Hybrid energy harvesting from ambient electromagnetic (EM), thermal, kinetic, photovoltaic (PV) and wind is a promising green energy solution for powering IoT devices to achieve battery-less operation. However, existing harvesters face limitations in efficiency, input power range and bandwidth. This paper proposes for the first time a cooperative voltage doubler rectifying topology using hybrid EM-PV energy harvesting to address these challenges. Theoretical analysis indicates that the proposed topology can realize high power conversion efficiencies (PCEs) and considerable efficiency gains (EGs) under hybrid input power excitation and with an extended power range. In addition, a post-matching technique for the proposed topology to extend operating bandwidth is presented for the first time. For validation, single-and wide-band cooperative rectifiers are fabricated and measured. In a room with a light intensity of 232 lux, the single-band cooperative rectifier maintains PCEs higher than 46% at 2.4 GHz with the input power range of 25 dB, while the wide-band one realizes PCEs of over 30% with an ultra-wide bandwidth of 0.8 to 2.4 GHz covering GSM, WCDMA, LTE and WLAN. Compared to existing state-of-the-art works, the implemented cooperative rectifiers achieve the largest input power range and widest bandwidth for hybrid ambient energy harvesting.

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).

A tradeoff between bandwidth and back-off range is commonly found in the Doherty power amplifier (DPA). This paper proposes an input phase control mechanism together with a cooperative asymmetric out-phased current load modulation technique. The cooperative asymmetric out-phased current load modulation can extend the output back-off range (OBO). The input phase control mechanism together with modified impedance transforming load modulation networks (LMNs) is used to widen the DPA bandwidth. An input coupled-line coupler is implemented to realize this phase requirement. For demonstration purposes, a DPA with an operating frequency from 1.7 GHz to 2.9 GHz and with a 9-dB OBO range is designed and fabricated using GaN HEMT devices. Continuous-wave measurements show that the implemented DPA exhibits a drain efficiency ranging from 54.5% to 75.6% at saturation and from 41% to 50.6% at 9-dB OBO across the operating bandwidth. When excited by a 20-MHz long-term evolution (LTE) signal with a 9-dB peak-to-average power ratio (PAPR), the implemented DPA achieves average drain efficiencies of 41%-53.8% with an adjacent channel leakage ratio (ACLR) better than -48.1 dBc after digital predistortion (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$0.5\lambda _{g} \times 0.43\lambda _{g}$.

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.

Different from the classic differential evolution (DE) and many of its variants, collective information powered DE (CIPDE) is characterized by the utilization of collective information of population in the mutation and crossover processes of DE. This paper proposes a restart mechanism for CIPDE, to improve its robustness for solving the 100-digit challenge on single objective numerical optimization. Restart based CIPDE (rCIPDE) restarts the population when the unsuccessful update of the population exceeds a threshold value. Simulations on the challenge show that the restart mechanism enhances the performance on five out of the total 10 benchmark functions. According to the competition rule, rCIPDE achieves a total score of 85 (10 marks on each of F1-F7 and F10, 2 marks on F8 and 3 marks on F9).

This paper provides an overview of optimization algorithms for antennas and radio frequency (RF)/microwave circuit designs. The significance of wireless communication to our daily lives and industrial engineering will first be discussed. Antennas and circuits used in wireless communication will then be introduced followed by a discussion on the need for optimization. After that, this paper will focus on three widely used optimization algorithms for antennas and RF/microwave circuit design. A survey of the optimization of antennas and microwave devices available in the literature will be presented and will include the use of other optimization algorithms. For illustration purposes two optimization examples with measurement results will be given.

The design of oscillators using linear 2-port networks are well documented and are usually based on circuits using one active device. Recently there has been renewed interest in the cascode circuit because of its injection locking properties. This gives it tremendous possibilities, in providing very stable high frequency oscillators by locking it to a more stable lower frequency source. The design of oscillators using the cascode circuit has never been completely approached analytically before so the purpose of this paper is to present a method that will enable the analytic approach to oscillator design using the cascode circuit. This method is verified with a design of a low cost, low phase noise power oscillator at 850 MHz.>

An analytic approach to the design of high efficiency tuned power oscillator is presented. By employing large-signal S-parameters, theoretical conditions for optimum operation of the oscillator have been formulated and discussed. Loss due to non-zero switching time, saturation resistance etc. of the transistor employed is accounted for. Various oscillators at 900 MHz were designed using the derived theory. Experimental results showed that the measured data are in good agreement with the predicted data.>