Variable-gain amplifier with degeneration circuit

Patent metadata

Field	Value
Publication number	US-11245372-B2
Application number	US-202017005244-A
Country	US
Kind code	B2
Filing date	Aug 27, 2020
Priority date	Aug 30, 2019
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

This disclosure relates to variable-gain amplifiers that include degeneration circuits configured to adapt to a gain mode that is currently being implemented. For example, a variable-gain amplifier can operate in a plurality of gain modes to amplify a signal with different levels of amplification. The variable-gain amplifier can include a gain circuit configured to amplify a signal and a degeneration circuit coupled to the gain circuit. The degeneration circuit can include an inductor and a switching-capacitive arm coupled in parallel to the inductor. The degeneration circuit can operate based on a current gain mode to change an inductance for the variable-gain amplifier.

First claim

What is claimed is:

1. A variable-gain amplifier comprising:
a gain circuit configured to amplify a signal and to operate in a plurality of gain modes; and
a degeneration circuit coupled to the gain circuit, the degeneration circuit including an inductor and a switching-capacitive arm coupled in parallel to the inductor, the switching-capacitive arm including a capacitor and a switch coupled in series,
wherein the switch is configured to be placed in:
an open state when the gain circuit operates in a first gain mode from among the plurality of gain modes; and
a closed state when the gain circuit operates in a second gain mode from among the plurality of gain modes, the first gain mode being associated with more gain than the second gain mode.

2. The variable-gain amplifier of claim 1 wherein the switch includes at least one of a transistor or a mechanical switch.

3. The variable-gain amplifier of claim 1 wherein the switching-capacitive arm is a first switching-capacitive arm and the degeneration circuit further includes a second switching-capacitive arm coupled in parallel to the inductor.

4. The variable-gain amplifier of claim 1 wherein the gain circuit includes a transistor having a gate or base coupled to an input node and a drain or collector coupled to an output node, and the degeneration circuit is coupled to a source or emitter of the transistor.

5. The variable-gain amplifier of claim 1 wherein the variable-gain amplifier is implemented within a low noise amplifier.

6. The variable-gain amplifier of claim 1 wherein the gain circuit includes a transistor, and wherein the inductor, the switching-capacitive arm, and a source or emitter of the transistor are coupled to a common node.

7. A variable-gain amplifier comprising:
a transistor including a gate or base coupled to an input node and a drain or collector coupled to an output node; and
a degeneration circuit coupled to a source or emitter of the transistor, the degeneration circuit including an inductor and a switching-capacitive arm coupled in parallel to the inductor, the switching-capacitive arm including a capacitor and a switch coupled in series,
wherein the switch is configured to be placed in:
an open state when the variable-gain amplifier implements a first gain mode; and
a closed state when the variable-gain amplifier implements a second gain mode, the first gain mode being associated with more gain than the second gain mode.

8. The variable-gain amplifier of claim 7 wherein the switch includes one or more of a transistor or a mechanical switch.

9. The variable-gain amplifier of claim 7 wherein the switching-capacitive arm is a first switching-capacitive arm and the degeneration circuit further includes a second switching-capacitive arm coupled in parallel to the inductor.

10. The variable-gain amplifier of claim 7 wherein the variable-gain amplifier is implemented within a low noise amplifier.

11. The variable-gain amplifier of claim 7 wherein the inductor, the switching-capacitive arm, and the source or emitter of the transistor are coupled to a common node.

12. A radio-frequency module comprising:
a low noise amplifier configured to amplify a first signal;
a power amplifier configured to amplify a second signal; and
a controller coupled to at least one of the low noise amplifier or the power amplifier,
wherein at least one of the low noise amplifier or the power amplifier includes a transistor and a degeneration circuit coupled to the transistor, the transistor including a gate or base coupled to an input node and a drain or collector coupled to an output node, the degeneration circuit including an inductor and a switching-capacitive arm coupled in parallel to the inductor, the switching-capacitive arm including a capacitor and a switch coupled in series, and
wherein the controller is configured to:
control the switch to implement an open state for a first gain mode; and
control the switch to implement a closed state for a second gain mode, the first gain mode being associated with more gain than the second gain mode.

13. The radio-frequency module of claim 9 wherein the switch includes at least one of a transistor or a mechanical switch.

14. The radio-frequency module of claim 12 wherein the switching-capacitive arm is a first switching-capacitive arm and the degeneration circuit further includes a second switching-capacitive arm coupled in parallel to the inductor.

15. A radio-frequency device comprising:
the radio frequency module of claim 12 ; and
an antenna configured to receive the first signal and transmit the second signal.

16. The radio-frequency module of claim 12 wherein the inductor, the switching-capacitive arm, and a source or emitter of the transistor are coupled to a common node.

Assignees

• Skyworks Solutions Inc

Inventors

• Hua Xingyi
• Chang Weiheng

Classifications

• H03G2201/103

  being an amplifying element · CPC title

• H04B1/44

  Transmit/receive switching · CPC title

• H03F3/195

  in integrated circuits · CPC title

• H03F3/245 Primary

  with semiconductor devices only · CPC title

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title