In-line distortion cancellation circuits for linearization of electronic and optical signals with phase and frequency adjustment
View Patent ↗A distortion circuit is provided for correcting the distortion from a nonlinear circuit element by generating a frequency dependent signal having a sign opposite to the distortion signal produced by the nonlinear circuit and substantially the same magnitude. The distortion circuit includes an input signal and a first nonlinear device coupled to the input signal for generating a first signal and where the first nonlinear device has a first bias level. Also included is a second nonlinear device different from same first nonlinear device and coupled to the first nonlinear device for modifying the first signal to produce an output second signal, the second nonlinear device having a second bias level. A bias control means is provided for adjusting the first and said second bias levels so that the magnitude, phase and frequency of the output second signal can be adjusted.
1. A distortion circuit for correcting distortion from a nonlinear circuit element by generating a frequency dependent signal having a sign opposite to the distortion signal produced by the nonlinear circuit and substantially the same magnitude comprising:
an input signal;
a resistor having a first terminal and a second terminal, the first terminal coupled to the input signal;
a first nonlinear device coupled to said second terminal of the resistor for generating a first signal that mainly creates a real portion of the distortion, the first nonlinear device being biased at a first biased level;
a capacitor having a first terminal and a second terminal, the first terminal coupled to the second terminal of the resistor;
a second nonlinear device different from same first nonlinear device and coupled to said second terminal of the capacitor for modifying said first signal to produce an output second signal, said second nonlinear device having a second bias level that mainly creates an imaginary portion of the distortion;
means for adjusting said first bias level so that the magnitude of the output second signal can be adjusted; and
means for adjusting said second bias level so that the phase and frequency of the output second signal can be adjusted.
2. The circuit of claim 1 wherein said first nonlinear element is a Schottky diode, and said second nonlinear element is a varactor diode.
3. The circuit of claim 1 wherein said first and said second nonlinear element are reversed-biased.
4. The circuit of claim 1 wherein said first nonlinear element is forward-biased.
5. The circuit of claim 1 , wherein one of said nonlinear elements is forward biased and the other nonlinear element is reversed biased.
6. The circuit of claim 1 , wherein said means for adjusting said second bias level includes a reactive component.
7. The circuit of claim 1 , wherein said means for adjusting said second bias level includes a varactor diode.
8. The circuit of claim 1 , wherein said second nonlinear device is a PIN diode acting as a linear variable resistor.
9. The circuit of claim 1 , wherein said means for adjusting said first and second bias levels permit simultaneous adjustment of second and third order distortion.
10. A distortion circuit for correcting distortion from a nonlinear circuit element by generating a frequency dependent signal having a sign opposite to the distortion signal produced by the nonlinear circuit and substantially the same magnitude comprising:
an input signal;
a first capacitor having a first terminal and a second terminal, the first terminal coupled to the input signal;
a first resistor having a first terminal and a second terminal, the first terminal coupled to the second terminal of the first capacitor;
a second capacitor having a first terminal and a second terminal, the first terminal coupled to the second terminal of the first capacitor;
a first diode coupled to said second terminal of the resistor for generating a first signal;
a first biasing voltage coupled to the second terminal of the resistor for biasing the first diode;
a third capacitor having a first terminal and a second terminal, the first terminal coupled to the second terminal of the resistor;
a second diode coupled to the second terminal of the third capacitor; and
a second biasing voltage coupled to the second terminal of the third capacitor for biasing the second diode.
11. The circuit of claim 10 , further comprising a first voltage divider for producing the first biasing voltage.
12. The circuit of claim 10 , further comprising a second voltage divider for producing the second biasing voltage.