Patent ID: 6943715

Claim:
A bandpass Sigma-Delta analog-to-digital converter including: a first analog adder having an output, a first input receiving samples of an analog input signal to be converted and a second input receiving samples of a first analog feedback signal; a first second-order resonator, the center frequency of which is adjustable, and having an output and an input receiving samples delivered by said output of said first analog adder; a second analog adder having an output, a first input receiving samples delivered by said output of said first resonator, a second input receiving samples of a second analog feedback signal, and third output receiving samples of said analog input signal to be converted; a second second-order resonator, the center frequency of which is adjustable, having an output and an input receiving the samples delivered by said output of the second analog adder; an analog-to-digital converter having an input receiving samples delivered by the output of the second resonator and an output delivering values of a digital output signal corresponding to the converted analog input signal; a first feedback loop that includes a digital-to-analog converter having an input receiving values of said digital output signal, and an output delivering said samples of said first analog feedback signal; a second feedback loop that includes said digital-to-analog converter and comprises an output delivering said samples of said second analog feedback signal, wherein the first resonator has a transfer function H 1 (z) given by the following relationship: H 1 ( z )=[(cos θ 1 × z −1 )− z −2 ]/[(1−(2×(cos θz −1 )+ z −2 ] and/or wherein the second resonator has a transfer function H 2 (z) given by the following relationship: H 2 ( z )=[(cos θ 2 × z −1 )− z −2 (1−(2×(cos θ 2 × z −1 )+ z −2 ] where z denotes the discrete-time frequency variable, and where θ 1 and θ 2 denote the argument of the variable z for the transfer function H 1 (z) and for the transfer function H 2 (z), respectively, and wherein the central frequency of the first resonator and/or the central frequency of the second resonator are adjustable via parameter cos θ 1 and/or parameter cos θ 2 , respectively.