Patent ID: 8577945

Claim:
A method of canceling a fundamental frequency from an analog signal, said method comprising: inputting a first analog signal; outputting a second digital signal; employing a digital-to-analog converter comprising an input and an output; employing an analog-to-digital converter comprising an input and an output; inputting a third digital signal to and outputting a fourth analog signal representative of an estimate of a fundamental frequency component of the first analog signal from said digital-to-analog converter; inputting a fifth analog signal to said analog-to-digital converter and outputting from said analog-to-digital converter the second digital signal representative of the first analog signal with the fundamental frequency component removed; providing a first adaptive w s (n), and a second adaptive filter weight, w c (n); providing a first digital sine signal, x s (n)=sin(ω o n), and a second digital cosine signal, x c (n)=cos(ω o n); providing the third digital signal being y(n)=w s (n)*sin(ω o n)+w c (n)*cos(ω o n); employing ω o as frequency of the fundamental frequency component; employing n as an integer representative of a sample number; providing the fifth analog signal as a function of a difference between the first analog signal and the fourth analog signal; providing an optimum value of the first adaptive filter weight as being w s *=(A/G DAC (ω o ))cos(θ A −θ DAC (ω o )); providing an optimum value of the second adaptive filter weight as being w c =(A/DAC(ω o ))sin(θ A −θ DAC (ω o )); employing A=G DAC (ω o )√{square root over ([(w c *) 2 +(w s *) 2 ])}{square root over ([(w c *) 2 +(w s *) 2 ])}; employing θ A =tan −1 (w c */w s *)+θ DAC (ω o ); employing G DAC (ω o ) as magnitude of a transfer function of the digital-to-analog converter at the frequency of the fundamental frequency component; and employing θ DAC (ω o ) as phase of the transfer function of the digital-to-analog converter at the frequency of the fundamental frequency component.