Reconfigurable topology for receiver front ends

• US 20070141998A1
• Filed: 12/21/2005
• Published: 06/21/2007
• Est. Priority Date: 12/21/2005
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Zolfaghari, Alireza
• Granted Patent: US 7,587,224 B2
• Time in Patent Office: Days
• US Class Current: 455/78
• CPC Class Codes: H04B 1/40 Circuits

Abstract

The method and apparatus of the present invention provide for a configurable radio front end topology that allows selectable operation in a single balanced mode and in a double balanced mode of operation. Logic associated with a baseband processor determines whether to operate in a single or double balanced mode of operation and produces the mode control signal to control selective coupling of circuit components according to the specified mode. Switching circuitry is used to switch a Balun in and out of connectivity. Further, a pair of LO polarity blocks are operable to determine the polarity of a differential LO received by associated mixers according to whether a single balanced or double balanced mode is in use.

Claims

1. An integrated circuit radio transceiver, comprising:

a radio front end operable to receive ingoing radio frequency (RF) signals and to produce ingoing digital signals based upon the ingoing RF signals and further operable to receive outgoing digital signals and to produce outgoing RF signals;

a baseband processor operably coupled to the radio front end to receive the ingoing digital signals and to produce the outgoing digital signals; and

wherein the radio front end further includes;

a configurable input stage that is operable in a single balanced mode and in a double balanced mode; and

logic for switching between the single balanced mode and the double balanced mode.

2. The integrated circuit radio transceiver of claim 1 wherein the configurable input stage further includes:

first and second low noise amplifiers operable to produce first and second amplified ingoing RF signals;

first and second mixers operably disposed to receive the first amplified ingoing RF signals; and

third and fourth mixers operably disposed to receive the second amplified ingoing RF signals.

3. The integrated circuit radio transceiver of claim 1 wherein the first and second mixers are operably disposed to receive an oscillation of a first polarity during a first mode of operation.

4. The integrated circuit radio transceiver of claim 1 wherein the first and second mixers are operably disposed to receive an oscillation of a second polarity during a second mode of operation.

5. The integrated circuit radio transceiver of claim 1 wherein the third and fourth mixers are operably disposed to receive an oscillation of a first polarity during a first mode of operation.

6. The integrated circuit radio transceiver of claim 1 wherein the third and fourth mixers are operably disposed to receive an oscillation of a second polarity during a second mode of operation.

7. The integrated circuit radio transceiver of claim 1 wherein either the first and second mixers or the third and fourth mixers receive a local oscillation with a first polarity in a first mode of operation and a second polarity in a second mode of operation.

8. The integrated circuit radio transceiver of claim 1 wherein a Balun is multiplexed into a circuit path between an input antenna and the first and second low noise amplifiers during one of a first mode of operation and a second mode of operation.

9. The integrated circuit radio transceiver of claim 8 wherein, while the Balun is multiplexed into the circuit path, either the first and second mixers or the third and fourth mixers receive a local oscillation with polarity that is switched.

10. The integrated circuit radio transceiver of claim 8 wherein, while the Balun is multiplexed into the circuit path, the output of one of the first and third mixers is subtracted from the other.

11. The integrated circuit radio transceiver of claim 8 wherein, while the Balun is multiplexed into the circuit path, the output of one of the second and fourth mixers is subtracted from the other.

12. The integrated circuit radio transceiver of claim 8 wherein the outputs of the first and third mixers are summed and the outputs of the second and fourth mixers are summed.

13. A radio front end, comprising:

a configurable input stage that is operable in a single balanced mode and in a double balanced mode; and

logic for switching between the single balanced mode and the double balanced mode.

14. The radio front end of claim 13 wherein the configurable input stage further includes:

first and second low noise amplifiers operable to produce first and second amplified ingoing RF signals based upon ingoing RF signals;

first and second mixers operably disposed to receive the first amplified ingoing RF signals; and

third and fourth mixers operably disposed to receive the second amplified ingoing RF signals.

