Transconductance Enhanced RF Front-End

• US 20110092180A1
• Filed: 01/26/2010
• Published: 04/21/2011
• Est. Priority Date: 10/16/2009
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: CHEN, Xinyu, Chen, Calvin (Shr-Lung), Leete, John
• Granted Patent: US 8,358,991 B2
• Time in Patent Office: Days
• US Class Current: 455/341
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes

Abstract

Embodiments of an RF receiver front-end are presented herein. In an embodiment, the RF receiver front-end comprises a transconductance LNA, a passive mixer, and a g_m-enhanced common-gate buffer. The transconductance LNA is configured to convert an RF voltage signal to an RF current signal and provide the RF current signal at an output. The passive mixer is coupled to the output of the transconductance LNA and is configured to mix the RF current signal with a local oscillator signal to produce a frequency translated current signal. The g_m-enhanced common-gate buffer is configured to receive the frequency translated current signal at an input and convert the frequency translated current signal to a frequency translated voltage signal. In an embodiment, the input of the gm-enhanced common-gate buffer is configured to provide a low input impedance to limit a voltage swing of the frequency translated current signal.

Claims

1. A radio frequency (RF) receiver front-end, comprising:

a transconductance low noise amplifier (LNA) configured to convert an RF voltage signal to an RF current signal and provide the RF current signal at an output;

a passive mixer coupled to the output of the transconductance LNA and configured to mix the RF current signal with a local oscillator signal to produce a frequency translated current signal; and

a g_m-enhanced common-gate buffer configured to receive the frequency translated current signal at an input and convert the frequency translated current signal to a frequency translated voltage signal.

2. The RF receiver front-end of claim 1, where the transconductance LNA is configured as a single-stage, common-source amplifier.

3. The RF receiver front-end of claim 1, wherein the passive mixer is AC coupled to the output of the transconductance LNA.

4. The RF receiver front-end of claim 1, wherein the passive mixer is current driven.

5. The RF receiver front-end of claim 1, wherein the passive mixer comprises a first double-balanced mixer and a second double-balanced mixer.

6. The RF receiver front-end of claim 1, wherein the g_m-enhanced common-gate buffer comprises an additional amplifier configured to increase the effective transconductance of the g_m-enhanced common-gate buffer.

7. The RF receiver front-end of claim 6, wherein the effective transconductance of the g_m-enhanced common-gate buffer is increased by a factor of ‘

A’

, where ‘

A’

is substantially equal to the gain of the additional amplifier.

8. The RF receiver front-end of claim 7, wherein the common-gate buffer further comprises a transistor configured to receive the frequency translated current signal at a source terminal and provide the frequency translated voltage signal at a drain terminal.

9. The RF receiver front-end of claim 8, wherein a gate of the transistor is coupled to the output of the additional amplifier.

10. The RF receiver front-end of claim 1, wherein a capacitive filter is coupled between the passive mixer and the g_m-enhanced common-gate buffer.

11. A radio frequency (RF) receiver front-end, comprising:

a transconductance low noise amplifier (LNA) configured to convert an RF voltage signal to an RF current signal and provide the RF current signal at an output;

a passive mixer coupled to the output of the transconductance LNA and configured to mix the RF current signal with a local oscillator signal to produce a frequency translated current signal; and

a g_m-enhanced common-gate buffer configured to receive the frequency translated current signal at an input and convert the frequency translated current signal to a frequency translated voltage signal,

wherein the input of the gm-enhanced common-gate buffer is configured to provide a low input impedance to limit a voltage swing of the frequency translated current signal.

12. The RF receiver front-end of claim 11, where the transconductance LNA is configured as a single-stage, common-source amplifier.

13. The RF receiver front-end of claim 11, wherein the passive mixer is AC coupled to the output of the transconductance LNA.

14. The RF receiver front-end of claim 11, wherein the passive mixer is current driven.

15. The RF receiver front-end of claim 11, wherein the passive mixer comprises a first double-balanced mixer and a second double-balanced mixer.

16. The RF receiver front-end of claim 11, wherein the g_m-enhanced common-gate buffer comprises an additional amplifier configured to increase the effective transconductance of the g_m-enhanced common-gate buffer.

17. The RF receiver front-end of claim 16, wherein the effective transconductance of the g_m-enhanced common-gate buffer is increased by a factor of ‘

A’

, where ‘

A’

is substantially equal to the gain of the additional amplifier.

18. The RF receiver front-end of claim 17, wherein the common-gate buffer includes a transistor configured to receive the frequency translated current signal at a source terminal and provide the frequency translated voltage signal at a drain terminal.

19. The RF receiver front-end of claim 18, wherein a gate of the transistor is coupled to the output of the additional amplifier.

20. The RF receiver front-end of claim 11, wherein a capacitive filter is coupled between the passive mixer and the g_m-enhanced common-gate buffer.