Differential amplifier and method for enhancing gain of a differential amplifier

Patent metadata

Field	Value
Publication number	US-12519439-B2
Application number	US-202217826692-A
Country	US
Kind code	B2
Filing date	May 27, 2022
Priority date	May 28, 2021
Publication date	Jan 6, 2026
Grant date	Jan 6, 2026

Abstract

A differential amplifier is provided. The differential amplifier includes a first single-ended amplifying means including at least a first terminal and a second terminal, a second single-ended amplifying means including at least a first terminal and a second terminal, a first transmission line, and a second transmission line. In this context, the first terminal of the first single-ended amplifying means is connected to the second terminal of the second single-ended amplifying means via the first transmission line. In addition to this, the first terminal of the second single-ended amplifying means is connected to the second terminal of the first single-ended amplifying means via the second transmission line.

First claim

What is claimed is:

1 . A differential amplifier comprising:
a first single-ended amplifier comprising a first terminal and a second terminal; a second single-ended amplifier comprising a first terminal and a second terminal; a first transmission line; and a second transmission line, wherein the first terminal of the first single-ended amplifier is connected to the second terminal of the second single-ended amplifier via a first series connection of the first transmission line, a first capacitance, and a first inductance, and wherein the first terminal of the second single-ended amplifier is connected to the second terminal of the first single-ended amplifier via a second series connection of the second transmission line, a second capacitance, and a second inductance.

2 . The differential amplifier according to claim 1 ,
wherein a value of the first capacitance is between 50 femtofarad and 200 femtofarad or between 100 femtofarad and 150 femtofarad, per millimeter of a length of the first transmission line, and wherein a value of the second capacitance is between 50 femtofarad and 200 femtofarad or between 100 femtofarad and 150 femtofarad, per millimeter of a length of the second transmission line.

3 . The differential amplifier according to claim 1 ,
wherein a value of the first capacitance is between one and three times or between 1.5 and 2.5 times a value of a first-terminal-to-second-terminal capacitance of the first single-ended amplifier, and wherein a value of the second capacitance is between one and three times or between 1.5 and 2.5 times a value of a first-terminal-to-second-terminal capacitance of the second single-ended amplifier.

4 . The differential amplifier according to claim 1 , wherein:
a third passive element network is further included as part of the first series connection; and a fourth passive element network is further included as part of the second series connection.

5 . The differential amplifier according to claim 4 ,
wherein the third passive element network comprises a third inductance, and wherein the fourth passive element network comprises a fourth inductance.

6 . The differential amplifier according to claim 1 ,
wherein a length of the first transmission line is at least 50 micrometers or at least 100 micrometers, and wherein a length of the second transmission line is at least 50 micrometers or at least 100 micrometers.

7 . The differential amplifier according to claim 1 ,
wherein the first single-ended amplifier comprises a first transistor, wherein the first terminal of the first single-ended amplifier is connected to a gate terminal of the first transistor and the second terminal of the first single-ended amplifier is connected to a drain terminal of the first transistor, and wherein the second single-ended amplifier comprises a second transistor, wherein the first terminal of the second single-ended amplifier is connected to a gate terminal of the second transistor and the second terminal of the second single-ended amplifier is connected to a drain terminal of the second transistor.

8 . A method for gain adjustment of a differential amplifier, the method comprising:
providing a first single-ended amplifier comprising a first terminal and a second terminal, a second single-ended amplifier comprising a first terminal and a second terminal, a first transmission line, and a second transmission line, connecting the first terminal of the first single-ended amplifier to the second terminal of the second single-ended amplifier via a first series connection of the first transmission line, a first capacitance, and a first inductance, and connecting the first terminal of the second single-ended amplifier to the second terminal of the first single-ended amplifier via a second series connection of the second transmission line, a second capacitance, and a second inductance.

9 . The method according to claim 8 , further comprising tracking a stability factor of the differential amplifier.

10 . The method according to claim 8 , further comprising:
configuring a coupling between the first terminal of the first single-ended amplifier and the second terminal of the second single-ended amplifier such that a stability factor of the differential amplifier is nearly equal to one; and configuring a coupling between the first terminal of the second single-ended amplifier and the second terminal of the first single-ended amplifier such that a corresponding stability factor of the differential amplifier is nearly equal to one.

11 . The method according to claim 8 , further comprising:
using the differential amplifier to amplify a signal having a wavelength, wherein a length of the first transmission line is between a twentieth and a quarter, or between a fifteenth and a sixth, of the wavelength, and wherein a length of the second transmission line is between a twentieth and a quarter, or between a fifteenth and a sixth, of the wavelength.

Assignees

• Imec Vzw
• Univ Brussel Vrije

Inventors

• Park Sehoon
• Park Daewoong
• Wambacq Pierre
• Craninckx Jan

Classifications

• H03G2201/103

  being an amplifying element · CPC title

• H03F3/45475

  using IC blocks as the active amplifying circuit · CPC title

• H03F3/45278

  using BiFET transistors as the active amplifying circuit · CPC title

• H03F2200/36

  the amplifier comprising means for increasing the bandwidth · CPC title

• H03F2203/45644

  the LC comprising a cross coupling circuit, e.g. comprising two cross-coupled transistors · CPC title