Sigma delta rf modulator having capacitive coupling, analog/digital converter and apparatus including such a modulator

Abstract

A continuous-time sigma delta radio frequency modulator is provided, including at least two LC resonators coupled in parallel by a coupling capacitive element, producing an at least 4-order bandpass filter, a frequency response of the bandpass filter presenting at least two poles that can be brought closer together or moved further apart depending on the capacitive element value; a feedback loop for shaping the quantization noise with a predetermined noise transfer function; and an adder for receiving: at one of its inputs an analog signal; and at its other input a signal provided by the feedback loop; and the output of which is linked to the input of the bandpass filter, the feedback loop including a finite impulse response filter, the coefficients of which being calculated to obtain a noise transfer function which maximizes the signal-to-noise ratio in a signal bandwidth while ensuring the stability of the feedback loop.