Dual frequency band wireless lan

• US 20030207668A1
• Filed: 05/03/2002
• Published: 11/06/2003
• Est. Priority Date: 05/03/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Atheros Communications Incorporated (Qualcomm, Inc.)
• Inventors: Shor, Arie, McFarland, William J., Terrovitis, Manolis, Zaragari, Masoud, Su, David, Thomson, John, Onedera, Keith
• Granted Patent: US 7,251,459 B2
• Time in Patent Office: Days
• US Class Current: 455/3.01
• CPC Class Codes: H03H 7/0153 Electrical filters; Controlling thereof
• CPC Class Codes: H03H 7/48 Networks for connecting several sources or loads, working on the same frequency or frequency band, to a common load or source phase shifters providing two or more output signals H03H7/21
• CPC Class Codes: H04B 7/0602 using antenna switching H04B7/0686 takes precedence; antenna beam directivity switching H01Q3/24
• CPC Class Codes: H04B 7/0805 with single receiver and antenna switching H04B7/0822 takes precedence
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A dual band radio is constructed using a primary and secondary transceiver. The primary transceiver is a complete radio that is operational in a stand alone configuration. The secondary transceiver is a not a complete radio and is configured to re-use components such as fine gain control and fine frequency stepping of the primary transceiver to produce operational frequencies of the secondary transceiver. The primary transceiver acts like an intermediate frequency device for the secondary transceiver. Switches are utilized to divert signals to/from the primary transceiver from/to the secondary transceiver. The switches are also configured to act as gain control devices. Antennas are selected using either wideband or narrowband antenna switches that are configured as a diode bridge having high impedance at operational frequencies on control lines that bias the diodes.

Claims

1. A wireless LAN device having a dual band RF capability.

2. The wireless LAN device according to claim 1, wherein said dual band capability is implemented via a primary transceiver and a secondary transceiver.

3. The wireless LAN device according to claim 2, wherein the primary transceiver comprises a first RF communication device, and the secondary transceiver comprises a partial RF communication device that utilizes features of the primary transceiver to be able to perform as a second RF communication device.

4. The wireless device according to claim 3, wherein the primary transceiver comprises a fine step frequency control mechanism, and the secondary transceiver comprises a course step frequency control mechanism.

5. The wireless LAN device according to claim 4, wherein the secondary transceiver uses both the coarse frequency steps of the secondary transceiver and the fine frequency steps of the primary transceiver to produce an operational frequency of the secondary transceiver.

6. The wireless LAN device according to claim 3, further comprising:

a fine step frequency control in the primary transceiver;

wherein the secondary transceiver uses a fixed frequency signal and a tuned frequency of the primary transceiver to create an operational frequency signal of the secondary transceiver.

7. The wireless LAN device according to claim 4, wherein said coarse frequency steps comprise frequency steps in a Local Oscillator (LO) of the secondary transceiver of 3.168 GHz and 3.136 GHz.

8. The wireless LAN device according to claim 4, wherein said fine frequency steps comprise frequency steps in a Local Oscillator (LO) of the primary transceiver of 5.58 GHz to 5.64 GHz in 5 MHz steps.

9. The wireless LAN device according to claim 4, wherein said fine frequency steps comprise frequency steps in a Local Oscillator (LO) of the primary transceiver of 5.58 GHz to 5.64 GHz in 5 MHz steps, and 5.620 GHz

10. The wireless LAN device according to claim 4, wherein said fine frequency steps comprise frequency steps in a Local Oscillator (LO) including a set of evenly spaced steps and at least one non-evenly spaced step.

11. The wireless LAN according to claim 10, wherein said at least one non-evenly spaced step is 5.620 GHz.

12. The wireless LAN according to claim 3, wherein transmit gain control of the wireless LAN is performed by the primary transceiver.

13. The wireless LAN according to claim 3, wherein receive gain control of the wireless LAN is performed by the primary transceiver.

14. The wireless device according to claim 3, wherein the primary transceiver comprises a fine step gain control mechanism, and the secondary transceiver comprises a course step gain control mechanism.

15. The wireless LAN device according to claim 14, further comprising a feedback loop that adjusts the fine step gain control based on a signal strength of a signal transmitted from the wireless LAN device.

16. The wireless LAN device according to claim 2, wherein said secondary transceiver comprises a conversion module coupled between the primary transceiver and antennas used by the secondary transceiver.

