The present paper proposes an optimization design method for the Doherty output matching network (OMN) using impedance–phase hybrid objective function constraints, which possesses the capability of enhancing the efficiency consistency of the Doherty power amplifier (DPA) using integrated enhancing reactance (IER) during the back-off power (BOP) range. By calculating the desired reactance for an extended BOP range and combining it with the two-impedance matching method, the S -parameters of the OMN are obtained. Meanwhile, the impedance and phase constraints of the OMN are proposed to narrow the distribution range of the IER. Furthermore, a fragmenttype structure is employed in the OMN optimization so as to enhance the flexibility of the circuit optimization design. To validate the proposed method, a 1.7–2.5 GHz symmetric DPA with a large BOP range was designed and fabricated. Measurement results demonstrate that across the entire operating frequency band, the saturated output power is >44 dBm, and the efficiency ranges from 45% to 55% at a 9-dB BOP.

This article proposes a design and optimization method for Ultra-Wideband power amplifiers (PAs) using improved multiobjective evolutionary algorithm based on decomposition (MOEA/D) and mixed optimization objective function (MOOF). In order to address the insufficient optimization capabilities of conventional MOEA/D algorithm when dealing with complex Pareto fronts, the optimization algorithm is improved by using adaptive weights, neighborhoods, and global replacement. Initially, based on the sparsity of the population and an external population, the weight vectors corresponding to invalid or crowded individuals in the population are replaced. And, the neighborhoods are adaptively adjusted based on the number of iterations and the sparsity of each individual. Then, a global replacement is employed to accelerate the convergence process. Moreover, a MOOF using the load impedance, output power, efficiency and gain is conducted in the PA optimization design. To reduce the difficulty of impedance judgment, a construction method of impedance solution set based on Poisson disk sampling has been proposed and employed for optimization. For validation, an Ultra-Wideband PA operating at 100–4000 MHz (190.2% fractional bandwidth) was designed and optimized. Measured results show a drain efficiency ranging from 56.0% to 70.9% with an output power higher than 39 dBm at saturation within the whole operational frequency band.

A novel design approach is presented to extend the bandwidth and output power back-off (OBO) range of symmetric Doherty power amplifier. The traditional single variable regulation techniques are effective for output power back-off range extension only at single frequency points. Firstly, one phase dispersion (PD factor) is introduced to characterize the OBO range versus frequency. Secondly, multi-parameters optimization of PD factor, complex combining load (CCL), and out-phased current combining (OCC) is used to alleviate the conflict of bandwidth and OBO range. Dynamically optimizing frequencydependent CCL and OCC parameters to counteract the dispersion effect of the matching network thus enable the wideband OBO extension and expanding design flexibility of symmetric DPA. For demonstration, a symmetric DPA with 9dB OBO range is proposed with a fractional operation bandwidth of 36% within 1.8-2.6 GHz. Under the continuous-wave excitation, the fabricated DPA features a 9-dB output back-off (OBO) efficiency of 37.9%– 55% and a saturated efficiency of 55.7%–66.9%, respectively. When driven by a 20-MHz long-term evolution (LTE) modulated signal with 9-dB peak-to-average ratio (PAPR), the adjacent channel power ratio (ACPR) of the fabricated DPA is better than -50.1 dBc after digital predistortion.

5G and future 6G wireless communication systems are pushing the practical limits on the modulation schemes that can be achieved in practice. These higher-level modulation schemes have further exacerbated the challenges in power amplifier (PA) design. One solution to linearly and efficiently amplify these modulation schemes that have high peak-to-average power ratios (PAPRs), is to use dual-input Outphasing PAs (OPAs). However, the output back-off (OBO) range of a conventional OPA is limited. To mitigate this issue, a new OPA based on an asymmetric architecture is proposed. This new asymmetric OPA is shown theoretically that the OBO range can be extended. To validate the proposal, an OPA is designed using two asymmetric sub-PAs and a modified Chireix combiner. The implemented OPA achieves drain efficiencies of 60.6% and 60% at saturation (44.1dBm) and at 8-dB OBO under CW excitation at 2.58 GHz, respectively. Measurement of the OPA using 20-MHz 5G NR signal with 8-dB PAPR yields an average drain efficiency of 58.3% with an adjacent channel power ratio (ACPR) below −45.1 dBc with digital pre-distortion (DPD).

