 2IN of the intermediate-stage amplifier 114.

[0035] The second feedback circuit includes second compensation resistors R f2P 、R f2N and second compensation capacitors C f2P 、C f2N . The second feedback circuit is used to couple the positive output terminal V 3OP of the last-stage amplifier 116 back to the positive input terminal V 3IP of the last-stage amplifier 116, and is used to couple the negative output terminal V 3ON of the last-stage amplifier 116 back to the negative input terminal V 3IN of the last-stage amplifier 116.

[0036] For another example Figure 1 As shown, the second compensation resistor R f2P is coupled to the second compensation capacitor C f2P and the positive output terminal V 3OP of the last-stage amplifier 116, and the second compensation capacitor C f2P is coupled to the second compensation resistor R f2P and the positive input terminal V 3IP of the last-stage amplifier 116. The second compensation resistor R f2N is coupled to the second compensation capacitor C f2N and the negative output terminal V 3ON of the last-stage amplifier 116, and the second compensation capacitor C f2N is coupled to the second compensation resistor R f2N and the negative input terminal V 3IN .

[0037] The negative feedback circuit is coupled to one of the output terminals of the last-stage amplifier 116 and is used to provide negative feedback to one of the input terminals of the intermediate-stage amplifier 114 and one of the input terminals of the last-stage amplifier 116. In this embodiment, the negative feedback circuit includes a third feedback circuit and a fourth feedback circuit.

[0038] Specifically, the third feedback circuit includes third compensation resistors R m1P , R m1N and third compensation capacitors C m1P , C m1N . The third feedback circuit is used to couple the positive output terminal V 3OP of the last-stage amplifier 116 back to the negative input terminal V 2IN of the intermediate-stage amplifier 114, and is used to couple the negative output terminal V 3ON of the last-stage amplifier 116 back to the positive input terminal V 2IP of the intermediate-stage amplifier 114.

[0039] As Figure 1 shown, the third compensation resistor R m1P is coupled to the third compensation capacitor C m1P and the positive output terminal V 3OP of the last-stage amplifier 116, and the third compensation capacitor C m1P is coupled to the third compensation resistor R m1P and the negative input terminal V 2IN of the intermediate-stage amplifier 114. The third compensation resistor R m1N is coupled to the third compensation capacitor C m1N and the negative output terminal V 3ON of the last-stage amplifier 116, and the third compensation capacitor C m1NCoupled to the third compensation resistor R m1N and the positive input terminal V of the intermediate-stage amplifier 114 2IP .

[0040] The fourth feedback circuit includes fourth compensation resistors R m2P , R m2N and fourth compensation capacitors C m2P , C m2N . The fourth feedback circuit is used to couple the positive output terminal V of the final-stage amplifier 116 3OP back to the negative input terminal V of the final-stage amplifier 116 3IN , and is used to couple the negative output terminal V of the final-stage amplifier 116 3ON back to the positive input terminal V of the final-stage amplifier 116 3IP .

[0041] For another example Figure 1 as shown, the fourth compensation resistor R m2P is coupled to the fourth compensation capacitor C m2P and the positive output terminal V of the final-stage amplifier 116 3OP , while the fourth compensation capacitor C m2P is coupled to the fourth compensation resistor R m2P and the negative input terminal V of the final-stage amplifier 116 3IN . The fourth compensation resistor R m2N is coupled to the fourth compensation capacitor C m2N and the negative output terminal V of the final-stage amplifier 116 3ON , while the fourth compensation capacitor C f2N is coupled to the fourth compensation resistor R f2N and the positive input terminal V of the final-stage amplifier 116 3IP .

[0042] It can be understood that when the number of intermediate-stage amplifiers 114 is more than two, the positive feedback circuit can be used to provide positive feedback to one of the input terminals of each intermediate-stage amplifier 114 and one of the input terminals of the final-stage amplifier 116.

[0043] In other partial embodiments, the compensation capacitor (for example: the first compensation capacitor C f1P ) and the compensation resistor (for example: the first compensation resistor R f1P ) can be interchanged. In other words, the first compensation capacitor C f1P is coupled to the first compensation resistor R f1P and the positive output terminal V of the final-stage amplifier 116 3OP , while the first compensation resistor R f1P is coupled to the first compensation capacitor C f1P and the positive input terminal V of the intermediate-stage amplifier 114 2IPThe settings of the remaining compensation capacitors and compensation resistors are similar to those of the first compensation capacitor C f1P and the first compensation resistor R f1P , so they will not be elaborated here.

[0044] In other partial embodiments, the positive feedback circuit and the negative feedback circuit may only include three of the first feedback circuit, the second feedback circuit, the third feedback circuit, and the fourth feedback circuit. For example, as Figure 1 shown, the second feedback circuit (including the second compensation resistors R f2P , R f2N and the second compensation capacitors C f2P , C f2N ) may not exist.

[0045] Please refer to Figure 2 , another embodiment of the present invention application is about an amplifier circuit 200. The amplifier circuit 200 includes a multi-stage amplifier 202, a negative feedback circuit, and a positive feedback circuit. Among them, the multi-stage amplifier 202 includes a first-stage amplifier 212, a last-stage amplifier 216, and at least one intermediate-stage amplifier 214 cascaded between the first-stage amplifier 212 and the last-stage amplifier 216. In this embodiment, the settings similar to those of the amplifier circuit 100 in the amplifier circuit 200 will not be elaborated.

[0046] Structurally, the positive feedback circuit includes a first feedback circuit and a second feedback circuit. Specifically, the first feedback circuit includes the first compensation resistors R fP , R fN and the first compensation capacitors C f1P , C f1N . As Figure 2 shown, the first compensation resistor R fP is coupled to the first compensation capacitor C f1P and the positive output terminal V 3OP of the last-stage amplifier 216, while the first compensation capacitor C f1P is coupled to the first compensation resistor R fP and the positive input terminal V 2IP of the intermediate-stage amplifier 214. The first compensation resistor R fN is coupled to the first compensation capacitor C f1N and the negative output terminal V 3ON of the last-stage amplifier 216, while the first compensation capacitor C f1N is coupled to the first compensation resistor R fN and the negative input terminal V 2IN of the intermediate-stage amplifier 214.

[0047] The second feedback circuit includes the second compensation capacitors C f2P , C f2NFor another example Figure 2 As shown, the second compensation capacitor C f2P is coupled to the first compensation resistor R fP and the positive input terminal V of the final-stage amplifier 116 3IP to provide positive feedback. The second compensation capacitor C f2N is coupled to the first compensation resistor R fN and the negative input terminal V of the final-stage amplifier 116 3IN to provide positive feedback.

[0048] The negative feedback circuit includes a third feedback circuit and a fourth feedback circuit. Specifically, the third feedback circuit includes third compensation resistors R mP 、R mN and third compensation capacitors C m1P 、C m1N . As Figure 2 shown, the third compensation resistor R mP is coupled to the third compensation capacitor C m1P and the positive output terminal V of the final-stage amplifier 216 3OP , while the third compensation capacitor C m1P is coupled to the third compensation resistor R mP and the negative input terminal V of the intermediate-stage amplifier 214 2IN . The third compensation resistor R mN is coupled to the third compensation capacitor C m1N and the negative output terminal V of the final-stage amplifier 216 3ON , while the third compensation capacitor C m1N is coupled to the third compensation resistor R mN and the positive input terminal V of the intermediate-stage amplifier 214 2IP .

[0049] The fourth feedback circuit includes fourth compensation capacitors C m2P 、C m2N . For another example Figure 2 shown, the fourth compensation capacitor C m2P is coupled to the third compensation resistor R mP and the negative input terminal V of the final-stage amplifier 116 3IN to provide negative feedback. The fourth compensation capacitor C m2N is coupled to the third compensation resistor R mN and the positive input terminal V of the final-stage amplifier 116 3IP to provide negative feedback.

