초록 ▼

A method and apparatus for adaptively correcting D.C. offset errors imposed upon signals in a communication device. The present invention includes a feedback loop correction circuit and method for measuring and reducing D.C. offset errors imposed upon analog transmission signals by transmit digital-

A method and apparatus for adaptively correcting D.C. offset errors imposed upon signals in a communication device. The present invention includes a feedback loop correction circuit and method for measuring and reducing D.C. offset errors imposed upon analog transmission signals by transmit digital-to-analog converters (DACs) and associated analog reconstruction filters. A digital feedback loop is used to remove the D.C. offset errors from the analog transmission signals prior to transmission. In the preferred embodiment, the digital feedback loop includes a pair of analog-to-digital converters, a digital D.C. offset correction circuit, and a pair of adders. The transmission signals are digitized, filtered, and digitally processed by the correction circuit to generate offset correction signals that are equal to the undesired D.C. offset error present in the transmission signals. The correction signals are added to the digital input baseband signals thereby removing the undesirable D.C. offset errors from the transmission signals.

대표청구항 ▼

[ I claim:] [1.]1. A D.C. offset correction circuit for removing D.C. offset errors from baseband transmission signals in a communications device, the device receiving digital baseband input signals, wherein the input signals are converted to analog signals by transmit digital-to-analog converters,

[ I claim:] [1.]1. A D.C. offset correction circuit for removing D.C. offset errors from baseband transmission signals in a communications device, the device receiving digital baseband input signals, wherein the input signals are converted to analog signals by transmit digital-to-analog converters, and wherein the analog signals are filtered by reconstruction filters to produce the baseband transmission signals, comprising:a) an analog-to-digital (A/D) converter disposed to convert the transmission signals to digital feedback signals;b) a D.C. offset correction digital signal processing block having at least one input operatively coupled to the A/D converter, wherein the offset correction block is structured to process the digital feedback signals to produce D.C. offset correction signals nominally equal to the D.C. offset errors; andc) an adder, operatively coupled to the offset correction block, the adder having a first input connected to receive the input signals and a second input connected to receive the offset correction signals, wherein the adder is connected to add the correction signals to the input signals and to thereby remove the D.C. offset errors from the transmission signals.