In this paper, a dual-band Doherty power amplifier (DPA) is proposed that can operate over two wide passbands, which is realized by multiple transmission zeros (TZs) in an all-pass response. The short/open stub loaded stepped-impedance transformers act as the output matching networks (OMNs) in both carrier and peaking paths. The shunted stubs not only generate TZs but also perform impedance conversion, simultaneously satisfying the load-pull requirements at both output back off (OBO) and saturation. This is achieved over two wide frequency ranges. The combination between the OMNs in the two paths realizes a dual-passband response, even though the number of TZs at saturation is one less than that at OBO. A prototype DPA is implemented based on two 10-W GaN transistors to validate the methodology. Measured lower and upper frequency bands are from 1.35 to 1.75 GHz and 3.05 to 3.45 GHz, respectively, with both having 400 MHz operating bandwidths. Measured results demonstrate a maximum saturated gain of 9.2 dB and an output power of 43.8 dBm. Maximum 6-dB OBO and saturated efficiencies ($\eta$) are 58% and 72%, respectively. The circuit occupies a very compact size with an area of$0.5\lambda _{g} \times 0.43\lambda _{g}$.

A design strategy to enhance the efficiency of the dual-mode Doherty power amplifier (DPA) is proposed. The continuous multiple harmonic regulation approach is adopted to realize high efficiency of dual-mode DPA in a wide operating frequency band. Multi-harmonic control and dual-mode impedance matching are performed by a single load modulation network. The DPA’s operating frequency band and harmonic control type can be simultaneously switched through reciprocal gate bias. A DPA using GaN devices with continuousClass$F$for Mode I (1.5–2.4 GHz) andClass$J$/continuous inverseClass$F$for Mode II (1.3–1.4 GHz/2.5–2.7 GHz) is designed and implemented. The fabricated DPA achieves a measured 10.5–14.3-dB gain and 39.2–41.8-dBm saturated power. Due to the proposed strategies, 39.1%–58.2% and 55.6%-71.9% drain efficiencies are obtained respectively at 6-dB output power back-off and saturation output power for the designed DPA. For the down-link long-term evolution (LTE) signal with a channel bandwidth of 20 MHz and a peak-to-average power ratio (PAPR) of 7.5 dB, the average adjacent channel power ratio of the fabricated DPA is better than 40 dBc after digital predistortion at 1.3, 2.0 and 2.6 GHz with average output power back-off (OBO) efficiency of 37.8%, 39.3% and 43.3%.

In this paper, two types of balanced-to-unbalanced quadrature couplers with six hybrid ports and arbitrary power division ratio are proposed. For Type 1, the quadrature coupler can realize two power division functions, including balanced/unbalanced to balanced-unbalanced-hybrid, and for Type 2, the quadrature coupler contains balanced -to-unbalanced and unbalanced-to-balanced power division functions. To reduce the circuit size, double-sided parallel-strip line (DSPSL) swap structure is used to replace the half-wavelength transmission line, and compact circuit size can be easily achieved. To validate the performance of the quadrature couplers, two types of the balanced-to-unbalanced quadrature couplers centered at 1 GHz with power division ratios 1:1 and 3:1 are fabricated and measured, respectively. The common mode suppression higher than 10 dB (bandwidths over than 176%) can be realized, the isolation and in-band matching level can be also improved.

In this paper, a Doherty power amplifier (DPA) using a novel three-port harmonic injection network (HIN) to extend its high-efficiency range is proposed. With the help of a part of the three-port HIN, which is placed between the carrier and peaking branches, the optimal drain fundamental frequency termination for the carrier device at back-off and saturation can be realized simultaneously thus enhancing the efficiency at back-off significantly. Meanwhile, this three-port HIN can also realize second harmonic drain terminations for the carrier and peaking device with the quasi-open and quasi-short circuit at the current plane, respectively. Consequently, the saturated power ratio between peaking and carrier devices is increased, which further extends the back-off range of the asymmetric drain-biased DPA. For demonstration purposes, an extended high efficiency range DPA was designed and fabricated using commercially available GaN HEMT (Cree CGH 40010F) devices. Measured results for this novel idea gave drain efficiencies better than 62.5% at 9-9.5 dB back-off point from 1.60 to 1.95 GHz.