Multiple-Input Multiple-Output Radio Transceiver

• US 20030203743A1
• Filed: 10/11/2002
• Published: 10/30/2003
• Est. Priority Date: 04/22/2002
• Status: Active Grant

• Current Assignee: Cognio, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cognio, Inc. (Cisco Systems, Inc.)
• Inventors: Masucci, Robert M., Rahn, David G., Sugar, Gary L.
• Granted Patent: US 6,728,517 B2
• Time in Patent Office: Days
• US Class Current: 455/550.1
• CPC Class Codes: H03D 2200/0025 Gain control circuits
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• 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 1/0057 using diplexing or multiplexing filters for selecting the desired band
• 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

Abstract of Disclosure

A MIMO radio transceiver to support processing of multiple signals for simultaneous transmission via corresponding ones of a plurality of antennas and to support receive processing of multiple signals detected by corresponding ones of the plurality of antennas. The radio transceiver provides, on a single semiconductor integrated circuit, a receiver circuit or path for each of a plurality of antennas and a transmit circuit or path for each of the plurality of antennas. Each receiver circuit downconverts the RF signal detected by its associated antenna to a baseband signal. Similarly, each transmit path upconverts a baseband signal to be transmitted by an assigned antenna.

Claims

1. A multiple-input multiple-output (MIMO) radio transceiver comprising:

2. The radio transceiver of claim 1, wherein the first receive signal detected by the first antenna and the second receive signal detected by the second antenna are components of a single signal to be processed by the radio transceiver, and wherein the first receiver circuit and the second receiver circuit process the first and second receive signals substantially simultaneously to allow for combining of signals resulting from processing by the first and second receiver circuits.

3. The radio transceiver of claim 1, wherein the first analog baseband signal and the second analog baseband signal are weighted components of a single signal, and wherein the first transmitter circuit and the second transmitter circuit process the first and second analog baseband signals for transmission substantially simultaneously.

4. The radio transceiver of claim 1, and further comprising a frequency synthesizer that produces an RF local oscillator signal that is coupled to each of the first and second downconverters to be mixed with the first and second receive signals, respectively, wherein the RF local oscillator signal may be at any frequency within one or more discrete radio frequency bands.

5. The radio transceiver of claim 4, wherein the frequency synthesizer couples the RF local oscillator signal to the first and second upconverters to up-mix the first and second baseband analog signals, respectively.

6. The radio transceiver of claim 1, wherein the first and second receiver circuits and the first and second transmitter circuits are implemented on a single semiconductor integrated circuit.

7. The radio transceiver of claim 1, wherein the first receiver circuit further comprises a first sample-and-hold circuit coupled to the output of the first lowpass filter and the second receiver circuit further comprises a second sample-and-hold circuit coupled to the output of the second lowpass filter.

10. The radio transceiver of claim 1, wherein the first and second downconverters comprise a two stage mixing process to downconvert the first and second receive signals to first and second intermediate frequency signals at a common intermediate frequency, and then to first and second baseband signals.

11. The radio transceiver of claim 1, wherein the first lowpass filter of the first receiver circuit and the second lowpass filter of the second receiver circuit are variable lowpass filters that are responsive to a bandwidth control signal so as to pass a portion of a radio frequency band or substantially the entire radio frequency band.

12. The radio transceiver of claim 1, wherein the first upconverter and the second upconverter comprise first and second lowpass filters to filter the first and second baseband analog signals, respectively, prior to upconversion, wherein the first and second lowpass filters are variable lowpass filters that are responsive to a bandwidth control signal so as to filter the first and second baseband analog signals for transmission in a portion of the radio frequency band, or in substantially the entire radio frequency band.

13. The radio transceiver of claim 1, wherein the first downconverter comprises first and second RF mixers, wherein the first RF mixer down-mixes the first receive signal to an intermediate frequency signal when the first receive signal is in a first radio frequency band and the second RF mixer down-mixes the first receive signal to an intermediate frequency signal when the first receive signal is in a second radio frequency band, and wherein the second downconverter comprises first and second RF mixers, wherein the first RF mixer down-mixes the second receive signal to an intermediate frequency signal when the second receive signal is in a first radio frequency band and the second RF mixer down-mixes the second receive signal to an intermediate frequency signal when the second receive signal is in the second radio frequency band.

