Configurable system for cancellation of the mean value of a modulated signal

摘要

Some embodiments of the invention relate to a DC offset correction circuit comprising a feedback loop having a DAC controlled by a reconfigurable ADC, which determines (e.g., tracks) the mean value of a modulated input signal. The circuit operates according to two phase process. In a first “pre-modulation” tracking phase, an input signal is tracked by the ADC, which is configured to output the input signal's mean value as a digital code equivalent to the input mean value. The output of the ADC is provided to a DAC, which provides an analog representation of the mean value to an adder that subtracts the mean value from the modulated input signal to generate a bipolar adjusted input signal. In a second “modulation” phase, the estimated mean value is held constant, so that the bipolar adjusted input signal may be provided to an activated modulation circuit for improved system performance.

主权项

1. A circuit, comprising:
an input node configured to receive an input signal having a modulated component and a DC offset component; a modulation circuit configured to perform signal modulation and demodulation; a feedback loop comprising one or more circuit components configured to track a mean value of the input signal and to generate a DC offset correction signal from the mean value; and an adder coupled to the input node, an output of the feedback loop, and the input of the modulation circuit, wherein the adder is configured to subtract the DC offset correction signal from the input signal to generate a bipolar adjusted input signal, wherein the modulation circuit is selectively deactivated during a first operating phase so that the input signal is provided to the feedback loop and selectively activated during a second operating phase so that the bipolar adjusted input signal output from the adder is delivered to the modulation circuit before being provided to the feedback loop.