Method and system for DC offset cancellation from a modulated signal
View Patent ↗Provided are a method and system for removing an offset direct current (DC) component from an input waveform. The method includes multiplying the input waveform with a demodulation waveform to produce a first differential current signal. An absolute value representation of the demodulation waveform is multiplied with a reference DC offset value to produce a second differential current signal. The first and second differential current signals are then differenced.
1. A method for removing an offset direct current (DC) component from a base-band signal, comprising:
multiplying the base-band signal with a demodulation waveform to produce a first differential current signal;
multiplying an absolute value representation of the demodulation waveform with a reference DC offset value to produce a second differential current signal; and
differencing the first and second differential current signals.
2. The method of claim 1 , wherein when (i) the base-band signal resembles a square wave shape and (ii) the demodulation waveform resembles a sine wave shape, (iii) the differential current signal resembles a rectified sine wave.
3. The method of claim 1 , wherein the reference DC offset value is user programmable.
4. The method of claim 1 , wherein the reference DC offset value is representative of an estimated an average of the offset DC component.
5. The method of claim 1 , wherein a shape of the second differential current signal is substantially similar to a shape of the first differential current signal.
6. The method of claim 1 , wherein the differencing extracts the offset DC component from the base-band signal.
7. An apparatus for removing an offset direct current (DC) component from an input waveform, comprising:
means for multiplying the input waveform with a demodulation waveform to produce a first differential current signal;
means for multiplying an absolute value representation of the demodulation waveform with a reference DC offset value to produce a second differential current signal; and
means for differencing the first and second differential current signals.
8. An apparatus for removing an offset direct current (DC) component from an input waveform, comprising:
a first demodulator having a first digital to analog converter (DAC) coupled thereto;
a second demodulator, coupled at least indirectly to the first demodulator, and having a second DAC coupled thereto; and
a third DAC coupled to one of the first and second demodulators and configured to provide a reference signal thereto;
wherein the other of the first and second demodulators is configured for programming of a demodulation waveform configured to match an input DC stimulation signal.