Patent ID: 6473471
Filing Date: 2002-10-29
Classification: H03D,H04L

Abstract:
An improved radio receiving apparatus for direct conversion of signals to a baseband for processing, comprising:direct conversion means for converting a radio input signal to a complex baseband signal having a real waveform and an imaginary waveform; and slope and offset compensation means for estimating offsets and systematic drifts in said real and imaginary waveforms and compensating for said drifts and offsets such that decoding of information modulated on said radio input signal is substantially unimpaired, said slope and offset compensation means comprising: integrating capacitors which are driven to follow the input real and imaginary waveforms by a charge or discharge current pulse from charge pumps; comparator means for comparing the real and imaginary waveforms with a voltage on said integrating capacitors to generate a positive/negative indication; processing means for determining correction values for said real and imaginary waveforms wherein said correction values are used to select current magnitudes to be applied to said charge pumps, said current magnitudes being stored in one of register pairs and pairs of memory positions and said current magnitudes, for each pair of said one of register pairs and pairs of memory positions, are independent for positive and negative stepsign.