Patent ID: 8660198

Claim:
A circuit for generating K in-phase and quadrature complex Fourier coefficients based on an OFDM signal modulated by a carrier frequency and having K sub-carriers, comprising: a sampling clock generator configured to generate an in-phase sampling clock and a quadrature sampling clock, the quadrature sampling clock being ninety degrees out of phase with the in-phase sampling clock, and the in-phase sampling clock and the quadrature sampling clock having the same frequency; a quadrature bandpass-sampling delta-sigma analog-to-digital demodulator (QBS-ADD) configured to demodulate the OFDM signal from the carrier frequency down to baseband, generate an in-phase signal based on the in-phase sampling clock and the demodulated OFDM signal, and generate a quadrature signal based on the quadrature sampling clock and the demodulated OFDM signal; first through P th bit processors, each of the first through P th bit processors being configured to delay the in-phase signal by an i th delay time equal to d i ×D, to generate an i th delayed in-phase signal, with D being a set delay time, delay the quadrature signal by the i th delay time equal to d i ×D, to generate an i th delayed quadrature signal, and capture the i th delayed in-phase signal and the i th delayed quadrature signal to generate K in-phase Fourier coefficients and K quadrature complex Fourier coefficients, j th in-phase and quadrature complex Fourier coefficients corresponding to a j th OFDM sub-carrier; a maximal ratio combiner configured to linearly combine, for each of the first through K th OFDM sub-carriers, the in-phase complex Fourier coefficients from each of the first through P th bit processors to generate a combined in-phase complex Fourier coefficient, thereby generating K combined in-phase complex Fourier coefficients corresponding to the K OFDM sub-carriers, and linearly combine, for each of the first through K th OFDM sub-carrier, the quadrature complex Fourier coefficients from each of the first through P th bit processors to generate a combined quadrature complex Fourier coefficient, thereby generating K combined quadrature complex Fourier coefficients corresponding to the K OFDM sub-carriers; wherein i is a first index value that varies from 1 to P, and represents a numeric identifier of one of the first through P th bit processors, wherein D is equal to the period of the in-phase sampling clock, wherein j is a second index value that varies from 1 to K, and represents a numeric identifier of one of first through K th OFDM subcarriers, and wherein P and K are integers greater than 1.