17. The wireless LAN device according to claim 2, wherein the primary transceiver has a more direct signal path to antennas than the secondary transceiver.

18. The wireless LAN device according to claim 17, wherein the primary transceiver operates at a higher frequency band than the secondary transceiver.

19. The wireless LAN device according to claim 2, wherein the wireless LAN device is fully operational at a frequency range of the primary transceiver when the secondary transceiver is removed from the wireless LAN device.

20. The wireless LAN device according to claim 3, wherein the wireless LAN device is fully operational at a frequency range of the primary transceiver when the secondary transceiver is removed from the wireless LAN device.

21. The wireless LAN device according to claim 3, wherein the primary transceiver is a first integrated chip set and the secondary transceiver is a second integrated chip set, and the wireless LAN device is fully operational at a frequency range of the primary transceiver when the second integrated chip set is removed from the wireless LAN device without any other modifications to the wireless LAN device.

22. The wireless LAN device according to claim 21, wherein transmit gain control is performed in the first integrated chip set.

23. The wireless LAN device according to claim 21, wherein receive gain control is performed in the second integrated chip set.

24. The wireless LAN device according to claim 2, wherein the primary transceiver produces communications signals in a first frequency band, and the secondary transceiver converts the first frequency band communication signals to a second frequency band.

25. The wireless LAN according to claim 24, wherein the conversion performed by the secondary transceiver is less precise than a resolution of the communication signals produced by the primary transceiver.

26. The wireless LAN according to claim 2, wherein operations performed by the secondary transceiver are less precise than operations performed by the primary transceiver.

27. The wireless LAN device according to claim 2, further comprising a band selection switch configured to route signals to/from the primary transceiver from/to one of at least one antenna and the secondary transceiver.

28. The wireless LAN device according to claim 27, wherein the band selection switch comprises a three position switch wherein the first position implements a connection between the primary transceiver and a said at least one antenna, the second position implements a connection between the primary transceiver and the secondary transceiver, and the third position is a neutral open circuit position.

29. The wireless LAN device according to claim 28, wherein the third neutral open circuit position allows signals to leak from one of said at least one antenna and the secondary transceiver to the primary transceiver when the wireless LAN device is receiving signals.

30. The wireless LAN device according to claim 29, further comprising a control device configured to set the three position switch to, the first position when the wireless LAN device is transmitting or receiving on the frequency band of the primary transmitter, the second position when the wireless LAN device is transmitting or receiving on the frequency band of the secondary transmitter, and the third position when incoming signals being received are too large for proper processing in the primary transceiver.

31. The wireless LAN device according to claim 29, further comprising a control device configured to set the three position switch to the third position when incoming signals being received need to be reduced in signal size for proper processing in the primary transceiver.

32. The wireless LAN device according to claim 29, further comprising a control device configured to set the three position switch to the third position when incoming signals being received would otherwise saturate at least one component of the primary transceiver.

33. The wireless device according to claim 32, wherein said at least one component is an Analog to Digital Conversion (ADC) device in a baseband portion of the primary transceiver.

34. The wireless device according to claim 29, wherein the third switch position operates as a signal attenuation device.

35. The wireless LAN device according to claim 29, wherein the switch is chosen so that the amount of leakage comprises a 5-15 dB received signal strength reduction at the primary transceiver.

36. The wireless LAN device according to claim 29, further comprising a control device configured to set the three position switch to the second position when incoming signals being received on a frequency band of the primary transceiver would otherwise saturate at least one component of the primary transceiver.

37. The wireless LAN device according to claim 29, further comprising a control device configured to set position 3 if an incoming signal is in a first predetermined signal strength range, and set position 2 if an incoming signal is within a second predetermined signal strength range, said first and second predetermined signal strength ranges are selected so that the incoming signal, after signal attenuation from the switch position and any other attenuation in the signal path, is properly sized for receiving components of the primary transceiver.

38. The wireless LAN device according to claim 37, wherein said receiving components include at least an Analog to Digital Converter (ADC).

39. The wireless LAN device according to claim 2, wherein said primary and secondary transceivers operate at frequencies disparate enough so that off-chip filtering is not required.

40. The wireless LAN device according to claim 2, wherein said primary and secondary transceivers are implemented in chip sets having enough on chip filtering such that no signal interference occurs between different frequency bands of the primary and secondary transceiver.

