Patent ID: 7555279

Claim:
A direct conversion RF receiver comprising: an RF antenna adapted to receive an RF signal; a preselect filter adapted to filter the incoming RF signal; a low noise amplifier adapted to amplify the received RF signal; a local oscillator producing a local oscillation signal having a frequency tuned to that of the received RF signal; a first RF mixer along an in-phase channel path adapted to multiply a received radio frequency signal with the local oscillation signal; a second RF mixer along a quadrature-phase channel path adapted to multiply the received radio frequency signal with a 90° phase-shifted version of the local oscillation signal; a first low pass filter filtering an output of the first mixer thereby outputting a downconverted in-phase signal I, centered at baseband; a second low pass filter filtering an output of the second mixer thereby outputting a downconverted quadrature phase signal Q centered at baseband; and a residual DC correction circuit adapted to perform a time derivative and subsequent integration of the I and Q signals, wherein the time derivative and subsequent integration comprise solving the following algebraic expressions: Y i =X i −X i=1 , Z i =Y i +K·T s ·Z i−1 where K is a gain constant, T s is the sample time interval, X i is the signal stream, and Z i is the original signal less any constant terms.