This paper presents a new extended high-efficiency range Doherty Amplifier. This Amplifier uses a main and only a single auxiliary Amplifier. In order to increase efficiency and extend the output high-efficiency range, asymmetrical cells are employed as the main and auxiliary Amplifiers in Class-F harmonic termination complex combining load (CCL) methodology. To verify the proposed methodology, a Doherty Power Amplifier (DPA) with 12 dB output back-off (OBO) is designed and fabricated for wideband code division multiple access (WCDMA) applications. Large signal continuous wave measurement results show the power gain of about 10. 9 dB with a drain efficiency of 66 % at 12 dB of OBO. A two-tone test exhibits a third-order intermodulation distortion (IMD) of lower than-21. 5 dBc. Modulated wave measurements show over 56. 5 % of average drain efficiency and an adjacent channel leakage power ratio (ACLR) of lower than-26. 5 dBc at an output power level of 31. 5 dBm.

Background and Objectives: In this paper, a new design strategy was proposed in order to enhance bandwidth and efficiency of power Amplifier. Methods: To realize the introduced design strategy, a power Amplifier was designed using TSMC CMOS 0. 18um technology for operating in the Ka band, i. e. the frequency range of 26. 5-40GHz. To design the power Amplifier, first a power divider (PD) with a very wide bandwidth, i. e. 1-40GHz, was designed to cover the whole Ka band. The designed Doherty power Amplifier consisted of two different amplification paths called main and auxiliary. To amplify the signal in each of the two pathways, a cascade distributed power Amplifier was used. The main reason for combining the distributed structure and cascade structure was to increase the gain and linearity of the power Amplifier. Results: Measurements results for designed power divider are in good agreement with simulations results. The simulation results for the introduced structure of power Amplifier indicated that the gain of proposed power Amplifier at the frequency of 26-35GHz was more than 30dB. The diagram of return loss at the input and output of power Amplifier in the whole Ka band was less than-8dB. The maximum Power Added Efficiency (PAE) of the designed power Amplifier was 80%. The output P1dB of the introduced structure was 36dB, and the output power of power Amplifier was 36dBm. Finally, the IP3 value of power Amplifier was about 17dB. Conclusion: The strategy presented in this paper is based on usage of Doherty and distributed structures and a new wideband power divider to benefit from their advantages simultaneously.

A continuous-wave solid-state-based power Amplifier is designed and simulated in this paper to work as an RF injector into an ECR ion source chamber. Employing a solid-state radio frequency power Amplifier, instead of microwave tubes, leads to having higher efficiency, lower price, compact size, and longer lifetime. Also, a modular design can be achieved for designing higher output power by repeating lower power sources and combining them. The proposed solid-state source can deliver more than 200 W power to the ion chamber with a single high-power transistor. The selected Doherty high-power transistor is internally matched to 50 ohms and does not need a bias sequence circuit. Two gain stages are applied to drive the high-power transistor. The designed RF source is simulated using the Advanced Design System (ADS) based on the measured scattering parameters of components. Simulations show an output power of more than 57 dBm with a tunable frequency bandwidth from 2. 3 to 2. 5 GHz.

This paper presents a Transimpedance Amplifier (TIA) for high sensitivity Near Infrared Spectroscopy (NIRS). The proposed TIA is based on the Regulated Cascode (RGC) structure with an extra transistor employed to implement additional feed-forward path and achieve higher gain values. The extra transistor senses a partially amplified input signal, available in the conventional circuit, and conveys an additional ac current into the load, which provides a higher gain. In addition, a bandwidth extension method is introduced using a capacitor and resistor, which can improve Amplifier’s bandwidth by 40%. The proposed TIA is designed in 0.18µm CMOS technology and achieves a transimpedance gain of 101.9dB with a -3dB bandwidth of 91.2 MHz considering 2pF of photodiode capacitance at the TIA input. The input referred noise is 4.4pA/√Hz while dissipating 151µW power.