41. The wireless LAN device according to claim 3, wherein each of the primary and second transceivers have a Local Oscillator for producing mixing frequencies for production of operational frequencies of each respective transceiver.

42. The wireless LAN device according to claim 41, wherein the primary transceiver LO and the secondary transceiver LO share a same reference frequency.

43. The wireless LAN device according to claim 42, wherein said reference frequency is 32 MHz.

44. The wireless LAN device according to claim 43, wherein the mixing frequencies of the primary LO comprises 5.58 GHz to 5.64 GHz in 5 MHz steps, and at least one out-of-step frequency.

45. The wireless LAN device according to claim 44, wherein the out of step frequency is 5.62 GHz.

46. The wireless LAN according to claim 42, wherein the mixing frequencies of the secondary LO comprises 3.168 GHz and a set of at least one course step frequency.

47. The wireless LAN according to claim 46, wherein said at least one course step frequency is 3.136 GHz.

48. The wireless LAN device according to claim 3, further comprising:

a transmit switch coupled to an RF output of the primary transceiver and configured to route signals from the primary transceiver to one of an IF input of the secondary transceiver and a front end of the wireless LAN device; and

a receive switch coupled to an RF input of the primary transceiver and configured to route signals from one of an IF output of the secondary transceiver and a front end of the primary transceiver to an RF input of the primary transceiver.

49. The wireless LAN device according to claim 48, wherein said front end comprises a primary power amplifier for amplification of signals for transmission directly from the primary transceiver, a primary low noise amplifier for reception of signals to be directly received by the primary transceiver, a secondary power amplifier for amplification of signals for transmission from the secondary transceiver, and a secondary low noise amplifier for amplification of reception signals to be received by the secondary transceiver.

50. The wireless LAN device according to claim 49, further comprising:

a control device configured to produce one of Tx primary, Rx primary, Tx secondary and Rx secondary control signals;

wherein the produced control signal enables the front end amplifier corresponding to the control signal, and, sets at least one of the transmit and receive switches to make an appropriate signal path from the enabled amplifier to one of the primary and secondary transceivers.

51. The wireless LAN device according to claim 50, wherein said control device is programmable as to timing of the Rx and Tx control signals.

52. The wireless LAN device according to claim 50, wherein said control device is programmable as to a polarity of the Rx and Tx control signals.

53. The wireless LAN device according to claim 3, further comprising at least two antennas, and an antenna switch configured to select at least one of the antennas to operate with a currently active one of the primary and secondary transceiver.

54. The wireless LAN device according to claim 53, wherein the antenna switch comprises a diode bridge switch having control feeds with high impedance at operational frequencies of both the primary and secondary transceivers.

55. The wireless LAN device according to claim 54, wherein said high impedance frequencies are the 2.4 GHz frequency band, and the 5 GHz frequency band.

56. The wireless LAN device according to claim 54, wherein at least one of the control feeds is an inductor and a printed transmission line.

57. The wireless LAN device according to claim 54, wherein at least one of the control feeds is two series inductors.

58. The wireless LAN device according to claim 53, wherein said antennas are dual band antennas.

59. The wireless LAN device according to claim 58, wherein said dual band antennas are configured to operate in the 2.4 GHz and 5 GHz frequency bands.

60. The wireless LAN device according to claim 53, wherein said antenna switch is a user configurable matrix. [Please review—

user configurable matrix]

61. The wireless LAN device according to claim 53, further comprising a tunable Hi/Lo filter coupled between the antennas and a front end of the primary transceiver.

62. The wireless LAN device according to claim 61, further comprising a control device that recognizes a channel currently tuned to by the primary transceiver and sends a signal to the tunable Hi/Lo filter to tune it to a pass band such that the channel of the primary transceiver is passed by the tunable filter.

63. The wireless device according to claim 62, wherein said tunable filter is a filter having an adjustable capacitance value that tunes the pass band of the filter.

64. The wireless LAN device according to claim 63, wherein the adjustable capacitance comprises a set of at least two parallel capacitors, at least one of said capacitors being isolated from the tunable filter via a switchable diode.

65. The wireless LAN device according to claim 64, wherein the switchable diode comprises a control voltage isolated from HF signals and configured to bias the diode so that the isolated capacitor becomes part of the filter tuning.

