Operational amplifier

• US 8,193,862 B2
• Filed: 08/31/2010
• Issued: 06/05/2012
• Est. Priority Date: 09/11/2009
• Status: Expired due to Fees

• Current Assignee: RICOH Electronic Devices Co., Ltd. (Nisshinbo Holdings Incorporated)
• Original Assignee: Ricoh Company Limited
• Inventors: Adachi, Koichiro
• Primary Examiner(s): Choe, Henry
• Application Number:
  US12/872,239
• Publication Number:
  US 20110063036A1
• Time in Patent Office: 644 Days
• Field of Search: 330/69, 330/255, 330/260, 330/261
• US Class Current: 330/255
• CPC Class Codes: H03F 2200/405 the output amplifying stage of an amplifier comprising more than three power stages
• CPC Class Codes: H03F 2200/516 Some amplifier stages of an amplifier use supply voltages of different value
• CPC Class Codes: H03F 2200/555 A voltage generating circuit being realised for biasing different circuit elements
• CPC Class Codes: H03F 3/3022 CMOS common source output SEPP amplifiers H03F3/3008 takes precedence
• CPC Class Codes: H03F 3/45094 Folded cascode stages

Abstract

A multi-stage amplification type class-AB operational amplifier disclosed includes an amplification stage having plural amplification sections formed in multiple stages, and a class-AB output stage having a bias section and an output section, in which an input signal input to the amplification stage is sequentially amplified by the plural amplification sections, and further amplified by the bias section and the output section of the class-AB output stage. A positive supply voltage applied to the amplification stage is different from a positive supply voltage applied to the class-AB output stage, and a negative supply voltage applied to the amplification stage is different from a negative supply voltage applied to the class-AB output stage.

Claims

1. A multi-stage amplification type class-AB operational amplifier comprising:

an amplification stage having plural amplification sections formed in multiple stages; and

a class-AB output stage having a bias section and an output section, wherein

an input signal input to the amplification stage is sequentially amplified by the plural amplification sections, and further amplified by the bias section and the output section of the class-AB output stage,

a positive supply voltage applied to the amplification stage is different from a positive supply voltage applied to the class-AB output stage,

a negative supply voltage applied to the amplification stage is different from a negative supply voltage applied to the class-AB output stage,

the positive supply voltage applied to the amplification stage is equal to or greater than the positive supply voltage applied to the class-AB output stage, and

the negative supply voltage applied to the amplification stage is equal to or less than the negative supply voltage applied to the class-AB output stage.

2. The multi-stage amplification type class-AB operational amplifier according to claim 1, wherein

the bias section is formed in a manner such that a drain of an n-channel MOS transistor and a source of a p-channel MOS transistor are connected to each other, and a source of the n-channel MOS transistor and a drain of the p-channel MOS transistor are connected to each other, and

the positive supply voltage applied to the amplification stage is applied to a first generation circuit generating a gate voltage of the n-channel MOS transistor.

3. The multi-stage amplification type class-AB operational amplifier according to claim 1, wherein

the bias section is formed in a manner such that a drain of an n-channel MOS transistor and a source of a p-channel MOS transistor are connected to each other, and a source of the n-channel MOS transistor and a drain of the p-channel MOS transistor are connected to each other, and

the negative supply voltage applied to the amplification stage is applied to a second generation circuit generating a gate voltage of the p-channel MOS transistor.

4. The multi-stage amplification type class-AB operational amplifier according to claim 1, wherein

the positive supply voltage applied to the amplification stage, the positive supply voltage applied to the class-AB output stage, the negative supply voltage applied to the amplification stage, and the negative supply voltage applied to the class-AB output stage are fixed voltages.

5. The multi-stage amplification type class-AB operational amplifier according to claim 1, wherein

the positive supply voltage and the negative supply voltage applied to the amplification stage are one of variable voltages based on external signal control and fixed voltages, and the positive supply voltage and the negative supply voltage applied to the class-AB output stage are the other one of the variable voltages based on external signal control and the fixed voltages.

