the product of the input signal tc_adc n and scaling signal tc_ki further summed with a prior stored output signal of the integral process as defined in equation 2 below derivative process module 48 comprises multiplier element 49 delay element 50 and summing element 52 in the signal path configuration as illustrated in fig2 derivative process module 48 performs a derivation function and generates an output signal adc_kd_out n representing the difference between the current and previous input signal vales tc_adc n and tc_adc n u2212 1 further scaled by signal tc_kd as defined in equation 3 below adc _ kd _out n tc _ kd tc _ adc n tc _ adc n u2212 1 equation 3 the output values of process module 36 integral process module 42 and derivative process module 48 are combined by summing elements 38 as defined in equation 4 below pid _out1 n adc _ kp _out n adc _ ki _out n adc _ kd _out n equation 4 the pid_out 1 n signal may then be clipped as necessary by a clipping element 39 prior to being summed with the tc_init signal the tc_init signal is the initial set point for the entire quadrature error cancellation feedback loop.