Operational amplifier based circuit with compensation circuit block used for stability compensation

Patent metadata

Field	Value
Publication number	US-9979350-B2
Application number	US-201514920894-A
Country	US
Kind code	B2
Filing date	Oct 23, 2015
Priority date	Nov 17, 2014
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

An operational amplifier based circuit has an operational amplifier, a feedback circuit, and a compensation circuit block. The feedback circuit is coupled between an output port and an input port of the operational amplifier. The compensation circuit block has circuits involved in stability compensation of the operational amplifier, wherein there is no stability compensation circuit driven at the output port of the operational amplifier.

First claim

What is claimed is:

1. An operational amplifier based circuit comprising:
an operational amplifier, wherein the operational amplifier is a multi-stage amplifier;
a feedback circuit, coupled between an output port and an input port of the operational amplifier; and
a compensation circuit block, comprising circuits involved in stability compensation of the operational amplifier;
wherein the compensation circuit block comprises a first part of a stability compensation circuit arranged to apply the stability compensation to the operational amplifier, and the feedback circuit is reused as a second part of the stability compensation circuit; and there is no other stability compensation circuit connected to the output port of the operational amplifier;
wherein the operational amplifier is a differential amplifier, and the stability compensation circuit is a differential-mode stability compensation circuit arranged to apply differential-mode stability compensation to the operational amplifier.

2. The operational amplifier based circuit of claim 1 , wherein the operational amplifier has an output stage, and no Miller compensation capacitor is across the output stage.

3. The operational amplifier based circuit of claim 1 , wherein the feedback circuit comprises:
a feedback network, comprising:
a first node, coupled to one input node of the input port; and
a second node, coupled to one output node of the output port;

the compensation circuit block comprises:
a compensation circuit, coupled to the first node of the feedback network and said one input node of the input port, wherein one input signal of the operational amplifier based circuit is received through the compensation circuit.

4. The operational amplifier based circuit of claim 3 , wherein the compensation circuit comprises a resistive component and a capacitive component connected in series, and said one input signal of the operational amplifier based circuit is received at an interconnection node between the resistive component and the capacitive component.

5. The operational amplifier based circuit of claim 4 , wherein said input signal of the operational amplifier based circuit is a mixer output, and the resistive component and the capacitive component are arranged as a low-pass filter with no blocker suppression on a signal channel edge.

6. The operational amplifier based circuit of claim 1 , wherein the operational amplifier is a multi-stage amplifier having an output stage, the feedback circuit comprises:
a first feedback network, comprising:
a first node, coupled to one input node of the input port; and
a second node, coupled to one output node of the output port;

the compensation circuit block comprises:
a first compensation circuit, coupled between the first node of the first feedback network and one input node of the output stage.

7. The operational amplifier based circuit of claim 6 , wherein the first compensation circuit comprises at least a capacitive component.

8. The operational amplifier based circuit of claim 6 , wherein the multi-stage amplifier is a differential amplifier, and the compensation circuit block further comprises:
a second compensation circuit, coupled between the first node of the first feedback network and another input node of the output stage.

9. The operational amplifier based circuit of claim 8 , wherein the feedback circuit further comprises:
a second feedback network, comprising:
a first node, coupled to another input node of the input port; and
a second node, coupled to another output node of the output port;

the compensation circuit block further comprises:
a third compensation circuit, coupled between the first node of the second feedback network and said another input node of the output stage; and
a fourth compensation circuit, coupled between the first node of the second feedback network and said one input node of the output stage.

10. The operational amplifier based circuit of claim 9 , wherein the first compensation circuit, the second compensation circuit, the third compensation circuit, and the fourth compensation circuit are arranged in a cross-coupled connection fashion.

11. An operational amplifier based circuit comprising:
a multi-stage operational amplifier, comprising an output stage;
a feedback circuit, coupled between an output port and an input port of the multi-stage operational amplifier, the feedback circuit comprising:
a first feedback network, comprising:
a first node, coupled to one input node of the input port; and
a second node, coupled to one output node of the output port; and

a compensation circuit block, comprising circuits involved in stability compensation of the multi-stage operational amplifier, the compensation circuit block comprising:
a first compensation circuit, coupled between the first node of the feedback network and one input node of the output stage;

wherein the compensation circuit block comprises a first part of a stability compensation circuit arranged to apply the stability compensation to the operational amplifier, and the feedback circuit is reused as a second part of the stability compensation circuit.

12. The operational amplifier based circuit of claim 11 , wherein the first compensation circuit comprises at least a capacitive component.

13. The operational amplifier based circuit of claim 11 , wherein the multi-stage operational amplifier is a differential amplifier, and the compensation circuit block further comprises:
a second compensation circuit, coupled between the first node of the first feedback network and another input node of the output stage.

14. The operational amplifier based circuit of claim 13 , wherein the feedback circuit further comprises:
a second feedback network, comprising:
a first node, coupled to another input node of the input port; and
a second node, coupled to another output node of the output port;

the compensation circuit block further comprises:
a third compensation circuit, coupled between the first node of the second feedback network and said another input node of the output stage; and
a fourth compensation circuit, coupled between the first node of the second feedback network and said one input node of the output stage.

15. The operational amplifier based circuit of claim 14 , wherein the first compensation circuit, the second compensation circuit, the third compensation circuit, and the fourth compensation circuit are arranged in a cross-coupled connection fashion.

16. An operational amplifier based circuit comprising:
a differential operational amplifier;
a feedback circuit, coupled between an output port and an input port of the differential operational amplifier; and
a compensation circuit block, comprising circuits involved in stability compensation of the differential operational amplifier;
wherein the compensation circuit block comprises a first part of a common-mode stability compensation circuit arranged to apply common-mode stability compensation to the differential operational amplifier, and the feedback circuit is reused as a second part of the common-mode stability compensation circuit.

17. An operational amplifier based circuit comprising:
an operational amplifier;
a feedback circuit, coupled between an output port and an input port of the operational amplifier; and
a compensation circuit block, comprising circuits involved in stability compensation of the operational amplifier;
wherein the compensation circuit block comprises a first part of a stability compensation circuit arranged to apply the stability compensation

Assignees

• Mediatek Inc

Inventors

• Yu Chi-Yao

Classifications

• H03F3/45659

  Controlling the loading circuit of the differential amplifier · CPC title

• H03F2203/45338

  the AAC comprising one or more series circuits of a resistor and a capacitor as feedback circuit elements · CPC title

• H03F2203/45631

  the LC comprising one or more capacitors, e.g. coupling capacitors · CPC title

• H03F2203/45188

  the differential amplifier contains one or more current sources in the load · CPC title

• H03F2200/411

  the output amplifying stage of an amplifier comprising two power stages · CPC title