Method and apparatus for cancellation of third order intermodulation distortion and other nonlinearities
First Claim
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1. An apparatus for substantially reducing nonlinear distortion, the apparatus comprising:
- a first coupler having an input and first and second outputs, the first coupler capable of splitting an input signal into first and second coupled signals having equal amplitude and in-phase with respect to each other;
a first nonlinear device having an input in communication with the first output of the first coupler and an output;
a second nonlinear device having an input in communication with the second output of the first coupler and an output; and
a second coupler having a first input in communication with the output of the first nonlinear device, a second input in communication with the output of the second nonlinear device and an output, the second coupler capable of 180 degree phase shifting an output signal of the second nonlinear device and coupling the phase shifted output signal of the second nonlinear device with an output signal of the first nonlinear device to generate a final output signal, wherein the first nonlinear device defines a gain as G1 dB, the second nonlinear device defines a gain as G2 dB, the first nonlinear device defines a third order output intercept point as OIP31 dBm and the second nonlinear device defines a third order output intercept point as OIP32 dBm such that the first and second nonlinear devices are provided such that most nearly 2(OIP31−
OIP32)=3(G1-G2), where G1 is not equal to G2.
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Abstract
Methods and apparatus are provided for substantially reducing and/or canceling nonlinearities of any order in circuits, devices, and systems such as amplifiers and mixers. In particular, methods and apparatus are provided for substantially reducing and/or canceling third order nonlinearities in circuits, devices, and systems such as amplifiers and mixers. A first coupler is used to split an input signal into two equal-amplitude in-phase components, each component is processed by two nonlinear devices with different nonlinearities, and a final combiner, such as a 180-degree hybrid, recombines the processed signals 180 degrees out of phase and substantially reduces and/or cancels the undesired nonlinear distortion components arising due to nonlinearities in the nonlinear devices.
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Citations
35 Claims
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1. An apparatus for substantially reducing nonlinear distortion, the apparatus comprising:
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a first coupler having an input and first and second outputs, the first coupler capable of splitting an input signal into first and second coupled signals having equal amplitude and in-phase with respect to each other;
a first nonlinear device having an input in communication with the first output of the first coupler and an output;
a second nonlinear device having an input in communication with the second output of the first coupler and an output; and
a second coupler having a first input in communication with the output of the first nonlinear device, a second input in communication with the output of the second nonlinear device and an output, the second coupler capable of 180 degree phase shifting an output signal of the second nonlinear device and coupling the phase shifted output signal of the second nonlinear device with an output signal of the first nonlinear device to generate a final output signal, wherein the first nonlinear device defines a gain as G1 dB, the second nonlinear device defines a gain as G2 dB, the first nonlinear device defines a third order output intercept point as OIP31 dBm and the second nonlinear device defines a third order output intercept point as OIP32 dBm such that the first and second nonlinear devices are provided such that most nearly 2(OIP31−
OIP32)=3(G1-G2), where G1 is not equal to G2.- View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for substantially reducing nonlinear distortion, the apparatus comprising:
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an input coupling means having an input and first and second outputs, the input coupling means splits an input signal into a first and second in-phase coupled signals;
a first nonlinear device having an input in communication with the first output of the input coupling means and an output;
a second nonlinear device having an input in communication with the second output of the input coupling means and an output; and
a second coupling means having a first input in communication with the output of the first nonlinear device, a second input in communication with the output of the second nonlinear device and an output, wherein the second coupling means 180-degree phase shifts and multiplies by a constant factor, k2, an output signal of the second nonlinear device and combines such with the output of the first nonlinear device, to generate a final output signal having substantially reduced nonlinear distortion, wherein the first nonlinear device defines a G1 dB, the second nonlinear device defines a gain as G2 dB, the first nonlinear device defines a third order output intercept point as OIP31 dBm and the second nonlinear device defines a third order output intercept point as OIP32 dBm, such that K1=10 log10(p2/p1), where p1 is the input signal power level of the first nonlinear device and p2 is the input signal power level of the second nonlinear device, K2=20 log10(k2), where k2 is the multiplicative factor established by the second coupling means, such that the input coupling means, the second coupling means, and the first and second nonlinear devices are provided such that most nearly 2(OIP31−
OIP32−
K2)=3(G1−
G2−
K1−
K2), and where G1 is not equal G2+K1+K2, to substantially reduce third order nonlinear distortion.- View Dependent Claims (7, 8, 9, 10, 11)