8. The radio transceiver of claim1, wherein the first and second downconverters comprise a single stage mixing process to downconvert the first and second receive signals directly to baseband.

9. The radio transceiver of claim 8, and further comprising a frequency synthesizer that supplies an RF local oscillator signal to the first and second downconverters, wherein an IF local oscillator signal is derived from the RF local oscillator signal that is also supplied to the first and second downconverters.

14. A multiple-input multiple-output (MIMO) radio transceiver comprising:

15. The radio transceiver of claim 14, wherein the first downconverter comprises first and second RF mixers, wherein the first RF mixer down-mixes the first receive signal to an intermediate frequency signal when the first receive signal is in a first radio frequency band and the second RF mixer down-mixes the first receive signal to an intermediate frequency signal when the first receive signal is in a second radio frequency band, and wherein the second downconverter comprises first and second RF mixers, wherein the first RF mixer down-mixes the second receive signal to an intermediate frequency signal when the second receive signal is in a first radio frequency band and the second RF mixer down-mixes the second receive signal to an intermediate frequency signal when the second receive signal is in the second radio frequency band.

16. The radio transceiver of claim 15, wherein the first downconverter further comprises a pair of quad mixers coupled to the output of the first and second RF mixers to further down-mix the intermediate frequency signal to the first in-phase and quadrature baseband signals representative of the first receive signal, and the second downconverter further comprises a pair of quad mixers coupled to the output of the first and second RF mixers to further down-mix the intermediate frequency signal to the second in-phase and quadrature baseband signals representative of the second receive signal.

17. The radio transceiver of claim 16, and further comprising an RF frequency synthesizer that generates an RF local oscillator signal for the RF mixers in the first and second downconverters and wherein an intermediate frequency local oscillator signal used by the quad mixers in the first and second downconverters is derived from the RF mixing signal.

18. The radio transceiver of claim 17, and further comprising a divide-by-four circuit coupled to the RF frequency synthesizer that divides the frequency of the RF local oscillator signal to generate the intermediate frequency local oscillator signal that is coupled to the quad mixers in the first and second downconverters.

19. The radio transceiver of claim 16, and further comprising an RF frequency synthesizer that generates an RF local oscillator signal for the RF mixers and an intermediate frequency synthesizer that generates an intermediate frequency local oscillator signal for the quad mixers in the first and second downconverters.

20. The radio transceiver of claim 14, wherein the first downconverter comprises a pair of quad mixers that down-mix the first receive signal directly to the first in-phase and quadrature baseband signals, and the second downconverter comprises a pair of quad mixers that down-mix the second receive signal directly to the second in-phase and quadrature baseband signals.

21. The radio transceiver of claim 20, wherein the first and second receiver circuits each further comprise a variable amplifier coupled to amplify the intermediate frequency signal before it is supplied to their quad mixers.

22. The radio transceiver of claim 14, wherein the first upconverter comprises a pair of quad mixers that up-mix the first baseband in-phase and quadrature signals to an intermediate frequency signal, the second upconverter comprises a pair of quad mixers that up-mix the second baseband in-phase and quadrature signals to an intermediate frequency signal.

23. The radio transceiver of claim 21, wherein the first upconverter further comprises an RF mixer coupled to the output of the quad mixers that up-mixes the intermediate frequency signal to a first RF signal, and the second upconverter further comprises an RF mixer coupled to the output of the quad mixers that up-mixes the intermediate frequency signal to a second RF signal.

24. The radio transceiver of claim 23, wherein the first and second transmitter circuits each further comprises a variable amplifier coupled to amplify the intermediate frequency signal before it is supplied to their RF mixers.

25. The radio transceiver of claim 23, wherein the first and second transmitter circuits further comprise first and second bandpass filters coupled to the output of their RF mixers, that are dedicated to bandpass filtering signals to be transmitted in a first radio frequency band, and third and fourth bandpass filters coupled to the RF mixers to filter signals to be transmitted in a second radio frequency band.

