D.C. offset compensation in a radio receiver

In a radio receiver, an apparatus for compensating for DC offset in a signal comprising:

• means for generating a channel signal from a received radio signal;
• means for differentiating the channel to eliminate a DC component in the channel signal;
• means for amplifying a signal output from said differentiating means and producing an amplified signal;
• means for integrating the amplified signal to thereby recover said DC component;
• estimating means, connected to an output of said integrating means, for generating an estimate of an error in the recovered DC component;
• memory means, connected to said integrating means, for storing a restored signal output from said integrating means, wherein the restored signal includes the amplified signal and the recovered DC component;
• and
• means for subtracting the estimate of the error in the recovered DC component from the restored signal to produce a compensated restored signal.

A radio receiving apparatus for receiving an RF signal and applying said RF signal to first and second quadrature channels, comprising:

• a local oscillator;
• first and second mixers, associated with said first and second quadrature channels, respectively, each having one input for receiving said RF signal and a second input for receiving from said local oscillator sinusoidal signals at a carrier frequency of said RF signal;
• first and second differentiating means for respectively differentiating outputs from said first and second mixers in order to eliminate DC offset components generated by imbalances between said first and second mixers;
• first and second amplifying means for respectively amplifying outputs from said first and second differentiating means;
• and
• first and second integrating means for respectively integrating outputs from said first and second amplifying means to restore DC offset components of said outputs from said first and second mixers.

In a radio receiver, an apparatus for compensating for DC offset in a received signal, comprising:

• comparator means for comparing a received signal with a feedback signal and for generating a first digital value if said received signal exceeds said feedback signal and a second digital value if said received signal is less than said feedback signal;
• memory means for storing a sequence of digital values output from said comparator means;
• deciding means, connected to said memory means, for receiving said sequence of digital values and for deciding a current step value;
• first integrating means for integrating current step values received from said deciding means and for generating said feedback signal;
• and
• second integrating means for integrating said digital values received from said memory means in order to restore DC components of said received signal.

A radio receiving apparatus for receiving an RF signal and applying said RF signal to first and second quadrature channels, comprising:

• means for receiving said RF signal and separating said RF signal into first and second quadrature signals;
• first and second comparator means for comparing said first and second quadrature signals with first and second feedback signals respectively, and for generating a first digital value if said received signal exceeds said feedback signal and a second digital value if said received signal is less than said feedback signal;
• first and second memory means for storing corresponding sequences of said digital values generated by said first and second comparator means, respectively;
• first and second deciding means, connected to said first and second memory means, for receiving said sequences of digital values and for deciding a joint current step value;
• first and second integrating means for integrating joint current step values received from said deciding means and for generating said first and second feedback signals which are sent to said first and second comparator means, respectively;
• and
• first and second reintegrating means for reintegrating said corresponding digital values received from said first and second memory means in order to restore DC components of said received signal.

A radio receiver for receiving an RF signal and applying said RF signal to plural channels, comprising:

• means for receiving said RF signal and separating said RF signals into a plurality of channels signals;
• plural delta modulating means for receiving respective channel signals, each delta modulating means generating a digital output;
• plural memory means for storing digital sequences of digital outputs from corresponding ones of said plural delta modulating means;
• adaptive means, connected to said plural memory means, for adapting step value signals transmitted back to corresponding ones of said plural delta modulating means;
• and
• plural reintegrating means for integrating a corresponding digital output received from corresponding ones of said plural memory means in order to restore DC components of said channel signals.

A method for compensating for DC offset in a signal received in a multi-channel RF receiver, comprising:

• comparing a received signal with a feedback signal and generating a first digital value if said received signal exceeds said feedback signal and a second digital value if said received signal is less than said feedback signal;
• storing a sequence of said digital values produced in said comparing step;
• determining a current step value based on said sequence of digital values;
• integrating said current step value and generating said feedback signal;
• and
• reintegrating said digital values stored at said storing step in order to restore DC components of said received signal.