Patent ID: 9543978
Date: 2017-01-10
CPC Classifications: H03M

Claim:
1. A frequency selective circuit configured to convert an analog input signal to a digital output signal, comprising: an analog-to-digital converter configured to generate the digital output signal of the frequency selective circuit based on an analog input signal to the analog-to-digital converter; a digital-to-analog converter arranged to generate an analog feedback signal based on the digital output signal generated by the analog-to-digital converter; an analog filter arranged to generate the analog input signal to the analog-to-digital converter based on the analog feedback signal generated by the digital-to-analog converter and an analog input signal to the frequency selective circuit, wherein the analog filter comprises at least two integrators in series, each integrator having a feedback path comprising the analog-to-digital converter in cascade with a digital-to-analog converter, so that the overall noise transfer function of the frequency selective circuit has at least two zeros in addition to zeros in the noise transfer function of the analog-to-digital converter; and a resistor arranged to form a resonator loop around two integrators of the analog filter.