Apparatus with distortion cancelling feedback signal
AssigneeRockwell International Corporation
InventorMichael R. Vagher
Life of this patent
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Abstract
An apparatus having a distortion cancelling feedback signal that suppresses undesired signal components. One embodiment of the present invention is comprised of a balanced mixer coupled to a common-mode detector, a filter and having a resulting feedback signal that suppresses the common-mode component of the mixer output signal while allowing the differential component of the mixer output signal to pass on to additional processing.
Claims3
An apparatus having a closed-loop control signal for suppressing common-mode signal distortion comprising:
- a balanced mixer having an output signal with a differential and a common-mode component;
- a low-pass filter coupled to the output signal of the balanced mixer having characteristics that pass baseband frequency signals of the balanced mixer output signal;
- a level shift detector coupled to the passed signals of the low-pass filter, thereby yielding an extracted signal;
- a common-mode detector coupled to the level shift detector extracted signal that suppresses the common-mode component of the extracted signal;
- a voltage controlled current source having an input signal from the common-mode detector and having its output signal coupled to the balanced mixer;
- and
- an amplifier disposed between and coupled to the common-mode detector and the current source.
A method for suppressing distortion in a RF receiver comprising the following steps:
- mixing a received RF signal with an output signal of a local oscillator thereby creating an intermediate signal;
- filtering the local oscillator and RF frequencies from the intermediate signal;
- extracting the resultant signal of the filtering step;
- suppressing common-mode component of the RF signal at the resultant extracted signal;
- amplifying the resultant signal of the suppressing step;
- and
- electrically coupling the resultant signal of the suppressed extracted signal to a current source that provides a current signal to the mixing step.
Dependencies are inferred from the claim text.