Adaptive cancellation of time variant DC offset

A DC drift canceller circuit configured to receive an input signal, comprising:

• a decision device including an input and an output;
• a first adder configured to receive the input and output of the decision device and further configured to produce an error signal indicative of the difference between the input and output of the decision device;
• and
• a low pass filter operable to remove noise from the error signal, wherein the low pass filter includes a first multiplier configured to receive the error signal, a second adder connected with an input connected to the output of the first multiplier, a second multiplier with an input connected to the output of the second adder;
• and a time delay circuit with an input connected to the output of the second multiplier and an output connected to the second adder such that the output of the second adder is indicative of the difference between the output of the first multiplier and the output of the time delay circuit;
• and
• wherein the output of the noise filter is subtracted from the input signal to eliminate DC drift from the input signal.

A DC drift canceller circuit configured to receive an input signal, comprising:

• a decision device including an input and an output;
• a first adder configured to receive the input and output of the decision device and further configured to produce an error signal indicative of the difference between the input and output of the decision device;
• and
• a noise filter including an integrator and configured to receive the error signal and operable to remove noise from the error signal;
• wherein the output of the noise filter is subtracted from the input signal to eliminate DC drift from the input signal.

A method of canceling DC drift in a received signal comprising:

• generating a quantized signal responsive to the received signal;
• generating an error signal indicative of the difference between the received signal and the quantized signal;
• filtering noise from the error signal to produce a filtered error signal;
• using the filtered error signal to modify the received signal;
• and
• converting the received signal from an analog signal to a digital signal prior to generating the quantized signal.