Push-pull output driver and operational amplifier using same

Patent metadata

Field	Value
Publication number	US-11070181-B2
Application number	US-201916432536-A
Country	US
Kind code	B2
Filing date	Jun 5, 2019
Priority date	Nov 20, 2018
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

A voltage driver circuit for an output stage of an operational amplifier, or other circuits, includes a level shifter and an output driver including a source follower and a common source amplifier in a push-pull configuration. The level shifter generates a node voltage as a function of an input voltage on the input node. The output driver including a first transistor having a control terminal receiving the node voltage, and connected between a supply voltage and an output node, and a second transistor having a control terminal receiving the input voltage from the input node, and connected between the output node and a reference voltage, wherein the first and second transistors have a common conductivity type.

First claim

What is claimed is:

1. A voltage driver circuit, comprising:
a level shifter having an input node, which generates a node voltage as a function of an input voltage on the input node; and
an output driver including a first transistor having a control terminal receiving the node voltage, and connected between a supply voltage and an output node, and a second transistor having a control terminal receiving the input voltage from the input node, and connected between the output node and a reference voltage, wherein the first and second transistors have a common conductivity type; wherein the level shifter includes a bias current source and a third transistor connected in series between the supply voltage and the reference voltage, the third transistor having a control terminal receiving the input voltage from the input node.

2. The circuit of claim 1 , wherein the first and second transistors are field effect transistors.

3. The circuit of claim 1 , wherein the first transistor is configured as a source follower, and the second transistor is configured as a common source amplifier.

4. The circuit of claim 1 , wherein the third transistor has a current carrying node at which the node voltage is generated.

5. The circuit of claim 1 , wherein the first, second and third transistors are field effect transistors.

6. The circuit of claim 1 , wherein the first transistor is configured as a source follower, and the second transistor is configured in current mirror configuration with the third transistor.

7. The circuit of claim 1 , wherein the bias current source comprises a fourth transistor in series between the supply voltage and the third transistor, having a conductivity type different than the third transistor.

8. The circuit of claim 1 , wherein the first and second transistors are bipolar transistors.

9. The circuit of claim 1 , wherein the first and second transistors are bipolar transistors; and
the first transistor is configured as an emitter follower, and the second transistor is configured in current mirror configuration with the third transistor.

10. An operational amplifier circuit, comprising:
an input stage having first and second inputs, which generates a first node voltage at a first circuit node as a function of voltages on the first and second inputs;
a level shifter connected to the first circuit node, which generates a second node voltage on a second circuit node as a function of the first node voltage; and
an output driver including a first transistor having a control terminal receiving the second node voltage, and connected between a supply voltage and an output node, and a second transistor having a control terminal receiving the first node voltage from the first circuit node, and connected between the output node and a reference voltage, wherein the first and second transistors have a common conductivity type; wherein the level shifter includes a bias current source and a third transistor connected in series between the supply voltage and the reference voltage, the third transistor having a control terminal receiving the first node voltage from the first circuit node.

11. The circuit of claim 10 , wherein the first and second transistors are field effect transistors.

12. The circuit of claim 10 , wherein the first transistor is configured as a source follower, and the second transistor is configured as a common source amplifier.

13. The circuit of claim 10 , wherein the bias current source comprises a fourth transistor in series between the supply voltage and the third transistor, having a conductivity type different than the third transistor.

14. The circuit of claim 10 , wherein the third transistor has a current carrying node connected to the second circuit node, and to the bias current source.

15. The circuit of claim 10 , wherein the first transistor is configured as a source follower, and the second transistor is configured in current mirror configuration with the third transistor.

16. The circuit of claim 10 , wherein the first and second transistors are bipolar transistors; and
the first transistor is configured as an emitter follower, and the second transistor is configured in current mirror configuration with the third transistor.

17. The circuit of claim 10 , wherein the input stage comprises a differential amplifier.

18. An operational amplifier circuit, comprising:
a differential amplifier having first and second inputs, which generates a first node voltage at a first circuit node as a function of voltages on the first and second inputs;
a level shifter connected to the first circuit node, includes a bias current source and a third transistor connected in series between a supply voltage and a reference voltage, the third transistor having a gate receiving the first node voltage from the first circuit node and a drain at which a second node voltage is generated; and
an output driver including a first transistor having a gate receiving the second node voltage, and connected between the supply voltage and an output node, and a second transistor having a gate receiving the first node voltage from the first circuit node, and connected between the output node and the reference voltage, wherein the first and second transistors have a common conductivity type, wherein the first transistor is configured as a source follower, and the second transistor is configured as a common source amplifier.

Assignees

• Macronix Int Co Ltd

Inventors

• Yang Yih-Shan

Classifications

• H03F3/30

  Single-ended push-pull {[SEPP]} amplifiers {(single-ended sense amplifiers G11C7/067)}; Phase-splitters therefor · CPC title

• H03F3/45273

  Mirror types · CPC title

• H03F3/45632 Primary

  in differential amplifiers with FET transistors as the active amplifying circuit (H03F3/4578 takes precedence) · CPC title

• H03F3/45174

  Mirror types · CPC title

• H03F3/45484

  in differential amplifiers with bipolar transistors as the active amplifying circuit (H03F3/4578 takes precedence) · CPC title