26. The radio transceiver of claim 14, wherein the first receiver circuit comprises first and second sample-and-hold circuits that are connected to the first and second lowpass filters, respectively, to couple the first in-phase baseband signal and the first quadrature-phase baseband signal to an analog-to-digital converter, and the second receiver circuit comprises third and fourth sample-and-hold circuits that are connected to the third and fourth lowpass filters, respectively, to couple the second in-phase baseband signal and the second quadrature-phase baseband signal to an analog-to-digital converter.

27. The radio transceiver of claim 14, wherein the receiver and the transmitter are implemented on a single semiconductor integrated circuit.

28. The radio transceiver of claim 14, wherein the first receive signal detected by the first antenna and the second receive signal detected by the second antenna are components of a single signal to be processed by the radio transceiver, and wherein the first receiver circuit and the second receiver circuit process the first and second signals substantially simultaneously to allow for combining of signals resulting from processing by the first and second receiver circuits.

29. The radio transceiver of claim 14, wherein the first analog baseband signal and the second analog baseband signal are weighted components of a single signal, and wherein the first transmitter circuit and the second transmitter circuit process the first and second analog baseband signals for transmission substantially simultaneously.

30. The radio transceiver of claim 14, wherein the first, second, third and fourth lowpass filters are variable lowpass filters that are responsive to a bandwidth control signal so as to pass a portion of a radio frequency band or to pass substantially the entire radio frequency band.

31. The radio transceiver of claim 30, wherein the first and second variable lowpass filters receive as input the first in-phase baseband analog signal and the first quadrature phase baseband analog signal, respectively, and the third and fourth lowpass filters receive as input the second in-phase baseband analog signal and the second quadrature-phase baseband analog signal, respectively, to filter these signals for transmission in a portion of the radio frequency band, or in substantially the entire radio frequency band.

32. The radio transceiver of claim 14, wherein the first transmitter circuit comprises first and second variable lowpass filters to filter the first in-phase and quadrature-phase signals prior to upconversion and the second transmitter circuit comprises third and fourth variable lowpass filters to filter the second in-phase and quadrature-phase signals prior to upconversion, wherein the first, second, third and fourth variable lowpass filters in the first and second transmitter circuits are variable lowpass filters that are responsive to a bandwidth control signal so as to filter the first and second baseband analog signals for transmission in a portion of the radio frequency band, or in substantially the entire radio frequency band.

33. The radio transceiver of claim 14, wherein the first downconverter and the second downconverter downconvert the first and second receive signals, respectively, directly to baseband in a single stage downconversion process.

34. In combination, the radio transceiver of claim 14, and further comprising:

35. The combination of claim 34, and further comprising a first switch having first and second input terminals and an output terminal, the output terminal of the first switch being coupled to the input of the ADC, the first and input terminals of the first switch being coupled to any two signals of:

the analog transmit power level signal, first or second quadrature baseband analog signal, and the first or second in-phase baseband analog signal, and a second switch having first and second output terminals and an input terminal, the input terminal of the second switch being coupled to the output of the DAC, and wherein the digital multiplexer directs one of the following signals to the input of the DAC;

the first or second digital quadrature-phase transmit signal, first or second digital in-phase transmit signal, and the digital receiver gain control signal.

36. In combination, the radio transceiver of claim 14, and a front-end section comprising:

37. The combination of claim 36, wherein the first and second bandpass filters are dedicated to filtering signals in a first radio frequency band, and further comprising:

38. The combination of claim 37, wherein the radio front-end section further comprises third and fourth band select switches, each having first and second input terminals, and an output terminal, the output terminal of the third and fourth band select switches being coupled to the transmit input terminals of the first and second transmit/receive switches.

