A 20GHz-Band Optical-Fiber-Feed 1-Bit Bandpass Delta-Sigma Direct Digital RF Transmitter Using First Image Component of the QSFP28 Module Output

In this paper, we firstly demonstrate a 20-GHz 1-bit band-pass delta-sigma (BP-DS) direct digital RF transmitter using 25GbE optical fiber link. By utilizing the first image component of the QSFP28 module output, RF signal at 20 GHz band is extracted from 1-bit BP-DS data stream whose the fundamental RF signal component is at 6.45 GHz band. From 5Mbps-QPSK signal (f
c
=19.33 GHz) transmission measurement, as a result, the output power of -28.6 dBm, SNR of 45.9 dB, EVM of 2.6% and ALCR≤-39.7 dBc are obtained in the 2
^nd
Nyquist zone.