US 7,120,206 B2 · Signal DC offset correction method and device

Abstract

A method and a device for estimating the DC offset portion of a signal, especially of a signal containing parts with sinusoidal shape, for example a signal which results from demodulation of a frequency modulated receive signal. A method is presented for correcting the direct current offset portion (DC offset) of a first signal which includes phase shifting the first signal for obtaining a second signal and comparing the first signal and the second signal with an estimated DC offset. The estimated DC offset is adjusted if the result of the comparison is that the first signal and the second signal are on different sides of the estimated DC offset and the estimated DC offset remains constant as long as the result of the comparison is that the first signal and the second signal are on the same side of the estimated DC offset.

Claims15

Dependent claims

A method for correcting the direct current offset portion (DC offset) of a first signal comprising the steps of:

phase shifting said first signal for obtaining a second signal,
comparing said first signal and said second signal with an estimated DC offset,
adjusting the estimated DC offset when the first signal and the second signal are found to be on different amplitude sides of said estimated DC offset, wherein the estimated DC offset is increased when the second signal is higher than the estimated DC offset and is decreased when the second signal is lower than the estimated DC offset.

A device for correcting the direct current offset portion (DC offset) of a first signal comprising:

an input for connecting to a signal line for receiving said first signal,
a phase shifting element connected to the input for producing a phase shifted second signal,
means for providing an estimated DC offset, wherein said estimated DC offset is adjusted when said phase shifted second signal is connected to an input of said means and said estimated DC offset is held constant when said phase shifted second signal is disconnected from the input of said means,
an output signal line connected to the output of said means for providing said estimated DC offset,
a decision circuit for deciding whether said first signal and said phase shifted second signal are on different or same amplitude sides of said estimated DC offset, and
a switch for connecting said phase shifted second signal to the input of said means when said decision circuit decides that said first signal and said phase shifted second signal are on different amplitude sides of said estimated DC offset and disconnecting said phase shifted second signal from the input of said means when the decision circuit decides that said first signal and said phase shifted second signal are on the same side of said estimated DC offset.

3 more elements

Dependencies are inferred from the claim text.

Signal DC offset correction method and device

Life of this patent

Signal DC offset correction method and device

Life of this patent

Abstract

Claims15