Patent ID: 6320459
Filing Date: 2001-11-20
Classification: G11C,H03H

Abstract:
A filter system comprising:a first low pass filter comprising:an input on which is placed an input signal,an output on which is generated an output signal,a storage means for providing storage of a signal sample over time, a first end of the storage means coupled to the output,a switching means, coupled between the first end of the storage means and the input, for, when closed, electrically coupling the input to the first end of the storage means, and for when open electrically isolating the input from the first end of the storage means, anda control means, for controlling the switching means, the control means generating a switching control signal, the switching control signal having a sampling frequency, wherein a maximum cutoff frequency of the low pass filter is dependent on a value of a capacitance provided by the storage means and a pulse width of the switching control signal;a first summer circuit that subtracts the output signal on the output of the first low pass filter from the input signal to produce a high pass output signal;a second low pass filter that receives the high pass output signal and produces a bandpass filtered output; and,a second summer circuit that subtracts the bandpass filtered output from the input signal to produce a notch filtered output.