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This paper presents the design of a wideband harmonically-tuned Doherty amplifier. The frequency-dependent back-off efficiency degradation was minimized by compensating the effect of the frequency-sensitive impedance inverters over the design band. Suitable choice of device size ratio as well as harmonic load tuning at back-off and maximum power operations were also considered, resulting in superior performance over the targeted design band. The maximum output power ranged from 48.2 dBm to 49.6 dBm. 6 dB back-off efficiencies of η 6dB ≥53 % (power-added efficiency PAE≥50 %) were measured over 1.7-2.25 GHz (28 % bandwidth). When linearized using digital pre-distortion (DPD), the Doherty amplifier had adjacent-channel leakage ratio (ACLR) of -43 dBc for a long-term evolution (LTE) signal at 1.85 GHz (η=50 %) and -44 dBc for a wideband code-division multiple access (W-CDMA) signal at 2.11 GHz (η=41 %), at average output power of 41.0 dBm and 40.5 dBm, respectively.Index Terms -Broadband amplifiers, Doherty amplifier, harmonic tuning, HEMTs, high power amplifiers.

This paper presents two new designs of MIMO dual band coplanar waveguide (CPW)-fed-slot antennas operating in the 5G frequency band (28 and 38 GHz). The first antenna is an XX MIMO antenna and the second antenna is an XY MIMO antenna. Simulated results for the S-parameters are presented for the two antennas using HFSS. Measured results are also presented for the return loss and gain with both results showing good agreement. The current distribution, group delay, envelope correlation coefficients (ECC), and diversity gain, are also presented for both antennas. The two antennas are fabricated on a substrate having dielectric constant ε r = 10.7 and substrate thickness 0.635 mm. The size of the antenna is 4.4 mm x 4.1 mm x 0.635 mm.

Design and analysis of 80-W wideband asymmetrical Doherty amplifier khaled bathich and georg boeckThis paper presents the analysis and design of a wideband asymmetrical Doherty amplifier. The frequency response of the output combining network of the Doherty amplifier with arbitrary back-off level configuration is analyzed. Other bandwidthlimiting factors were discussed and analyzed as well. A number of performance enhancement techniques were taken into consideration to obtain high and flat back-off efficiency over the amplifier design band of 1.7-2.25 GHz. The designed Doherty amplifier had, at 8.0-9.9 dB output back-off, a minimum efficiency of h ¼ 50% [power-added efficiency of 45%], measured near 40 dBm of output power, and over 28% bandwidth. Using digital predistortion (DPD) linearization, an adjacentchannel leakage ratio (ACLR) of 243 dBc was obtained for a single-carrier W-CDMA signal, at 40.9 dBm and 46% of average output power and drain efficiency, respectively. The designed amplifier represents the first wideband Doherty amplifier reported over extended power back-off range.