Low noise amplifier

Patent metadata

Field	Value
Publication number	US-9735740-B2
Application number	US-201414486749-A
Country	US
Kind code	B2
Filing date	Sep 15, 2014
Priority date	Sep 15, 2014
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A low noise amplifier includes an amplifier transistor having a source, a gate, and a drain. An input node is coupled to the gate. An output node is coupled to the drain. An inductor is coupled between the gate and the drain.

First claim

What is claimed is:

1. A low noise amplifier, comprising:
an amplifier transistor having a source, a gate, and a drain;
an input node coupled to the gate;
an output node coupled to the drain;
a first inductor directly coupled between the gate and the drain; and
a second inductor directly connected between the gate and a high voltage supply node.

2. The low noise amplifier of claim 1 , wherein the first inductor is arranged to compensate a parasitic capacitance between the gate and the drain of the amplifier transistor.

3. The low noise amplifier of claim 2 , wherein the first inductor has a value based on a resonance condition of the parasitic capacitance between the gate and the drain and the first inductor.

4. The low noise amplifier of claim 3 , wherein an operating frequency of the low noise amplifier is a resonance frequency of the resonance condition.

5. The low noise amplifier of claim 4 , wherein the value of the first inductor is equal to or greater than L, L is obtained from

f
⁢

⁢
0

=

1

2
⁢
π
⁢

LC

,

fo is the resonance frequency, and C is the parasitic capacitance between the gate and the drain.

6. The low noise amplifier of claim 1 , wherein the second inductor is arranged to compensate at least part of a parasitic capacitance between the gate and the source of the amplifier transistor.

7. The low noise amplifier of claim 1 , wherein the first inductor and the second inductor are arranged to compensate at least part of parasitic capacitances between the source and the gate, and between the source and the drain of the amplifier transistor in the low noise amplifier.

8. The low noise amplifier of claim 1 , further comprising a capacitor coupled between the input node and the gate.

9. The low noise amplifier of claim 8 , wherein the capacitor is arranged to provide impedance matching for the input node of the low noise amplifier with the second inductor.

10. The low noise amplifier of claim 1 , wherein the amplifier transistor is an NMOS transistor.

11. A method, comprising:
compensating a parasitic capacitance between a gate and a drain of an amplifier transistor in a low noise amplifier using a first inductor directly coupled between the gate and the drain;
compensating at least part of parasitic capacitances between a source and the gate, and between the source and the drain of the amplifier transistor in the low noise amplifier using the first inductor and a second inductor coupled between the gate and a power supply; and
providing an output signal at an output node coupled to the drain of the amplifier transistor.

12. The method of claim 11 , further comprising matching impedance for an input node of the low noise amplifier by using the second inductor and a capacitor coupled between the input node and the gate of the amplifier transistor.

13. The method of claim 12 , wherein matching impedance is performed for 50 ohm.

14. A method, comprising:
compensating a parasitic capacitance between a gate and a drain of an amplifier transistor in a low noise amplifier using a first inductor directly coupled between the gate and the drain, wherein compensating the parasitic capacitance between the gate and the drain comprises determining a value of the first inductor based on a resonance condition of the parasitic capacitance between the gate and the drain and the first inductor; and
providing an output signal at an output node coupled to the drain of the amplifier transistor.

15. The method of claim 14 , wherein an operating frequency of the low noise amplifier is a resonance frequency of the resonance condition.

16. The method of claim 15 , wherein the value of the first inductor is equal to or greater than L, L is obtained from

f
⁢

⁢
0

=

1

2
⁢
π
⁢

LC

,

fo is the resonance frequency, and C is the parasitic capacitance between the gate and the drain.

17. A low noise amplifier, comprising:
an NMOS amplifier transistor having a source, a gate, and a drain;
an input node coupled to the gate;
an output node coupled to the drain;
a first inductor directly coupled between the gate and the drain, wherein the first inductor is arranged to compensate a parasitic capacitance between the gate and the drain of the NMOS amplifier transistor; and
a second inductor coupled between the gate and a high voltage supply node, wherein the first inductor and the second inductor are arranged to compensate at least part of parasitic capacitances between the source and the gate, and between the source and the drain of the NMOS amplifier transistor in the low noise amplifier.

18. The low noise amplifier of claim 17 , wherein the first inductor has a value based on a resonance condition of the parasitic capacitance between the gate and the drain and the first inductor, an operating frequency of the low noise amplifier is a resonance frequency of the resonance condition, and the value of the first inductor is equal to or greater than L, L is obtained from

f
⁢

⁢
0

=

1

2
⁢
π
⁢

LC

,

fo is the resonance frequency, and C is the parasitic capacitance between the gate and the drain.

19. The low noise amplifier of claim 17 , further comprising a capacitor coupled between the input node and the gate.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Jin Jun-De

Classifications

• H03F3/193

  with field-effect devices (H03F3/195 takes precedence) · CPC title

• H03F2200/294

  the amplifier being a low noise amplifier [LNA] · CPC title

• H03F2200/372

  Noise reduction and elimination in amplifier · CPC title

• H03F1/26 Primary

  Modifications of amplifiers to reduce influence of noise generated by amplifying elements · CPC title

• H03F1/565

  using inductive elements · CPC title