39. The combination of claim 38, wherein the radio front-end section further comprises first and second lowpass filters dedicated to filtering signals to be transmitted in the first radio frequency band, the outputs of the first and second lowpass filters being connected to the first input terminals of the third and fourth band select switches, respectively, and third and fourth lowpass filters dedicated to filtering signals to be transmitted in the second radio frequency band, the outputs of the third and fourth lowpass filters being connected to the second input terminals of the third and fourth band select switches.

40. In combination, the radio transceiver of claim 14, and a radio front-end section, wherein the radio-front end section comprises a first diplexer to be coupled to the first antenna and a second diplexer to be coupled to the second antenna, wherein the first and second diplexers each have first and second branches onto which signals from first and second radio frequency bands, respectively, are coupled for transmission via the first and second antennas, respectively, or are coupled when received by the first and second antennas, respectively.

41. The combination of claim 40, wherein for each diplexer, the radio front-end section further comprises a bandpass filter coupled in the first branch to filter signals received in the first frequency band and a bandpass filter coupled in the second branch to filter signals received in the second frequency band.

42. The combination of claim 41, wherein the radio-front end section further comprises a transmit/receive switch coupled to the bandpass filter in each of the first and second branches for each diplexer, wherein the transmit/receive switch selects either a signal to be transmitted through an antenna coupled to the associated diplexer, or a signal detected by an antenna coupled to the associated diplexer which is coupled to the bandpass filter for that branch.

43. The combination of claim 41, wherein the radio transceiver further comprises a transmit/receive switch coupled to the bandpass filter in each of the first and second branches for each diplexer, wherein the transmit/receive switch selects either a signal to be transmitted through an antenna coupled to the associated diplexer, or a signal detected by an antenna coupled to the associated diplexer which is coupled to the bandpass filter for that branch.

44. The combination of claim 43, wherein the radio front-end section further comprises a quarter wavelength element coupled between the transmit/receive switch and the bandpass filter in each of the first and second branches for each diplexer.

45. A multiple-input multiple-output (MIMO) radio transceiver on a single semiconductor integrated circuit, comprising:

46. The radio transceiver of claim 45, wherein the first receive signal detected by the first antenna and the second receive signal detected by the second antenna are components of a single signal to be processed by the radio transceiver, and wherein the first receiver circuit and the second receiver circuit process the first and second receive signals substantially simultaneously to allow for combining of signals resulting from processing by the first and second receiver circuits.

47. The radio transceiver of claim 45, wherein the first analog baseband signal and the second analog baseband signal are weighted components of a single signal, and wherein the first transmitter circuit and the second transmitter circuit process the first and second analog baseband signals for transmission substantially simultaneously.

48. The radio transceiver of claim 45, and further comprising a frequency synthesizer that produces an RF local oscillator signal that is coupled to each of the first and second downconverters to be mixed with the first and second receive signals, respectively, wherein the RF local oscillator signal may be at any frequency within one or more discrete radio frequency bands.

49. The radio transceiver of claim 48, wherein the frequency synthesizer couples the RF local oscillator signal to the first and second upconverters to upmix the first and second baseband analog signals, respectively.

50. The radio transceiver of claim 45, wherein the first and second downconverters comprise a single stage mixing process to downconvert the first and second receive signals directly to baseband.

51. The radio transceiver of claim 50, wherein the first downconverter comprises a pair of quad mixers that down-mix the first receive signal directly to first in-phase and quadrature baseband signals, and the second downconverter comprises a pair of quad mixers that down-mix the second receive signal directly to the second in-phase and quadrature baseband signals.

52. The radio transceiver of claim 45, wherein the first lowpass filter of the first receiver circuit and the second lowpass filter of the second receiver circuit are variable lowpass filters that are responsive to a bandwidth control signal so as to pass a portion of a radio frequency band or substantially the entire radio frequency band.

53. The radio transceiver of claim 45, wherein the first upconverter and the second upconverter comprise first and second lowpass filters to filter the first and second baseband analog signals, respectively, prior to upconversion, wherein the first and second lowpass filters are variable lowpass filters that are responsive to a bandwidth control signal so as to filter the first and second baseband analog signals for transmission in a portion of the radio frequency band, or in substantially the entire radio frequency band.