6. The multi-stage amplification type class-AB operational amplifier according to claim 1, wherein

the positive supply voltage applied to the amplification stage, the positive supply voltage applied to the class-AB output stage, the negative supply voltage applied to the amplification stage, and the negative supply voltage applied to the class-AB output stage are variable voltages based on external signal control, and

a control signal controlling the positive supply voltage and the negative supply voltage applied to the amplification stage is a same as or different from a control signal controlling the positive supply voltage and the negative supply voltage applied to the class-AB output stage.

7. A multi-stage amplification type class-AB operational amplifier comprising:

an amplification stage having plural amplification sections formed in multiple stages; and

a class-AB output stage having a bias section and an output section, wherein

an input signal input to the amplification stage is sequentially amplified by the plural amplification sections, and further amplified by the bias section and the output section of the class-AB output stage,

a positive supply voltage applied to the amplification stage is different from a positive supply voltage applied to the class-AB output stage, and

the positive supply voltage applied to the amplification stage is equal to or greater than the positive supply voltage a shed to the class-AB output stage.

8. The multi-stage amplification type class-AB operational amplifier according to claim 7, wherein

the bias section is formed in a manner such that a drain of an n-channel MOS transistor and a source of a p-channel MOS transistor are connected to each other, and a source of the n-channel MOS transistor and a drain of the p-channel MOS transistor are connected to each other, and

the positive supply voltage applied to the amplification stage is applied to a first generation circuit generating a gate voltage of the n-channel MOS transistor.

9. The multi-stage amplification type class-AB operational amplifier according to claim 7, wherein

a negative supply voltage applied to the amplification stage and a negative supply voltage applied to the class-AB output stage are one fixed voltage, and the positive supply voltage applied to the amplification stage and the positive supply voltage applied to the class-AB output stage are fixed voltages.

10. The multi-stage amplification type class-AB operational amplifier according to claim 7, wherein

the positive supply voltage applied to the amplification stage is one of a variable voltage based on external signal control and a fixed voltage, and the positive supply voltage applied to the class-AB output stage is the other one of the variable voltage based on external signal control and the fixed voltage.

11. The multi-stage amplification type class-AB operational amplifier according to claim 7, wherein

the positive supply voltage applied to the amplification stage and the positive supply voltage applied to the class-AB output stage are variable voltages based on external signal control, and

a control signal controlling the positive supply voltage applied to the amplification stage is a same as or different from a control signal controlling the positive supply voltage applied to the class-AB output stage.

12. A multi-stage amplification type class-AB operational amplifier comprising:

an amplification stage having plural amplification sections formed in multiple stages; and

a class-AB output stage having a bias section and an output section, wherein an input signal input to the amplification stage is sequentially amplified by the plural amplification sections and further amplified by the bias section and the output section of the class-AB output stage,

a negative supply voltage applied to the amplification stage is different from a negative supply voltage applied to the class-AB output stage, and

the negative supply voltage applied to the amplification stage is equal to or than the negative supply voltage applied to the class-AB output stage.

13. The multi-stage amplification type class-AB operational amplifier according to claim 12, wherein

the bias section is formed in a manner such that a drain of an n-channel MOS transistor and a source of a p-channel MOS transistor are connected to each other, and a source of the n-channel MOS transistor and a drain of the p-channel MOS transistor are connected to each other, and

the negative supply voltage applied to the amplification stage is applied to a second generation circuit generating a gate voltage of the p-channel MOS transistor.

14. The multi-stage amplification type class-AB operational amplifier according to claim 12, wherein

a positive supply voltage applied to the amplification stage and a positive supply voltage applied to the class-AB output stage are one fixed voltage, and the negative supply voltage applied to the amplification stage and the negative supply voltage applied to the class-AB output stage are fixed voltages.

15. The multi-stage amplification type class-AB operational amplifier according to claim 12, wherein

the negative supply voltage applied to the amplification stage is one of a variable voltage based on external signal control and a fixed voltage, and the negative supply voltage applied to the class-AB output stage is the other one of the variable voltage based on external signal control and the fixed voltage.

16. The multi-stage amplification type class-AB operational amplifier according to claim 12, wherein

the negative supply voltage applied to the amplification stage and the negative supply voltage applied to the class-AB output stage are variable voltages based on external signal control, and

a control signal controlling the negative supply voltage applied to the amplification stage is a same as or different from a control signal controlling the negative supply voltage applied to the class-AB output stage.