Harmonic suppression for a multi-band transmitter

• US 20040127185A1
• Filed: 12/12/2003
• Published: 07/01/2004
• Est. Priority Date: 12/23/2002
• Status: Abandoned Application

• Current Assignee: GlobespanVirata, Inc. (Synaptics Incorporated)
• Original Assignee: GlobespanVirata, Inc. (Synaptics Incorporated)
• Inventors: Schultz, R. Douglas, Vitek, W. Joseph IV, Abrahams, Richard L., Harriman, Adam K.
• Application Number:
  US10/735,012
• Publication Number:
  US 20040127185A1
• Time in Patent Office: Days
• US Class Current: 455/277.1
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04B 1/006 using switches for selecting the desired band H04B1/0057 takes precedence
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes

Abstract

A multiple band transmitter including first and second transmit amplifier paths, where the first transmit amplifier path conducts a first transmit signal at a first frequency band and the second transmit amplifier path conducts a second transmit signal at a second frequency band. The second transmit amplifier path includes an amplifier that generates the second transmit signal along with a harmonic frequency within a passband of the first transmit amplifier path. The second transmit amplifier path further includes a trap circuit that shunts the harmonic frequency away from the first transmit amplifier path.

Claims

1. A multiple band transmitter, comprising:

a first transmit amplifier path conducting a first transmit signal at a first frequency band; and

a second transmit amplifier path conducting a second transmit signal at a second frequency band, said second transmit amplifier path comprising;

an amplifier that generates said second transmit signal and a harmonic frequency within a passband of said first transmit amplifier path; and

a trap circuit, coupled to an output of said amplifier, that shunts said harmonic frequency away from said first transmit amplifier path.

2. The multiple band transmitter of claim 1, wherein said trap circuit comprises a series LC circuit.

3. The multiple band transmitter of claim 2, wherein said series LC circuit is tuned to a second harmonic frequency of said second frequency band.

4. The multiple band transmitter of claim 2, wherein said series LC circuit comprises a load that cooperates with remaining portions of said second transmit amplifier path to optimize power throughput of said second transmit signal along said second transmit amplifier path.

5. The multiple band transmitter of claim 1, wherein said trap circuit comprises a transmission line.

6. The multiple band transmitter of claim 5, wherein said transmission line is tuned to a second harmonic frequency of said second frequency band.

7. The multiple band transmitter of claim 5, wherein said transmission line has a length which is approximately one-half wavelength of a second harmonic frequency of said second frequency band.

8. The multiple band transmitter of claim 1, wherein said first transmit amplifier path conducts said first transmit signal at a frequency band of approximately 5 gigahertz, and wherein said second transmit amplifier path conducts said second transmit signal at a frequency band of approximately 2.45 gigahertz.

9. The multiple band transmitter of claim 8, wherein said first and second transmit amplifier paths form a transmitter portion of a dual band wireless local area network transceiver.

10. A multiple band transmitter, comprising:

a plurality of amplifier paths, each amplifying a corresponding transmit signal at a corresponding frequency band;

said plurality of amplifier paths including a first amplifier path that generates a harmonic frequency within a passband of at least one other of said plurality of amplifier paths; and

a trap circuit, coupled to said first amplifier path, that shunts said harmonic frequency to ground.

11. The multiple band transmitter of claim 10, wherein said trap circuit comprises a series LC circuit.

12. The multiple band transmitter of claim 11, wherein said series LC circuit is tuned to said harmonic frequency.

13. The multiple band transmitter of claim 11, wherein said series LC circuit comprises a load that cooperates with remaining portions of said first amplifier path to optimize power throughput.

14. The multiple band transmitter of claim 10, wherein said trap circuit comprises a transmission line.

15. The multiple band transmitter of claim 14, wherein said transmission line is tuned to said harmonic frequency.

16. The multiple band transmitter of claim 14, wherein said transmission line has a length which is approximately one-half wavelength of said harmonic frequency.

17. The multiple band transmitter of claim 10, wherein said first amplifier path includes a power amplifier having an output that generates said harmonic frequency, and wherein said trap circuit is coupled at an output of said power amplifier.