This article describes the first stage in designing and realizing three 100W C-band power Amplifier alternatives based on the GaAs-technology for use in TT&C-transmitters. The operational frequency range spanned from 4. 3GHz to 4. 5GHz. A Gysel power divider was used to feed each branch in the second stage. The Amplifiers were capable of delivering 100W output power. This distributed design of the microwave SSPA results in built in redundancy and graceful degradation of output power should any individual PA section fail. Each branch includes a current sense alarm indication which is monitored and fed to the RF SSPA controller. The amplified outputs of all the symmetric branches are summed up in a passive combing network which routes the resultant high power to the output of the RF SSPA.

Thermal effects induced in Nd: Glass laser disks after optical pumping, have been studied by means of an optical interferometer. For this mean, two configurations with seven and one laser disks at Brewster angle pumped with four flash lamps and a total charging energy 3.1 kJ and 1.8 kJ, respectively. The investigation of interferometer fringes indicated that three regions exist in time domain: vibration and radiation absorption until the ending of optical pumping, vibration and heat conduction until ceasing of  mechanical vibration generated from  the flash lamps shock waves, and finally, disks heating and cooling by convection and conduction mechanisms. The regions terminate 1 ms, 10 ms and at least 1 minute after initiation of the flash lamps discharge current. The first region, depends on the flash lamps discharge circuit, and for the two other regions, vibration and heating are the main mechanisms which depend on thermal properties of the glass disks, installation techniques and cooling.

Different factors such as nonlinear phenomena and mode instability affect the output of the high-power fiber lasers and Amplifiers. Since these devices have many applications in the industry, medicine, and military facilities, the study of the various factors’ effects on their output is directly reflected on the design of high-power lasers and Amplifiers. In the present paper, the mode instability which is the major limiting factor on the output of high power lasers and Amplifiers has been studied, simulated, and investigated. In these high-power devices, the temperature increases due to quantum defects, background loss, and light scattering, which change the refractive index of the fiber material. Variation of the refractive index is the main reason of mode instability in high power fiber lasers and Amplifiers. Mode instability causes the coupling of the fundamental mode to the upper-mode and thus decreases the fundamental mode’ s energy. In this paper, different factors that affect the threshold of the mode instability and power transfer from the fundamental mode to the upper mode have been investigated.

To have both high efficiency and linearity in power Amplifiers linearization techniques should be used. One structure with the ability of cancelling the inherent limitations of the LINC linearization techniques is proposed in this article. The gain and phase imbalances in LINC technique has been compensated using optimization algorithms. According to the analysis a feedback path has been added in the conventional LINC transmitter that calibrates any phase and gain mismatches adaptively; using optimization algorithms. Many simulations have been performed to validate the structure functionality and extracted relations. In this paper M68749 power Amplifier is used at 390MHz frequency with output power of 5 watt. Simulations show that power spectral density of proposed architecture has 40dB/Hz improvement in spreading to adjacent channels.

A novel technique for a self-equalized distributed Amplifier is presented by showing the analogy between transversal filters and distributed Amplifier topologies. The appropriate delay and gain coefficients of Amplifier circuit are obtained by a Fourier expansion of the raised cosine spectrum in the frequency range of 0-40GHz.

A new output structure for class E power Amplifier (PA) is proposed in this paper. A series LC resonator circuit, tuned near the second harmonic of the operating frequency is added to the output circuit. This resonator causes low impedance at the second harmonic. The output circuit is designed to shape the switch voltage of the class E Amplifier and lower the voltage stress of the transistor. The maximum switch voltage of the conventional class E PA is 3.56Vdc. However, higher switch voltage of about 4.5VDC may be occurred, by considering nonlinear drain-to-source capacitance in class E PA. The obtained peak switch voltage of the designed class E PA is approximately 75% of the conventional one with the same conditions, which shows a significant reduction in peak switch voltage. MOSFET parasitic nonlinear gate-to-drain and nonlinear drain-to-source capacitances of the MOSFET body junction diode also affect the switch voltage in class E PA, which are considered in this paper. The actual MOSFETs have these parasitic capacitances; therefore, it is necessary to consider these elements in the design procedure. Reduced switch voltage in class E PA relaxes the breakdown voltage constraints of the active device. In the switch voltage of the designed circuit, the zero voltage and zero derivative switching (ZVS and ZVDS) conditions are satisfied. Simulation of the presented circuit is performed using PSpice and LTspice softwares. For verification of the designed circuit, the presented PA is fabricated and measured.