A Novel Structure Optimizer Based on Heuristic Search for Delta-Sigma Modulator in Mobile Fronthaul

In this letter, a novel delta-sigma modulator structure design method based on the genetic algorithm is proposed. Compared to the widely adopted R.Schreier’s method, the proposed approach can significantly reduce the in-band quantization noise. Performance comparisons are carried out on 4th-order baseband delta-sigma modulators (DSMs) and 6th-order bandpass DSMs with center frequency at 2GHz. OSR of these delta-sigma modulators are set at 8. Numerical simulations, as well as experimental demonstrations, are conducted to show a 10-Gbaud intensity modulation direct detection transmission with the 64-QAM signal. Experimental results show that compared to R. Schreier’s method, the proposed GA method can improve the SNR by
$\sim 5$
dB and
$\sim 3$
dB for baseband DSM and bandpass DSM, respectively.