Methods and apparatus for substantially reducing nonlinear distortion using multiple nonlinear devices
First Claim
1. An apparatus for substantially reducing nonlinear distortion, the apparatus comprising:
- a first nonlinear device having an input and an output;
a second nonlinear device having an input and an output, the inputs of the first and second nonlinear devices are in communication with an input signal;
an attenuator having an input in communication with output of the first nonlinear device and an output;
a first subtractor having a first input in communication with the output of the second nonlinear device, a second input in communication with the output of the attenuator and an output;
wherein the first subtractor subtracts an output of the second nonlinear device from an output of the attenuator;
a third nonlinear device having an input in communication with the output of the first nonlinear device and an output;
a fourth nonlinear device having an input in communication with output of the first subtractor and an output; and
a second subtractor having a first input in communication with the output of the third nonlinear device, a second input in communication with the output of the fourth nonlinear device and an output, wherein the second subtractor subtracts the output of the fourth nonlinear device from the output of the third nonlinear device to form a final output signal.
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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
24 Claims
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1. An apparatus for substantially reducing nonlinear distortion, the apparatus comprising:
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a first nonlinear device having an input and an output;
a second nonlinear device having an input and an output, the inputs of the first and second nonlinear devices are in communication with an input signal;
an attenuator having an input in communication with output of the first nonlinear device and an output;
a first subtractor having a first input in communication with the output of the second nonlinear device, a second input in communication with the output of the attenuator and an output;
wherein the first subtractor subtracts an output of the second nonlinear device from an output of the attenuator;
a third nonlinear device having an input in communication with the output of the first nonlinear device and an output;
a fourth nonlinear device having an input in communication with output of the first subtractor and an output; and
a second subtractor having a first input in communication with the output of the third nonlinear device, a second input in communication with the output of the fourth nonlinear device and an output, wherein the second subtractor subtracts the output of the fourth nonlinear device from the output of the third nonlinear device to form a final output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. 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 that is capable of splitting an input signal into first and second in-phase 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;
an attenuator having an input in communication with output of the first nonlinear device and an output;
a second coupling means having a first input in communication with the output of the second nonlinear device, a second input in communication with the output of the attenuator and an output;
the second coupling means combines a 180 degree phase shifted and attenuated output of the second nonlinear device with an output of the attenuator;
a third nonlinear device having an input in communication with output of the first nonlinear device and an output;
a fourth nonlinear device having an input in communication with the output of the second coupling means and an output; and
a third coupling means having a first input in communication with the output of the third nonlinear device, a second input in communication with the output of the fourth nonlinear device and an output, wherein the third coupling means combines a 180 degree phase shifted and attenuated output of the fourth nonlinear device with the output of the third nonlinear device to form a final output signal. - View Dependent Claims (14, 15, 16, 17)
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18. A method substantially reducing nonlinear distortion, in accordance with an embodiment of the present invention comprising the steps of:
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transmitting an input signal to an input coupling means that splits the input signal into first and second in-phase coupled signals;
transmitting the first coupled signal to a first nonlinear device, having a Taylor series expansion describing a first nonlinear device output signal, y1, in terms of a first nonlinear device input signal x1, as y1=α
0+α
1x1+α
2x12+α
3x13+α
4x14 . . . ;
transmitting the second coupled signal to a second nonlinear device, having a Taylor series expansion describing a second nonlinear device output signal, y2 in terms of a second nonlinear device input signal, x2, as y2=b0+b1x2+b2x22+b3x23+b4x24 . . . , and with substantially equal time delay and phase in the first and second nonlinear devices;
transmitting the first nonlinear device output signal to an attenuator such that an attenuator output signal is, k times an attenuator input signal;
subtracting the second nonlinear device output signal from the attenuator output signal to form a difference signal;
transmitting the first nonlinear device output to a third nonlinear device, with Taylor series expansion describing a third nonlinear device output y3, in terms of a third nonlinear device input signal x3, as y3=c0+c1x3+c2x32+c3x33+c4x34 . . . ;
transmitting the difference signal to a fourth nonlinear device, with Taylor series expansion describing a fourth nonlinear device output signal, y4, in terms of a fourth nonlinear device input signal, x4, as y4=d0+d1x4+d2x42+d3x43+d4x44 . . . , and with substantially equal time delay and phase in the third and fourth nonlinear devices; and
subtracting the fourth nonlinear device output signal from the third nonlinear device output signal to form a final output signal. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification