METHODS, SYSTEMS, AND NON-TRANSITORY COMPUTER READABLE MEDIA FOR WIDEBAND FREQUENCY AND BANDWIDTH TUNABLE FILTERING

• US 20130225099A1
• Filed: 01/18/2013
• Published: 08/29/2013
• Est. Priority Date: 08/30/2010
• Status: Active Grant

• Current Assignee: Physical Devices, LLC
• Original Assignee: Physical Devices, LLC
• Inventors: Vosburgh, Frederick, Wilkerson, Jonathan Ryan, Wilson, Charley Theodore III
• Granted Patent: US 9,042,857 B2
• Time in Patent Office: Days
• US Class Current: 455/78
• CPC Class Codes: H04B 1/1018 noise filters connected between the power supply and the receiver suppression or limitation of noise from electric apparatus H04B15/00; demodulation H03D; ripple filters H02M1/14; filters in general 95G, H03H; power supplies H04B1/1607
• CPC Class Codes: H04B 1/1081 Reduction of multipath noise by equalising H04B7/005
• CPC Class Codes: H04B 1/44 Transmit/receive switching
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 7/0894 using different delays between antennas

Abstract

Methods, systems, and computer readable media for wideband frequency and bandwidth tunable filtering are disclosed. According to one aspect, the subject matter described herein includes a wideband frequency and bandwidth tunable filter that splits a filter input signal into first and second input signals, modifies the first input signal to produce a first output signal, modifies the second input signal to produce a second output signal having an intermediate frequency response, and combines the first and second output signals while adjusting their relative phases and/or amplitudes to produce a filter output signal with the target frequency response. Adjustment includes splitting the second input signal into third and fourth input signals, which are modified and then combined to produce the second output signal having the intermediate frequency response.

Claims

1. A wideband frequency and bandwidth tunable filter, comprising:

a first splitter for receiving a filter input signal and producing a first input signal and a second input signal;

a first modifier block for modifying the first input signal to produce a first output signal;

an adjustment circuit for modifying the second input signal to produce a second output signal having an intermediate frequency response;

a first signal combiner for combining the first output signal and the second output signal to produce a filter output signal; and

a compensation device for adjusting at least one of a phase of the first output signal relative to a phase of the second output signal and an amplitude of the first output signal relative to an amplitude of the second output signal such that the filter output signal has a desired frequency response,

wherein the adjustment circuit comprises;

a second splitter for receiving the second input signal and producing a third input signal and a fourth input signal;

a second modifier block for modifying the third input signal to produce a third output signal;

a third modifier block for modifying the fourth input signal to produce a fourth output signal; and

a second signal combiner for combining the third output signal and the fourth output signal to produce the second output signal having the intermediate frequency response.

6. The tunable filter of claim 1, comprising a conditioning circuit for conditioning at least one of the third input signal and the fourth input signal.

7. The tunable filter of claim 6 wherein the conditioning circuit includes a saturation circuit for at least partially saturating an input to the conditioning circuit with respect to at least one target frequency.

16. The tunable filter of claim 1 wherein the compensation device adjusts a phase of the first output signal relative to a phase of the second output signal according to a feed-forward method.

17. The tunable filter of claim 1 wherein the compensation device adjusts a phase of the first output signal relative to a phase of the second output signal by performing a deterministic algorithm.

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21. A receiver with tunable filter, the receiver comprising:

an interface for receiving at least one input signal; and

a wideband frequency and bandwidth tunable filter for filtering the at least one input signal and producing a filtered output signal having a desired frequency response, the filter including a filter input node for receiving the at least one input signal from the interface, the filter comprising;

a first signal path for receiving a first filter input signal from the filter input node and producing a first filter output signal;

a second signal path for receiving a second filter input signal from the filter input node and producing a second filter output signal, the second signal path including an adjustment circuit for adjusting the frequency spectrum of the second filter input signal to produce the second filter output signal;

a conditioning circuit for conditioning at least one of the first filter input signal and the second filter input signal to provide at least one conditioned input signal to the adjustment circuit;

a compensation device for adjusting at least one of a phase of the first filter output signal relative to a phase of the second filter output signal and an amplitude of the first filter output signal relative to an amplitude of the second filter output signal; and

a signal combiner for combining the first filter output signal with the second filter output signal to produce the filtered output signal having a desired frequency spectrum.

27. The receiver of claim 21 wherein the conditioning circuit includes a saturation circuit for at least partially saturating an input to the conditioning circuit with respect to a target frequency.

28. The receiver of claim 27 wherein the saturation circuit at least partially saturates the second filter input signal to provide at least one conditioned second input signal to the adjustment circuit.

29. The receiver of claim 27 wherein the saturation circuit at least partially saturates a third signal provided by a signal generation circuit and combines the at least partially saturated third signal with the second filter input signal to provide at least one conditioned second input signal to the adjustment circuit.

36. The receiver of claim 21 wherein the compensation device adjusts a phase of the first filter output signal relative to a phase of the second filter output signal according to a feed-forward method.

37. The receiver of claim 21 wherein the compensation device adjusts a phase of the first filter output signal relative to a phase of the second filter output signal by performing a deterministic algorithm.

41. The receiver of claim 21 wherein the interface receives the at least one input signal from a single antenna.

47. The receiver of claim 21 further comprising

an input for receiving data to be transmitted Tx;

and

a first antenna for receiving a received signal Rx that contains both a desired signal S and transmit interference Tx′

;

wherein received signal Rx is provided to the first signal path of the filter, wherein data to be transmitted Tx is provided to the second signal path of the filter, wherein the filter reduces the presence of transmit interference Tx′

in the filtered output signal, which contains S.

48. The receiver of claim 47 wherein data to be transmitted Tx is provided to the first antenna and wherein transmit interference Tx′

comprises signal reflections within the first antenna.

52. The receiver of claim 47 wherein data to be transmitted Tx is provided to a second antenna and wherein the transmit interference Tx′

comprises interference from the second antenna.

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55. A method for wideband frequency and bandwidth tunable filtering, the method comprising:

receiving an input signal for which wideband frequency and bandwidth tunable filtering is desired;

creating a second input signal having at least one of a desired phase, amplitude, and delay relative to the first input signal;

modifying the second input signal to create a modified second input signal having a desired frequency spectrum, wherein creating the modified second input signal having the desired frequency spectrum includes creating a third input signal having at least one of a desired phase, amplitude, and delay relative to the second input signal, modifying the third input signal to produce a fourth input signal, and combining the second input signal and the fourth input signal to create the modified second input signal having the desired frequency spectrum;

adjusting at least one of phase, delay, amplitude magnitude, amplitude sign, and frequency spectrum of the modified second input signal with respect to the first input signal; and

combining the modified second input signal with the first input signal to create an output signal having the desired frequency response.

56. The method of claim 55 wherein modifying the second input signal to create a modified second input signal having a desired frequency spectrum comprises creating a modified second input signal having at least one of a passband frequency response and a null passband frequency response.

57. The method of claim 55 wherein modifying the second input signal to create a modified second input signal having a desired frequency spectrum comprises adjusting at least one of a target center frequency and a target bandwidth of the desired frequency spectrum.

58. The method of claim 55 wherein creating the modified second signal having the desired frequency spectrum includes conditioning the second input signal prior to modifying the second input signal.

59. The method of claim 58 wherein conditioning the second input signal includes at least partially saturating the second input signal with respect to a target frequency.

60. The method of claim 58 wherein conditioning the second input signal includes at least partially saturating with respect to a target frequency a signal provided by a signal generation circuit and combining the at least partially saturated signal with the second input signal.

62. The method of claim 55 wherein adjusting at least one of phase, delay, amplitude magnitude, amplitude sign, and frequency spectrum of the modified second input signal with respect to the first input signal includes using a feed-forward method.

63. The method of claim 55 wherein adjusting at least one of phase, delay, amplitude magnitude, amplitude sign, and frequency spectrum of the modified second input signal with respect to the first input signal includes performing a deterministic algorithm.

64. The method of claim 63 wherein performing a deterministic algorithm includes determining an amplitude (α

) of the first input signal, introducing a first phase shift (φ

1) into at least one of the first input signal and the modified second input signal, determining a first amplitude (β

) of the output signal, determining a target phase shift (φ

) based on a relationship between α and

β

, and introducing the target phase shift φ

into the at least one of the first input signal and the modified second input signal.

65. The method of claim 64 wherein determining Φ

based on a relationship between α and

β

comprises calculating a first pair of prospective phase shifts using the equation [[Φ

1=φ

1+/−

2A COS(β

/2α

)]] Φ

P1=φ

1+π

+/−

2AR COS(β

/2α

), and selecting one phase shift from the first pair of prospective phase shifts Φ

P1 as the target phase shift Φ

.

66. The method of claim 65 wherein performing the deterministic algorithm includes introducing a second phase shift (φ

2) into the at least one of the first input signal and the modified second input signal, determining a second amplitude (δ

) of the output signal, calculating a second pair of prospective phase shifts using the equation [[Φ

2=φ

2+/−

2A COS(δ

/2α

)]] Φ

P2=φ

2+π

+/−

2AR COS(δ

/2α

), and selecting one phase shift from the first and second pairs of prospective phase shifts Φ

P1 and Φ

P2 as the target phase shift Φ

.

67. The method of claim 55 wherein the first input signal for which wideband frequency and bandwidth tunable filtering is required is a received signal Rx that contains both a desired signal S and transmit interference Tx′

, wherein the second input signal comprises data to be transmitted Tx, and wherein the output signal having the desired frequency response comprises a filtered output signal that contains S and in which the presence of transmit interference Tx′

is reduced.

68. The method of claim 67 wherein received signal Rx is received from a first antenna, data to be transmitted Tx is sent from a second antenna, and transmit interference Tx′

comprises interference from the second antenna.

69. The method of claim 67 wherein received signal Rx is received from a first antenna, data to be transmitted Tx is sent from the first antenna, and transmit interference Tx′

comprises signal reflections within the first antenna.

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70. A non-transitory computer readable medium having stored thereon executable instructions that when executed by the processor of a computer control the computer to perform steps comprising:

receiving an input signal for which wideband frequency and bandwidth tunable filtering is desired;

creating a second input signal having at least one of a desired phase, amplitude, and delay relative to the first input signal;

modifying the second input signal to create a modified second input signal having a desired frequency spectrum, wherein creating the modified second input signal having the desired frequency spectrum includes creating a third input signal having at least one of a desired phase, amplitude, and delay relative to the second input signal, modifying the third input signal to produce a fourth input signal, and combining the second input signal and the fourth input signal to create the modified second input signal having the desired frequency spectrum;

adjusting at least one of phase, delay, amplitude magnitude, amplitude sign, and frequency spectrum of the modified second input signal with respect to the first input signal; and

combining the modified second input signal with the first input signal to create an output signal having the desired frequency response.