66. The wireless device according to claim 65, wherein said control voltage isolation is performed via an RF choke.

67. The wireless device according to claim 62, wherein said control device is user programmable as to a switching point between high and low settings of the Hi/Lo tunable filter.

68. The wireless LAN device according to claim 67, wherein said switching point is a frequency between bands within an overall frequency range of the primary transceiver.

69. The wireless LAN device according to claim 67, wherein said switching point is above 2.4 GHz and below 5 GHz [5.15-5.8?].

70. The wireless LAN device according to claim 3, further comprising a primary transceiver transmit signal strength detector and a secondary transmit signal strength detector;

a signal strength adjustment mechanism configured to adjust transmission power of the primary transceiver based on the transmit signal strength detected.

72. The wireless LAN device according to claim 3, wherein the wireless LAN device operates without diplexers.

73. The wireless LAN device according to claim 3, further comprising:

an antenna port having an antenna switch configured to select at least one of a set of diversity antennas;

a primary Tx/Rx switch having a first switch position configured to connect signals transmitted from the primary transceiver to the antenna port and a second switch position connect signals received from the antenna port to the primary transceiver;

a secondary Tx/Rx switch having a first switch position configured to connect signals transmitted from the secondary transceiver to the antenna port and a second switch position connect signals received from the antenna port to the secondary transceiver.

74. The wireless LAN device according to claim 73, further comprising a control device configured to identify a frequency F_RX of a signal being transmitted or received by the wireless LAN device and set the antenna switch and Tx/Rx switches so that a signal path corresponding to F_RX and the Tx/Rx nature of the signal being transmitted or received.

75. The wireless LAN device according to claim 53, wherein the antenna switch comprises a diode bridge switch having control feeds with high impedance at frequency bands utilized by both of the primary and secondary transceivers.

76. The wireless LAN device according to claim 54, wherein said high impedance frequencies are the 2.4 GHz frequency band, and the 5 GHz frequency band.

77. The wireless LAN device according to claim 75, wherein at least one of the control feeds is an inductor and a printed transmission line.

78. The wireless LAN device according to claim 75, wherein at least one of the control feeds is two series inductors.

79. The wireless LAN device according to claim 3, wherein the wireless LAN device operates with a fewest number of switches in transmit and receive chains of at least one of the transceivers.

80. The wireless device according to claim 79, further comprising:

an antenna port having an antenna switch configured to select at least one of a set of diversity antennas;

a combinatorial diplexer coupled to the antenna port and configured to collect transmitted signals from the primary transceiver and transmitted signal from the secondary transceiver and forward the collected signals to the antenna port;

a splitting diplexer coupled to the antenna port and configured to split signals received by the antenna port based on frequency into a first set of signal frequencies that are forwarded to the primary transceiver and a second set of signal frequencies forwarded to the secondary transceiver.

81. The wireless LAN device according to claim 80, wherein the antenna switch comprises a diode bridge switch having control feeds with high impedance at frequency bands utilized by both the primary and secondary transceivers.

82. The wireless LAN device according to claim 81, wherein said high impedance frequencies are the 2.4 GHz frequency band and the 5 GHz frequency band.

83. The wireless LAN device according to claim 81, wherein at least one of the control feeds is an inductor and a printed transmission line.

84. The wireless LAN device according to claim 81, wherein at least one of the control feeds is a set of series inductors.

85. The wireless LAN device according to claim 3, wherein the wireless LAN device is constructed without any wideband switches.

86. The wireless device according to claim 79, further comprising:

at least two antenna ports;

a diplexer coupled to each antenna port;

wherein each diplexer is configured to split a first band of signals received from the antenna port onto a first band line, split a second band of signals received from the antenna port onto a second band line, and retrieve transmitted signals on either of the first and second band lines and forward them to the antenna port.

87. The wireless LAN device according to claim 86, further comprising:

a primary single band switch configured to connect one of the first band lines from the diplexers to one of a transmit and receive part of the primary transceiver; and

a secondary single band switch configured to connect one of the second band lines from the diplexers to one of a transmit and receive part of the secondary transceiver.

88. The wireless LAN device according to claim 87, wherein each single band switch comprises a diode bridge switch having control feeds with high impedance at the single band frequency of the connected transceiver.

89. The wireless LAN device according to claim 87, wherein the transmit and receive parts of the primary transceiver comprise a Power Amplifier (PA) and a Low Noise Amplifier (LNA) of a front end of the primary transceiver.