15. The radio front end of claim 13 wherein the first and second mixers are operably disposed to receive an oscillation of a first polarity during a first mode of operation.

16. The radio front end of claim 13 wherein the first and second mixers are operably disposed to receive an oscillation of a second polarity during a second mode of operation.

17. The radio front end of claim 13 wherein the third and fourth mixers are operably disposed to receive an oscillation of a first polarity during a first mode of operation.

18. The radio front end of claim 13 wherein the third and fourth mixers are operably disposed to receive an oscillation of a second polarity during a second mode of operation.

19. The radio front end of claim 13 wherein either the first and second mixers or the third and fourth mixers receive a local oscillation with a first polarity in a first mode of operation and a second polarity in a second mode of operation.

20. The radio front end of claim 13 wherein a Balun is multiplexed into a circuit path between an input antenna and the first and second low noise amplifiers during one of a first mode of operation and a second mode of operation.

21. The radio front end of claim 20 wherein, while the Balun is multiplexed into the circuit path, either the first and second mixers or the third and fourth mixers receive a local oscillation with polarity that is switched.

22. The radio front end of claim 20 wherein, while the Balun is multiplexed into the circuit path, the output of one of the first and third mixers is subtracted from the other.

23. The radio front end of claim 20 wherein, while the Balun is multiplexed into the circuit path, the output of one of the second and fourth mixers is subtracted from the other.

24. The radio front end of claim 20 wherein the outputs of the first and third mixers are summed and the outputs of the second and fourth mixers are summed.

25. A method in a radio front end, comprising:

determining whether to operate in a single balanced mode and in a double balanced mode; and

switching between the single balanced mode and the double balanced mode based upon the determining step.

26. The method of claim 25 further including producing first and second amplified ingoing RF signals based upon ingoing RF signals.

27. The method of claim 26 further including receiving the first amplified ingoing RF signals in first and second mixers and receiving the second amplified ingoing RF signals in third and fourth mixers.

28. The method of claim 25 further including receiving an oscillation of a first polarity during a first mode of operation and of a second polarity during a second mode of operation in two of the four mixers in the radio front end.

29. The method of claim 28 wherein a Balun is multiplexed into a circuit path between an input antenna and first and second low noise amplifiers during one of a first mode of operation and a second mode of operation.

30. The method of claim 27 wherein the outputs of the first and third mixers are summed and the outputs of the second and fourth mixers are summed during a first mode of operation and are subtracted during a second mode of operation.

31. The method of claim 30 further including high pass filtering an output of the mixers during at least one of the first and second modes of operation.

32. The method of claim 25 wherein the determining step includes selecting one of a first and second mode of operation based upon a pin selection.

33. The method of claim 25 wherein the determining step includes selecting one of a first and second mode of operation based upon a signal-to-noise ratio of a received radio frequency signal.

34. The method of claim 25 wherein the determining step includes selecting one of a first and second mode of operation based upon whether the receiver is operating with battery power.

35. The method of claim 34 further including operating in a single balanced mode of operation and reducing amplification levels of the first and second low noise amplifiers in relation to amplification levels of the first and second amplifiers while operating in a double balanced mode of operation.

36. A radio front end, comprising:

low noise amplification circuitry operable to produce one either single ended or differential amplified RF signals;

a plurality of singled ended mixers operably disposed to receive the amplified RF signal as single ended or as differential signals; and

one LO polarity block for each mixer and coupled to each mixer, each LO polarity block operably disposed to receive an LO and operable to produce one of a positive or a negative polarity LO to the associated mixer wherein each LO polarity block produces a substantially equal delay to each of the other LO polarity blocks.

37. The radio front end of claim 36 wherein at least one LO polarity block is only operable to introduce processing delay and is not operable to receive a mode command to reverse a polarity of a received LO.