The MZM was polarized with a DC power supply, whose voltage was varied in the range of 0-8 V. The electrical signal produced by the optical receiver was observed in a spectrum analyzer. The peak value of the second and third harmonics versus MZM polarization voltage, V pol , can be seen in Figure 3 for the 1 GHz signal and in Figure 4 for the 2 GHz signal.As can be noted in Figures 3 and 4, in both cases, the amplitude of the third harmonic is almost invariant with V pol . On the other hand, the production of the second harmonic is highly dependent of V pol . However, the best value of V pol depends on the frequency of the RF signal. It is about 7.5 V for the 1 GHz RF signal and 6 V for the 2 GHz RF signal.
CONCLUSIONSWe have presented two setups for photonic generation of harmonics. The theoretical setup, based on 2 Â 1 MZM and fiber loop, shows a complex dynamic and simplifications in the signal generator's parameters were necessaries to obtain a useful result: the production of four (2, 4, 6, and 8) even harmonics. On the other hand, the experimental setup using double amplitude modulation can produce the second and third harmonics. However, the efficiency depends on the frequency of the RF signal used and polarization voltage applied on the MZM.ABSTRACT: This article presents the full design methodology and implementation of inverse Class-F power amplifier with a commercial high-power GaN HEMT. For a 3.48 GHz continuous wave signal, the measurement results show state-of-the-art power-added-efficiency (PAE) of 76.7%, drain efficiency of 81.1%, gain of 12.9 dB, and output power of 39.9 dBm. Within a bandwidth of 200 MHz, drain efficiency and output power are maintained above 60% and 38.5 dBm, respectively. With digital predistortion, it achieves À45 dBc of adjacent channel leakage ratio for a 2.5 MHz wideband signal with a peak-to-average power ratio of 8.9 dB, with an average PAE of 36.7%. V C 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:521-525, 2012; View this article online at wileyonlinelibrary.com.
