Patent ID: 7903772
Filing Date: 2011-03-08
Classification: H03D

Abstract:
1. A demodulator for use in a receiver to convert a digital baseband signal into inbound digital symbols, the demodulator comprising: a lowpass filter for filtering the digital baseband signal to produce a filtered digital baseband signal; an equalizer operating at a first sampling rate to equalize a frequency response of the digital baseband signal such that the receiver overall in-band frequency response approximates the frequency response of a desired filter to produce an adjusted digital baseband signal; an interpolator for receiving the adjusted digital baseband signal at the first sampling rate and interpolating the adjusted digital baseband signal to produce an interpolated digital baseband signal at a second sampling rate; a vector de-rotator for vector de-rotating the interpolated digital baseband signal at the second sampling rate to produce magnitude and phase information; and a demodulation module for producing the inbound digital symbols from the magnitude and phase information; wherein the interpolator includes a tapped delay line coupled to receive sequential sampled values of the adjusted digital baseband signal and a clock signal at the first sampling rate, wherein the tapped delay line outputs selected ones of the sequential sampled values at each clock of the clock signal; wherein the tapped delay line includes M delay elements sequentially coupled, each having a respective tap on an output thereof, wherein the tapped delay line further includes a single M×N multiplexer coupled to the tap of each of the M delay elements and coupled to receive a control signal, the multiplexer producing the output of N of the M delay elements based upon a value of the control signal as the selected sequential sampled values.