In-line predistorter for linearization of electronic and optical signals

A predistortion circuit comprising:

• means for inputing an input modulation signal for a nonlinear device into an in-line electrical path;
• means in the in-line electrical path for generating primarily a real component of at least second order intermodulation products having a relative amplitude proportional to the amplitude of distortion in the nonlinear device;
• means in the in-line path for generating primarily imaginary components having at least second order intermodulation products proportional to the distortion of the nonlinear device;
• and
• a nonlinear device coupled to the output of the in-line electrical path for modulation by a predistorted output signal comprising the input modulation signal and intermodulation product predistortion generated in the in-line electrical path.

A predistortion circuit comprising:

• a nonlinear transmission device having an input for receiving modulation signals on an in-line path;
• at least one distortion producing element on the in-line path for primarily generating distortion products of fundamental input frequency signals in the modulation signals substantially proportional to a real component of distortion produced by the nonlinear device;
• at least one other distortion producing element on the in-line path for primarily generating distortion products of fundamental input frequency signals in the modulation signals substantially proportional to an imaginary component of predistortion produced by the nonlinear device;
• and
• at least one filter on the in-line path for filtering the modulation signals applied to the nonlinear device as a function of frequency.

A predistortion circuit comprising:

• an input and an output for a signal having fundamental frequencies;
• real means connected between the input and the output for generating primarily a real component of intermodulation products of the fundamental frequencies;
• imaginary means connected between the input and the output for generating primarily an imaginary component of intermodulation products of the fundamental frequencies;
• means for adjusting the real and/or imaginary means for producing a vector sum of the real and imaginary components having an amplitude equal and opposite to the distortion of a nonlinear device;
• and
• a nonlinear device in line with the real and imaginary means having inherent distortion with a vector sum substantially opposite to the vector sum of the real and imaginary components.

A predistortion circuit for generating frequency dependent predistortion having a sign opposite to distortion produced by a non-linear device and having substantially the same magnitude as the distortion produced by the nonlinear device, the circuit comprising:

• an input for receiving an RF signal for the nonlinear device;
• and
• means, in-line with a nonlinear element and the non-linear device, for producing distortion that varies as a function of frequencies of the input signal,
• wherein the predistortion circuit does not include a splitter for splitting the RF signal into first and second electrical paths, the first electrical path for transmitting fundamental signal, and the second path for generating predistortion.

A predistortion circuit for generating frequency dependent predistortion having a sign opposite to distortion produced by a nonlinear device and having substantially the same magnitude as the distortion produced by the nonlinear device, the circuit comprising:

• an input for receiving an RF signal for the nonlinear device;
• and
• means, comprising a non-linear element in-line with the non-linear device, for producing predistortion that varies as a function of frequencies of the input signal wherein the nonlinear element comprises a pair of antiparallel diodes,
• wherein the predistortion circuit does not include a splitter for splitting the RF signal into first and second electrical paths, the first electrical path for transmitting fundamental signal, and the second path for generating predistortion.

A predistortion circuit for generating frequency dependent predistortion having a sign opposite to distortion produced by a non-linear device and having substantially the same magnitude as the distortion produced by the nonlinear device, the circuit comprising:

• an input for receiving an RF signal for the nonlinear device:
• and means, including a nonlinear element, for producing distortion that varies as a function of frequencies of the input signal, the means further including:
• a first electric path containing one or more reactive elements;
• and
• a second electric path in-line with the first electric path, wherein the nonlinear element is in the second electric path and the reactive elements in the first electric path are used to regulate the amount of distortion produced by the nonlinear element as a function of frequencies of the RF signal.

A predistortion circuit for generating frequency dependent predistortion having a sign opposite to distortion produced by a nonlinear device and having substantially the same magnitude as the distortion Produced by the nonlinear device, the circuit comprising:

• an input for receiving an RF signal for the nonlinear device;
• and
• means, including a pair of antiparallel diodes, for producing predistortion that varies as a function of frequencies of the input signal, the means further including:
• a first electric path containing one or more reactive elements;
• and
• a second electric path in-line with the first electric path, wherein the antiparallel diodes are in the second electric path and the reactive elements in the first electric path are used to regulate the amount of distortion produced by the antiparallel diodes as a function of frequencies of the RF signal.