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12. An apparatus for substantially reducing nonlinear distortion, the apparatus comprising:
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a first coupler having an input and first and second outputs, the first coupler capable of splitting an input signal into first and second coupled signals having equal amplitude and in-phase with respect to each other;
a first nonlinear device having an input in communication with the first output of the first coupler and an output;
a second nonlinear device having an input in communication with the second output of the first coupler and an output; and
a second coupler having a first input in communication with the output of the first nonlinear device, a second input in communication with the output of the second nonlinear device and an output, the second coupler capable of 180 degree phase shifting an output signal of the second nonlinear device and coupling the phase shifted output signal of the second nonlinear device with an output signal of the first nonlinear device to generate a final output signal, wherein the first nonlinear device is provided such that it has a Taylor series expansion describing the output signal of the first nonlinear device, y1, in terms of an input signal of the first nonlinear device, x1, as y1=a0+a1x1+a2x12+a3x13+a4x14 . . . , the second nonlinear device is provided such that it has a Taylor series expansion describing the output signal of the second nonlinear device, y2, in terms of an input signal of the second nonlinear device, x2, as y2=b0+b1x2+b2x2+b3x23+b4x24 . . . , such that nonlinearities of order n are substantially reduced by setting most nearly an=bn, and a1 does not equal b1. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. An apparatus for substantially reducing nonlinear distortion, the apparatus comprising:
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an input coupling means having an input and first and second outputs, the input coupling means splits an input signal into a first and second in-phase coupled signals;
a first nonlinear device having an input in communication with the first output of the input coupling means and an output;
a second nonlinear device having an input in communication with the second output of the input coupling means and an output; and
a second coupling means having a first input in communication with the output of the first nonlinear device, a second input in communication with the output of the second nonlinear device and an output, wherein the second coupling means 180-degree phase shifts and multiplies by a constant factor, k2, an output signal of the second nonlinear device and combines such with the output of the first nonlinear device, to generate a final output signal having substantially reduced nonlinear distortion, wherein the first nonlinear device is provided such that it has a Taylor series expansion describing the output signal of the first nonlinear device, y1, in terms of an input signal of the first nonlinear device, x1, as y1=a0+a1x1+a2x12+a3x13+a4x14 . . . , the second nonlinear device is provided such that it has a Taylor series expansion describing the output signal of the second nonlinear device, y2, in terms of an input signal of the second nonlinear device, x2, as y2=b0+b1x2+b2x22+b3x23+b4x24 . . . , where the ratio k1=x2/x1, k2 is determined by selection of the second coupling means and where nonlinearities of order n are substantially reduced by setting most nearly an−
k2bnk1n=0, and such that a1−
k2b1k does not equal zero.- View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. An apparatus for substantially reducing nonlinear distortion, the apparatus comprising:
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an input coupling means having an input and first and second outputs, the input coupling means splits an input signal into a first and second in-phase coupled signals;
a first nonlinear device having an input in communication with the first output of the input coupling means and an output;
a second nonlinear device having an input in communication with the second output of the input coupling means and an output; and
a second coupling means having a first input in communication with the output of the first nonlinear device, a second input in communication with the output of the second nonlinear device and an output;
an adaptive control and feedback means having an input in communication with the output of the second coupling means and an output in communication with the first and second coupling means and the first and second nonlinear devices, wherein the second coupling means 180-degree phase shifts and multiplies by a constant factor, k2, an output signal of the second nonlinear device and combines such with the output of the first nonlinear device, to generate a final output signal having substantially reduced nonlinear distortion and the adaptive control and feedback means controls the nonlinearity, gain and phase of the first and second coupling means and the first and second nonlinear devices. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35)
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Specification
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Current AssigneeUniversity of North Carolina At Charlotte (University of North Carolina System)
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Original AssigneeUniversity of North Carolina At Charlotte (University of North Carolina System)
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InventorsWeldon, Thomas Paul
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Primary Examiner(s)Choe, Henry
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Application NumberUS10/101,005Publication NumberTime in Patent Office917 DaysField of Search330/149, 330/124.R, 330/254, 330/295, 330/84, 333/117US Class Current330/149CPC Class CodesH03F 1/3205 in field-effect transistor ...H03F 1/3211 in differential amplifiersH03F 1/3229 using a loop for error extr...H03F 1/3241 using predistortion circuit...