[0050] Through the above positive feedback circuit design, the amplifier circuits 100 and 200 of the present invention application can increase the 3dB bandwidth without affecting the unity gain frequency. In addition, through the above multi-stage amplifier design, the amplifier circuits 100 and 200 of the present invention application can increase the gain.

[0051] Although the content of the present invention application has been disclosed above through specific embodiments, these multiple embodiments are not intended to limit the content of the present invention application. Those of ordinary skill in the art can modify or adjust the technical solutions of the present invention application without departing from the concept and scope of the content of the present invention application, based on the explicit or implicit content of the present invention application. All such changes may fall within the scope of patent protection sought by the present invention application. In other words, the scope of protection of the content of the present invention application shall be subject to the scope defined by the claims.

Claims

1. An amplifier circuit, characterized in that, The amplifier circuit includes: A multi-stage amplifier, including a first-stage amplifier, a last-stage amplifier, and at least one intermediate-stage amplifier cascaded between the first-stage amplifier and the last-stage amplifier; A first feedback circuit for coupling the positive output terminal of the last-stage amplifier back to the positive input terminal of the at least one intermediate-stage amplifier, or for coupling the negative output terminal of the last-stage amplifier back to the negative input terminal of the at least one intermediate-stage amplifier; and A second feedback circuit for coupling the positive output terminal of the last-stage amplifier back to the positive input terminal of the last-stage amplifier, or for coupling the negative output terminal of the last-stage amplifier back to the negative input terminal of the last-stage amplifier; The first feedback circuit includes a first compensation resistor and a first compensation capacitor; the first compensation resistor is coupled between the first compensation capacitor and the positive output terminal of the last-stage amplifier, and the first compensation capacitor is coupled between the first compensation resistor and the positive input terminal of the at least one intermediate-stage amplifier; or, the first compensation resistor is coupled between the first compensation capacitor and the negative output terminal of the last-stage amplifier, and the first compensation capacitor is coupled between the first compensation resistor and the negative input terminal of the at least one intermediate-stage amplifier; The second feedback circuit includes a second compensation resistor and a second compensation capacitor; the second compensation resistor is coupled between the second compensation capacitor and the positive output terminal of the last-stage amplifier, and the second compensation capacitor is coupled between the second compensation resistor and the positive input terminal of the last-stage amplifier; or, the second compensation resistor is coupled between the second compensation capacitor and the negative output terminal of the last-stage amplifier, and the second compensation capacitor is coupled between the second compensation resistor and the negative input terminal of the last-stage amplifier; The amplifier circuit further includes: a third feedback circuit for coupling the positive output terminal of the last-stage amplifier back to the negative input terminal of the at least one intermediate-stage amplifier, or for coupling the negative output terminal of the last-stage amplifier back to the positive input terminal of the at least one intermediate-stage amplifier; The third feedback circuit includes a third compensation resistor and a third compensation capacitor; the third compensation resistor is coupled between the third compensation capacitor and the positive output terminal of the last-stage amplifier, and the third compensation capacitor is coupled between the third compensation resistor and the negative input terminal of the at least one intermediate-stage amplifier; or, the third compensation resistor is coupled between the third compensation capacitor and the negative output terminal of the last-stage amplifier, and the third compensation capacitor is coupled between the third compensation resistor and the positive input terminal of the at least one intermediate-stage amplifier; The amplifier circuit further includes: a fourth feedback circuit; the fourth feedback circuit includes a fourth compensation resistor and a fourth compensation capacitor; the fourth compensation resistor is coupled to the fourth compensation capacitor and the positive output terminal of the last-stage amplifier, and the fourth compensation capacitor is coupled to the third compensation resistor and the negative input terminal of the last-stage amplifier; alternatively, the fourth compensation resistor is coupled to the fourth compensation capacitor and the negative output terminal of the last-stage amplifier, and the fourth compensation capacitor is coupled to the third compensation resistor and the positive input terminal of the last-stage amplifier.

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