Determination of transmitter distortion
AssigneeBroadcom Corporation
InventorsJohn L. Creigh, Oscar E. Agazzi
Life of this patent
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Abstract
The present invention provides a method for determining nonlinear distortion of a transmitter. A test symbol sequence is transmitted from the transmitter under test as an analog output signal. The analog output signal is sampled to produce a first sequence which represents the test symbol sequence as distorted by a linear distortion sequence and a nonlinear distortion sequence. The test symbol sequence is filtered via an adaptive filter to produce a second sequence such that the second sequence is approximately equal to the test symbol sequence as distorted by the linear distortion sequence. The second sequence is subtracted from the first sequence to produce an output sequence substantially equal to the nonlinear distortion sequence.
Claims26
A method for determining nonlinear distortion of a transmitter, the method comprising the operations of:
- (a) transmitting a test symbol sequence from the transmitter as an analog output signal;
- (b) sampling the analog output signal to produce a first sequence, the first sequence representing a combination of the test symbol sequence, a linear distortion sequence and a nonlinear distortion sequence;
- (c) filtering the test symbol sequence via an adaptive filter to produce a second sequence such that the second sequence is approximately equal to a combination of the test symbol sequence and the linear distortion sequence;
- and
- (d) combining the first sequence and the second sequence via an adder to produce an output sequence substantially equal to the nonlinear distortion sequence.
A method for determining nonlinear distortion of a transmitter, the method comprising the operations of:
- (a) transmitting a test symbol sequence from the transmitter as an analog output signal;
- (b) sampling the analog output signal to produce a set of sampled data;
- (c) fitting a sinusoidal sequence to the sampled data;
- (d) subtracting the sinusoidal sequence from the sampled data to produce a first sequence, the first sequence representing a combination of the test symbol sequence, a linear distortion sequence and a nonlinear distortion sequence;
- (e) filtering the test symbol sequence via an adaptive filter having coefficients to produce a second sequence such that the second sequence is approximately equal to a combination of the test symbol sequence and the linear distortion sequence, the filter coefficients being adapted based on a difference between the first and second sequences;
- and
- (f) combining the first sequence and the second sequence via an adder to produce an output sequence substantially equal to the nonlinear distortion sequence.
A system for determining nonlinear distortion of a transmitter, the system comprising:
- (a) the transmitter transmitting a test symbol sequence as an analog output signal;
- (b) a sampler sampling the analog output signal to produce a first sequence, the first sequence representing a combination of the test symbol sequence, a linear distortion sequence and a nonlinear distortion sequence;
- (c) an adaptive filter filtering the test symbol sequence to produce a second sequence such that the second sequence is approximately equal to a combination of the test symbol sequence and the linear distortion sequence;
- and
- (d) an adder combining the first sequence and the second sequence to produce an output sequence substantially equal to the nonlinear distortion sequence.
A system for determining nonlinear distortion of a transmitter, the system comprising:
- (a) a transmitter transmitting a test symbol sequence as an analog output signal;
- (b) a sampler sampling the analog output signal to produce a set of sampled data;
- (c) a best fit module fitting a sinusoidal sequence to the sampled data;
- (d) a first adder subtracting the sinusoidal sequence from the sampled data to produce a first sequence, the first sequence representing a combination of the test symbol sequence, a linear distortion sequence and a nonlinear distortion sequence;
- (e) an adaptive filter having coefficients, the adaptive filter filtering the test symbol sequence to produce a second sequence such that the second sequence is approximately equal to a combination of the test symbol sequence and the linear distortion sequence, the filter coefficients being adapted based on a difference between the first and second sequences;
- and
- (f) a second adder combining the first sequence and the second sequence to produce an output sequence substantially equal to the nonlinear distortion sequence.
Dependencies are inferred from the claim text.