A narrow-band delta-sigma frequency-to-digital converter

This paper describes a novel frequency-to-digital conversion technique based on the D flip-flop frequency delta-sigma concept. It is shown that given some frequency constraints, there is no need for using a sampling frequency twice the maximum FM frequency. For narrow-band FM demodulation, it is further shown that by sampling the clock signal width of the FM signal, the digital resolution is more effectively increased by raising the constant clock frequency. A narrow-band D flip-flop frequency-to-digital converter have been realized in a FPGA confirming the theory.