90. The wireless LAN device according to claim 87, wherein the transmit and receive parts of the secondary transceiver comprise a Power Amplifier (PA) and a Low Noise Amplifier (LNA) of a front end of the secondary transceiver.

91. The wireless LAN device according to claim 3, wherein w said wireless LAN device is constructed to be used with a set of single band diversity antennas.

92. The wireless LAN device according to claim 3, further comprising:

a primary antenna port having connections for at least two antennas;

an antenna switch connected to the primary antenna port and configured to connect one of the antenna connections to a primary band line coupled to the primary transceiver.

93. The wireless LAN device according to claim 92, further comprising a Tx/Rx switch configured to direct the primary band line to one of a PA device of the primary transceiver and an LNA device of the primary transceiver.

94. The wireless LAN device according to claim 3, further comprising:

a secondary antenna port having connections for at least two antennas;

an antenna switch connected to the secondary antenna port and configured to connect one of the antenna connections to a secondary band line coupled to the secondary transceiver.

95. The wireless LAN device according to claim 94, further comprising a secondary Tx/Rx switch configured to direct the secondary band line to one of a PA device of the secondary transceiver and an LNA device of the secondary transceiver.

71. The wireless LAN device according 70, further comprising a detection selection switch configured select the primary signal strength detector for detecting transmit signal strength when the primary transceiver is transmitting and select the secondary signal strength detector for detecting transmit signal power when the secondary transceiver is transmitting.

96. A dual band capable wireless device, comprising:

a primary transceiver configured to operate in a primary frequency band; and

a set of hardware connections configured to accept a secondary transceiver that one of converts signals emanating from the primary transceiver to a second frequency band, and converts received signals of the second frequency band to the primary frequency band and forwards the converted primary frequency band signals to the primary transceiver.

97. The dual band capable wireless device according to claim 96, further comprising a control device configured to assert control signals configured to initiate switching functions that route signals to and from the set of hardware connections when the dual band capable wireless device is operating in the second frequency band.

98. The dual band capable wireless device according to claim 97, wherein said hardware connections comprise a set of I/O ports connected to transmit and receive lines of the primary transceiver.

99. The dual band capable wireless device according to claim 98, wherein said hardware connections include a set of ports that carry said control signals.

100. A method of performing wireless LAN (WLAN) communications with a dual band WLAN device, comprising the steps of:

listening for primary communication signals in a primary frequency band;

initiating WLAN operations in the primary frequency band if a wireless LAN is detected in the primary frequency band.

101. The method according to claim 100, further comprising the steps of:

listening for secondary communication signals in a secondary frequency band if primary communication signals are not detected in the primary frequency band; and

initiating WLAN operations in the secondary frequency band if a wireless LAN is detected in the secondary frequency band.

102. The method according to claim 101, further comprising the step of repeating the steps of listening and initiating if no WLAN operations have been initiated or if previously established WLAN operations have ceased.

103. The method according to claim 102, wherein said repeated steps are performed at a predetermined interval.

104. The method according to claim 101, wherein said step of initiating WLAN operations in the secondary frequency band comprises outputting a communication message from a primary transceiver at the primary frequency to a secondary transceiver that converts the primary frequency to the secondary frequency and then broadcast the communication.

105. The method according to claim 104, wherein the primary communication device performs all fine gain and frequency adjustments for the broadcast secondary frequency communication.

106. The method according to claim 101, wherein said step of initiating WLAN operations in the secondary frequency band comprises the steps of:

receiving a communication message at the secondary frequency band;

converting the secondary frequency band communication message to the primary frequency band; and

processing the converted communication message in the primary transceiver.

107. The method according to claim 106, wherein switches directing flow of the received and converted received communication are utilized to properly size the incoming communication so as not to saturate any components of the primary transceiver.

108. The method according to claim 107, wherein said switches are set to a position not directly connecting a signal path of the incoming communication so that leakage onto the signal path provides an attenuated signal to the signal path.

109. The method according to claim 100, wherein:

said method is embodied in a set of computer instructions stored on a computer readable media;

said computer instructions, when loaded into a computer, cause the computer to perform the steps of said method.

110. The method according to claim 109, wherein said computer instructions are compiled computer instructions stored as an executable program on said computer readable media.

111. The method according to claim 100, wherein said method is embodied in a set of computer readable instructions stored in an electronic signal.