Orthogonal frequency division multiplexing transceiver and method of operating the same

• US 20040235444A1
• Filed: 05/19/2003
• Published: 11/25/2004
• Est. Priority Date: 05/19/2003
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Draijer, Gert
• Granted Patent: US 7,058,379 B2
• Time in Patent Office: Days
• US Class Current: 455/208
• CPC Class Codes: H04B 1/403 using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency

Abstract

For use in an orthogonal frequency division multiplexing (OFDM) transceiver, a multimode local oscillator circuit and a method of operating the same. In one embodiment, the circuit includes: (1) a single sideband mixer having an output, first and second inputs and a local oscillator input and (2) a signal generator, coupled to the single sideband mixer, for alternatively providing to the first and second inputs: (2a) constant values to cause the single sideband mixer to generate a first receiver local oscillator signal for operating the OFDM transceiver as a zero intermediate frequency receiver and (2b) a first orthogonal baseband signal to cause the single sideband mixer to generate a second receiver local oscillator signal for operating the OFDM transceiver as a low intermediate frequency receiver.

Claims

1. For use in an orthogonal frequency division multiplexing (OFDM) transceiver, a multimode local oscillator circuit, comprising:

a single sideband mixer having an output, first and second inputs and a local oscillator input; and

a signal generator, coupled to said single sideband mixer, for alternatively providing to said first and second inputs;

constant values to cause said single sideband mixer to generate a first receiver local oscillator signal for operating said OFDM transceiver as a zero intermediate frequency receiver, and

a first orthogonal baseband signal to cause said single sideband mixer to generate a second receiver local oscillator signal for operating said OFDM transceiver as a low intermediate frequency receiver.

2. The circuit as recited in claim 1 wherein said signal generator alternatively provides to said first and second inputs a second orthogonal baseband signal to generate a transmit signal for operating said OFDM transceiver as a transmitter.

3. The circuit as recited in claim 1 wherein said single sideband mixer comprises first and second phase offset circuits, coupled to said local oscillator input, for generating first and second orthogonal local oscillator signals.

4. The circuit as recited in claim 1 further comprising a mode switch, coupled to said output, for toggling said OFDM transceiver between receiver and transmitter modes.

5. The circuit as recited in claim 1 wherein said first orthogonal baseband signal is a wave selected from the group consisting of:

a sinewave, and

a square wave.

6. The circuit as recited in claim 1 wherein said OFDM transceiver comprises a second single sideband mixer for receiving one of said first and second receiver local oscillator signal when said OFDM transceiver is operating as said receiver.

7. The circuit as recited in claim 1 wherein said OFDM transceiver and said a multimode local oscillator circuit are embodied in a single integrated circuit.

8. For use in an orthogonal frequency division multiplexing (OFDM) transceiver, a method of operating a multimode local oscillator circuit, comprising:

providing constant values to first and second inputs of a single sideband mixer to cause said single sideband mixer to generate a first receiver local oscillator signal at an output thereof for operating said OFDM transceiver as a zero intermediate frequency receiver, and

alternatively providing a first orthogonal baseband signal to said first and second inputs to cause said single sideband mixer to generate a second receiver local oscillator signal for operating said OFDM transceiver as a low intermediate frequency receiver.

9. The method as recited in claim 8 further comprising alternatively providing a second orthogonal baseband signal to said first and second inputs to cause said single sideband mixer to generate a transmit signal for operating said OFDM transceiver as a transmitter.

10. The method as recited in claim 8 further comprising generating first and second orthogonal local oscillator signals with first and second phase offset circuits.

11. The method as recited in claim 8 further comprising toggling said OFDM transceiver between receiver and transmitter modes.

12. The method as recited in claim 8 wherein said first orthogonal baseband signal is a wave selected from the group consisting of:

a sinewave, and

a square wave.

13. The method as recited in claim 8 further comprising employing a second single sideband mixer in said OFDM transceiver for receiving one of said first and second receiver local oscillator signal when said OFDM transceiver is operating as said receiver.

14. The method as recited in claim 8 wherein said method is carried out in a single integrated circuit.

15. An orthogonal frequency division multiplexing (OFDM) transceiver, comprising:

signal demodulating circuitry including at least one filter;

a multimode local oscillator circuit, coupled to said signal demodulating circuitry and including;

a single sideband mixer having an output, first and second inputs and a local oscillator input, and

a signal generator, coupled to said single sideband mixer, for alternatively providing to said first and second inputs;

constant values to cause said single sideband mixer to generate a first receiver local oscillator signal for operating said OFDM transceiver as a zero intermediate frequency receiver, and

a first orthogonal baseband signal to cause said single sideband mixer to generate a second receiver local oscillator signal for operating said OFDM transceiver as a low intermediate frequency receiver.

16. The OFDM transceiver as recited in claim 15 wherein said signal generator alternatively provides to said first and second inputs a second orthogonal baseband signal to cause said single sideband mixer to generate a transmit signal for operating said OFDM transceiver as a transmitter.

17. The OFDM transceiver as recited in claim 15 wherein said single sideband mixer comprises first and second phase offset circuits, coupled to said local oscillator input, for generating first and second orthogonal receiver local oscillator signals.

18. The OFDM transceiver as recited in claim 15 further comprising a mode switch, coupled to said output, for toggling said OFDM transceiver between receiver and transmitter modes.

19. The OFDM transceiver as recited in claim 15 wherein said first orthogonal baseband signal is a wave selected from the group consisting of:

a sinewave, and

a square wave.

20. The OFDM transceiver as recited in claim 15 wherein signal demodulating circuitry comprises a second single sideband mixer for receiving one of said first and second receiver local oscillator signal when said OFDM transceiver is operating as said receiver.

21. The OFDM transceiver as recited in claim 15 wherein said OFDM transceiver and said multimode local oscillator circuit are embodied in a single integrated circuit.